Academic literature on the topic 'Dental Impression Technique'

Introduction: Taking an impression of the oral cavity, which accurately recreates the prosthetic field, the surrounding hard dental and soft tissues, is one of the main and most important stages in the process of making any fixed prosthetic restoration. In modern prosthetic dentistry, impressions taken with the help of polyether and vinyl polysiloxane impression materials are common. Digital impressions eliminate some of the steps of conventional impression techniques and save clinical time. Aim: The aim of this article is to compare the clinical time in digital and conventional impression techniques from a whole dental arch using a controlled clinical trial. Material and methods: The present study includes 36 patients from Varna who need prosthetic treatment with fixed 3-unit bridge construction. For all participants, the conventional impression technique was performed first and one week later - the digital one. All clinical manipulations related to the implementation of the two impression techniques were performed according to the instructions of the manufacturing companies by the same specialist dentist. Results: In all participants, the time required to perform the digital impression technique is significantly less than that of the conventional impression technique. Conclusion: The digital impression technique has proven to be more efficient in terms of clinical time required for its implementation than the conventional impression technique.

Objective: The objective of the present study was to compare patients’ acceptability, comfort and stress with conventional and digital impressions. Materials and Methods: Thirty young orthodontic patients (15 males and 15 females) who had no previous experience of impressions were enrolled in this study. Conventional impressions for orthodontic study models of the dental arches were taken using an alginate impression material (Hydrogum®, Zhermack Spa, Badia Polesine, Rovigo, Italy). Fifteen days later, digital impressions of both arches were acquired using an intraoral scanner (CS3600®, Carestream Dental, Rochester, NY, USA). Immediately after impression taking, patients’ acceptability, comfort and stress were measured using two questionnaires and the State anxiety scale. Results: Data showed no difference in terms of anxiety and stress; however, patients preferred the use of digital impressions systems instead of conventional impression techniques. Alginate impressions resulted as fast as digital impressions. Conclusions: Digital impressions resulted the most accepted and comfortable impression technique in young orthodontic patients, when compared to conventional techniques.

Purpose/Objectives. Dental students are being introduced to intraoral digital scanning during their undergraduate dental education. Usually, the conventional impression technique is introduced before the digital scanning technique. This study compares the procedure duration, students’ preference, and perceived procedure difficulty level after students’ initial preclinical exposure to either digital scanning using CEREC Omnicam intraoral scanners or conventional impressions using vinyl polysiloxane impression material. Methods. Ninety-six dental students each prepared tooth #36 for an all-ceramic crown on typodont models and were then randomly assigned into either group A: performed digital scan first, or Group B: performed conventional impression first. Procedure time was recorded for both. Immediately following each procedure, students indicated their perceived procedure difficulty. After exposure to both techniques, they selected their preferred one. Results. There was a statistically significant difference between the mean procedure time of both techniques ( P < 0.0001 ), where students spent 663.76 ± 442.50 seconds to complete the conventional impression and 293.32 ± 181.49 seconds to complete the digital scan. Females were significantly faster in completing the conventional impression compared to males. On the contrary, male students were faster in digital scanning than female students. There were no carryover effects in the duration and the initially performed procedure. 76% (73 of 96) of participants preferred digital scanning with no statistical significance shown between the preferred and initially performed procedure. Participants perceived conventional impressions to be more difficult than digital scans. There was a weak positive correlation between the VAS score and the procedure time for the digital technique (R = 0.25) and a moderate positive correlation for the conventional technique (R = 0.45). Conclusions. The digital technique was preferred and perceived as easier than the conventional among undergraduate dental students with no impression-making experience, suggesting their readiness for new technology uptake. However, no significant correlation was found between the initially performed procedure and preference.

Dental implant is defined as a prosthetic device made of alloplastic material(s) implanted into the oral tissues beneath the mucosal and/or periosteal layer and on or within the bone to provide retention and support for a fixed or removable dental prosthesis; a substance that is placed into and/or on the jaw bone to support a fixed or removable dental prosthesis [Glossary of Prosthodontic Terms (GPT 9)]. Dental implants have been swiftly gaining popularity as a treatment modality of choice in prosthodontics i.e. both fixed and removable. Impression is defined as negative likeness or copy in reverse of the surface of an object; an imprint of the teeth and adjacent structures for use in dentistry (GPT 9). Impressions in implantology is a crucial step and involves a meticulous workflow in achieving the passive fit for the long-term success of the final implant prosthesis. This involves accurately relating and recording the exact replica of the implant analogue or the implant abutment to the other structures in the oral cavity. A plethora of factors determine the accuracy of the implant impressions namely the choice of impression tray, impression material, number of implants, depth, position and angulation of implants and most importantly the technique encountered for recording the impression. This short communication briefly portrays the armamentarium and components used along with the selection of a suitable impression tray, impression material and impression technique devised for the precise impression of the implant for the ultimate success of the final prosthesis.

Major advances in impression materials and their application have occurred during the last decade, with greater emphasis being placed on rubber impression materials than on dental compound, zinc oxide-eugenol, and agar and alginate. Of particular interest has been the effect of disinfection solutions on the qualities of impressions and the biocompatibility of impression materials. The principal advance in hydrocolloids has been the introduction of the agar/alginate impression technique, which has simplified the procedure and improved the quality of gypsum dies compared with those prepared in alginate impressions. The tear strength of some alginates has been improved, and some have been formulated so that the powder is dustless, thus reducing the health hazard as a result of patient inhalation of dust during the dispensing process. Polyether and silicone impression materials have been modified so that the working time, viscosity, and flexibility of the polyethers have been improved and, with the introduction of addition silicones, their accuracy has become exceptional. Although the early addition silicones liberated hydrogen after setting, thus delaying the pouring of models and dies, most addition silicones have been improved so that no hydrogen is released and dies can be poured immediately. The introduction of automatic mixing systems for addition silicones has simplified their manipulation, has reduced the number of voids in impressions, and has reduced the amount of material wasted. The incorporation of surfactants into addition silicones has made them hydrophilic, with wetting properties similar to those of polyethers, and has made pouring bubble-free gypsum dies easier. This review is confined to published and unpublished information of the past decade. It will also suggest trends that should be anticipated in the near future based on this information. The review will not present information developed before 1975, which is available in several textbooks on dental materials by Craig (1985a), Phillips (1982), and Williams and Cunningham (1979).

Introduction: Dimensional accuracy of cast obtained after making impressions is crucial factor for the quality of fixed prosthodontic treatment. The impression technique with different thickness of putty wash material is critical factor affecting this accuracy. There is much discussion in the dental literature concerning the effect of this impression technique on the accuracy of cast restorations. Materials and methods: This in-vitro study was carried out in 60 impression made from master model with Polyvinyl siloxane impressions material using single step putty- wash technique and two step putty-wash technique with varying spacer thickness (0.5mm, 1mm, 1.5 mm). It was further divided into four groups. Group I: Single step putty-wash impression technique, Group II: Two step putty-wash impression technique with 0.5mm spacer, Group III: Two step putty-wash impression technique with 1mm spacer, Group IV: Two step putty-wash impression technique with 1.5mm spacer. Each group consists of 15 impressions. Casts were poured using type IV dental stone after 1 hour. After 24 hour the die of each cast was scanned using CAD/CAM digital scanner and measured mesiodistally, facio-lingually, height (cervico-occlusally), interabutment or interdie distances. The data were recorded and statically analyzed. Results: The highest mean values of mesio-distal, bucco-lingual, cervico-occlusal distances were shown by Group I, whereas the inter-die distance showed equal mean value in Group I, II and III. With the increase in the spacer thickness, the mean value also increases in mesio-distal distance. The mean measurement of bucco-lingual dimension was highest when spacer thickness was 0.5mm and it declined with the increase in spacer thickness. The spacer thickness had no effect on cervico-occlusal and inter-die dimensions. Conclusions: Within the limitations of the study, accuracy of cast obtained from single step putty-wash technique was more accurate than two step putty-wash technique. In two step putty-wash technique, 1.5 mm thickness of spacer showed more accurate cast in comparison to 0.5mm and 1mm.

Objective: Dental casts are an important aspect in the treatment planning, documentation, and analysis of the dental arch forms of infants with cleft lip and palate (CLP). Impression taking in a neonate is a technique-sensitive procedure, which can result in foreign body dislodgement and carries a small risk of aspiration and airway obstruction. The advent of digital dental technologies and intraoral scanning may facilitate safer, more effective, and accurate impressions for CLP infants. Design: A digital intraoral scan of a 3-month-old with bilateral CLP (BCLP) was compared with a conventional alginate impression taken prior to primary lip repair. Setting: Princess Margaret Hospital for Children. Main Outcome Measures: To test the applicability and accuracy of digital impression taking for a neonate with BCLP and palate using digital morphometrics. Results: The average deviation of points ranged above and below the plane of superimposition from +0.78 mm to −0.42 mm with a maximum range of +2.80 mm to −2.80 mm and standard deviation of 0.88 mm. The premaxillary segment showed the greatest degree of variation. Conclusions: This is to our knowledge the first report that illustrates the use of a digital impression system to scan the oral structures of a neonate with BCLP. Digital scanning was found to be fast, accurate, and safe, when compared to a conventional alginate impression technique.

Abstract A quality-made dental impression is a prerequisite for successful fixed-prosthodontic fabrication and is directly dependent on the dimensional stability, accuracy and flexibility of the elastomeric impression materials, as well as on the appropriately used impression techniques. The purpose of this paper is to provide a literature review of relevant scientific papers which discuss the use of various silicone impression materials, different impression techniques and to evaluate their impact on the dimensional stability and accuracy of the obtained impressions. Scientific papers and studies were selected according to the materials used, the sample size, impression technique, storage time, type of measurements and use of spacer for the period between 2002 and 2016. In the reviewed literature several factors that influence the dimensional stability and accuracy of silicone impression molds, including the choice of the type of viscosity, impression material thickness, impression technique, retention of the impression material on the tray, storage time before the casting, number of castings, hydrophilicity of the material, release of byproducts, contraction after polymerization, thermal contraction and incomplete elastic recovery were presented. The literature review confirmed the lack of standardization of methodologies applied in the research and their great diversity. All findings point to the superiority of the addition silicone compared to the condensation silicone.

Background/Aim: The purpose of this study was to evaluate the quality of impressions made with vinyl polysiloxane (VPS) material in clinical conditions by using the one-step impression technique, and the quality of casts generated from these impressions. The effect of operator, number and location of abutments, and presence of bleeding were also investigated. Material and Methods: A total of 150 fixed dental prosthesis (FDP) impressions were taken and considered acceptable by 3 experienced prosthodontists in a clinic in an institutional setting. The impressions were evaluated and rated by another experienced prosthodontist and respective casts were evaluated and rated by an experienced dental technician using a digital microscope with ×200 magnification. The defects observed were noted as bubbles, voids, tears, or other defects. A scale was structured for the impressions and casts with ratings of Alpha (excellent; no defects), Bravo (acceptable; small defects), Charlie (inadequate; defects that require remaking of impression), and Delta (unacceptable; substantial defects at preparation finish lines). The data were analyzed with the Chi-square test for inter-operator, number of abutments, and location of prepared tooth variables (a=0.05). Results: The scale ratings were 85 Alpha (57%), 52 Bravo (34%), 6 Charlie (4%), and 7 Delta (5%) for the impressions, and 81 Alpha (54%), 58 Bravo (39%), 4 Charlie (3%), and 7 Delta (5%) for the respective casts. Sixty-nine percent of the impressions and respective casts were rated with the same score. The scale rating results were not influenced by inter-operator variability or number of abutments. Location of the prepared tooth was significant for anterior/posterior (p=0.04), but was not significant for maxilla/ mandible (p>0.05). Bleeding at the preparation site had a significant effect on the acceptability of the impression (p=0.003). Conclusions: The acceptability of VPS impressions using onestep technique was independent of the operator, number of abutments, or whether the prepared tooth was in maxilla or mandible. Impressions of teeth in the anterior region were more acceptable than those located in the posterior. Bleeding negatively affected the acceptability of the impressions. Clinicians may use VPS impressions for the fabrication of FDPs using onestep dual-phase technique. However, clinicians should carefully evaluate their impressions when bleeding is present when using this technique.

Background: Replacement of missing tooth plays an important role in patient’s comfort and self-esteem. Aims and Objectives: The aims of this study were to investigate the most commonly used impression materials and techniques practiced for crowns and bridgework by prosthodontists and general dental practitioners compared to the theoretical methods suggested in the literature and to determine the clinical factors that might influence the decision-making process for the selection of impression materials and techniques. Materials and Methods: Pre-tested and pre-validated structured and closed-ended anonymous questionnaire was shared with general dental practitioners and prosthodontists. Results: Most of the prosthodontists use diagnostic impression compared to general dental practitioners (P<0.01). Full-arch tray was used by general dental practitioners significantly more frequently compared to prosthodontists (P<0.01) for single anterior, single posterior, anterior, and posterior bridge preparations. Alginate hydrocolloid was used by general dental practitioners significantly more than prosthodontists (P<0.05); however, addition silicone and condensation silicone were used by prosthodontists significantly more than general dental practitioners (P<0.05). For the impression technique followed in case of using elastomeric impression materials, the prosthodontists used the two-step putty reline technique with spacer more commonly, while general dental practitioners used the multiple mix technique (P<0.01). For the use of provisional restoration for single tooth crowns and for all the bridges, prosthodontists used provisional restoration in significantly higher proportion as compared to general dental practitioners (P<0.01). Conclusion: According to our study compared to general dental practitioners, practices of the prosthodontists regarding use of fixed partial denture is more in line with the current global trend.

Thesis (M.S.)--West Virginia University, 2003.
Title from document title page. Document formatted into pages; contains viii, 43 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 41-42).

Orientador: Francisco de Assis Mollo Junior
Banca: Sergio Sualdini Nogueira
Banca: Mauro Antônio de Arruda Nóbilo
Resumo: Dentre as inúmeras fases clínicas e laboratoriais de um tratamento protético, as técnicas de moldagem para próteses implantossuportadas são ainda responsáveis por grande preocupação e controvérsia entre os pesquisadores. Este estudo in vitro teve como objetivo avaliar a precisão de uma técnica de registro (Index) e de três técnicas de moldagem (transferentes Quadrados, Quadrados unidos e Quadrados com prolongamentos em forma de hélice) associadas a duas situações clinicas (análogos alinhados e não-alinhados). Todos os componentes protéticos utilizados foram da empresa Conexão (Conexão Sistemas de Prótese). Foi construído um modelo mestre de resina epóxica simulando um arco inferior parcialmente desdentado onde foram fixados seis análogos de pilares Micro-Unit. Duas estruturas metálicas de três elementos sendo três alinhados e três não-alinhados e vinte e uma moldeiras individuais de resina acrílica foram confeccionadas. O material de moldagem utilizado foi um poliéter (Impregum Soft Média Viscosidade - 3M ESPE) e o gesso empregado foi um gesso tipo IV (FujiRock -GC Corp), espatulado à vácuo. Foi obtido um total de vinte e um modelos, sendo sete por técnica, mais sete registros do index... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The present in vitro study compared the dimensional accuracy of a master cast (control group) with verification jig (Index) and 3 impression techniques (squared impression copings, squared impression copings splinted with autopolymerizing acrylic resin and squared impression copings with prolongations created from autopolymerizing acrylic resin in the vestibule-lingual direction). Materials and Methods. An epoxy resin cast of a partially dentulous mandibular was fabricated with 6 abutment replicas, two passive implant frameworks and twenty-one identical custom impression trays were made with autopolymerizing acrylic resin... (Complete abstract, click electronic access below)
Mestre

Orientador: José Maurício dos Santos Nunes Reis
Resumo: Este estudo analisou a exatidão de modelos totais de gesso, obtidos a partir de diferentes técnicas e materiais de moldagem, tempos e materiais de vazamento, levando em consideração as mensurações de área, volume e angulação nos eixos X, Y e Z de pontos de referência específicos em modelo mestre (baseline), moldes e, por posteriormente, em modelos de gesso de cada condição experimental. Foi utilizado um modelo mestre com preparos nos dentes 14, 16, 21 e 25, com demarcações pontuais em suas superfícies oclusais, que funcionavam como pontos de referência. Realizaram-se três técnicas de moldagem: (T1) mistura simultânea, (T2) reembasamento - alívio com filme de PVC e (T3) moldagem digital (escâner intra-oral) - Cerec Conect Omnicam (Sirona). Para cada técnica de moldagem/tempo de vazamento foram obtidos 8 moldes totais, por único operador calibrado (ICC=0,99), com moldeira metálica de estoque e silicone de condensação (Speedex; Coltène/Whaledent Inc.) ou adição (Express XT; 3M ESPE). Os vazamentos foram realizados com gessos tipo IV convencional (GC Fuji Rock EP - GC America) e de expansão nula (Zero Stone - Dentona AG). Nos moldes com silicone de condensação o gesso foi vazado após 30 minutos, 3 ou 7 dias. Nos moldes em silicone de adição os modelos foram obtidos após 2 horas, 3, 7 ou 15 dias. Para a análise tridimensional, utilizou-se software para gerenciamento de imagens e análise das malhas tridimensionais (Rhinoceros - versão 5.3.2) obtidas com escâner óptico de bancada (R... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This study analyzed the accuracy of total gypsum casts obtained from different casting techniques and materials, casting times and materials, taking into account the measurements of area, volume and angulation in the X, Y and Z axes of reference points specific master model (baseline), in the impression and, later, in the gypsum casts of each experimental condition. A master model was used with teeth 14, 16, 21 and 25, with punctual demarcations on its occlusal surfaces, which functioned as reference points. Three impression techniques were performed: (T1) simultaneous mixing, (T2) relining-relief with PVC film and (T3) chairside digital impression - Cerec Conect Omnicam (Sirona). For each impression technique / casting time, 8 total impression were obtained by single calibrated operator (ICC = 0.99), with metal stock tray and condensation silicone (Speedex; Coltène / Whaledent Inc.) or addition (Express XT 3M ESPE). The gypsum casts pouring process were performed with type IV conventional gypsum (GC Fuji Rock EP - GC America) and zero expansion one (Zero Stone - Dentona AG). For impressions with condensation silicone the cast was poured after 30 minutes, 3 or 7 days. For the addition silicone impressions, the gypsum casts were obtained after 2 hours, 3, 7 or 15 days. For the three-dimensional analysis, a software was used to manage threedimensional images (Rhinoceros - version 5.3.2) allowing the investigation of virtual images (three-dimensional meshes) made with an optical... (Complete abstract click electronic access below)
Doutor

U uvodnom delu doktorske disertacije opisane su osnovne konvencionalne metode otiskivanja, kao i modifikovane tehnike koje se koriste u savremenoj implant protetici. Prikazana je specifičnost biomehanike implantno nošenih i poduprtih nadoknada u odnosu na biomehaniku nadoknada retiniranih prirodnim zubima. Akcenat je stavljen na kompleksnost problematike postizanja apsolutno pasivnog naleganja nadoknade na nosač implanta (abatment), sa posebnim osvrtom na uticaj same procedure otiskivanja implanata i angulacije implanata na tačnost naleganja. Detaljno su opisani i svi ostali faktori koji mogu da utiču na tačnost radnih modela pri izradi nadoknada na implantima, pozivajući se na aktuelne podatke iz literature i naučno opravdanje za potrebe istraživanja. Cilj rada je bio ispitati uticaj metode otiskivanja, angulacije implanata i vrste otisnog materijala na tačnost definitivnog radnog modela za izradu implantno nošenih zubnih nadoknada. Eksperiment je obavljen u in vitro uslovima. Istraživanje je bazirano na ispitivanju tačnosti otiskivanja pomoću tri različite metode otiskivanja (direktne, indirektne i modifikovane „splint“ metode), dve vrste elastičnih otisnih materijala (adicionog silikona i polietra) i uticaja dve različite grupe implanata (anguliranih od 20° i paralelnih implanata) na tačnost otiskivanja. Master (referentni) model je isplaniran tako da simulira čest klinički slučaj parcijalne bezubosti gornje vilice (klasa Kenedi I), koji je osim dva ugrađena angulirana implanta sa jedne, i dva paralelna implanta sa druge strane, podrazumevao i prisustvo brušenih zuba, pripremljenih za prihvatanje keramičkog mosta u frontalnoj regiji. Otiskivanje zuba i implanata vršeno je istovremeno i drugi deo istraživanja je obuhvatao ispitivanje uticaja primenjene metode i materijala na tačnost otisnutih površina zuba. Time je prošireno polje istraživanja i omogućeno donošenje zaključka o pravoj indikaciji metode i materijala za otiskivanje konkretnog kliničkog slučaja. Kompletna metodologija izrade master i definitivnih radnih (replika) modela, kao i sama procedura otiskivanja, izvedena je po najsavremenijim principima istraživanja, uz upotrebu instrumenata i materijala vodećih svetskih proizvođača. Za potrebe analize odstupanja implanata i zuba na replica modelima u odnosu na referentni, modeli su podvrgnuti optičkoj 3D (trodimenzionalnoj) digitalizaciji pomoću dva savremena laboratorijska skenera koje karakteriše izuzetna tačnost skeniranih površina. Prvo je digitalizovan master model za potrebe dobijanja nominalne geometrije, a nakon toga 30 replika modela, za potrebe uporedne geometrijske analize. Analiza je vršena pomoću najnovijeg specijalizovanog softverskog programa, primenom metode CAD-inspekcije (eng. Computer-Aided Design). Geometrijska analiza odstupanja brušenih zuba (patrljaka) izvedena je tehnikom preklapanja odnosno superpozicije (eng. bestfit) realne geometrije (na replika modelu) sa nominalnom geometrijom (na master modelu). Za razliku od analize patrljaka, za potrebe geometrijske analize odstupanja implanata kreiran je lokalni koordinatni sistem za svaki analizirani implant, pomoću specijalnih abatmenta upotrebljenih za digitalizaciju i uvozom 3D modela implanata iz CAD biblioteke proizvođača. Odstupanja su analizirana u odnosu na centar baze implanta (odstupanje od centra) i u odnosu na centralnu osu implanta (ugao odstupanja), što je omogućilo tačno prostorno orijentisanje implanata na replika modelima u poređenju sa referentnim. Ova metodologija je originalna, jer je u odnosu na metodologije koje su do sada korišćene u svrhu prostorne orijentacije implanata, uvođenjem novih parametara u analizu, omogućila tačnije defi nisanje prostornog odstupanja analiziranih implanata. Rezultati dobijeni u istraživanju doveli su do zaključka da metoda otiskivanja i vrsta otisnog materijala utiču na tačnost otiskivanja implanata. Takođe, angulacija implanata od 20° ima veći uticaj na tačnost definitivnih radnih modela u poređenju sa paralelnim angulirana implanta sa jedne, i dva paralelna implanta sa druge strane, podrazumevao i prisustvo brušenih zuba, pripremljenih za prihvatanje keramičkog mosta u frontalnoj regiji. Otiskivanje zuba i implanata vršeno je istovremeno i drugi deo istraživanja je obuhvatao ispitivanje uticaja primenjene metode i materijala na tačnost otisnutih površina zuba. Time je prošireno polje istraživanja i omogućeno donošenje zaključka o pravoj indikaciji metode i materijala za otiskivanje konkretnog kliničkog slučaja. Kompletna metodologija izrade master i definitivnih radnih (replika) modela, kao i sama procedura otiskivanja, izvedena je po najsavremenijim principima istraživanja, uz upotrebu instrumenata i materijala vodećih svetskih proizvođača. Za potrebe analize odstupanja implanata i zuba na replika modelima u odnosu na referentni, modeli su podvrgnuti optičkoj 3D (trodimenzionalnoj) digitalizaciji pomoću dva savremena laboratorijska skenera koje karakteriše izuzetna tačnost skeniranih površina. Prvo je digitalizovan master model za potrebe dobijanja nominalne geometrije, a nakon toga 30 replika modela, za potrebe uporedne geometrijske analize. Analiza je vršena pomoću najnovijeg specijalizovanog softverskog programa, primenom metode CAD-inspekcije (eng. Computer-Aided Design). Geometrijska analiza odstupanja brušenih zuba (patrljaka) izvedena je tehnikom preklapanja odnosno superpozicije (eng. bestfit) realne geometrije (na replika modelu) sa nominalnom geometrijom (na master modelu). Za razliku od analize patrljaka, za potrebe geometrijske analize odstupanja implanata kreiran je lokalni koordinatni sistem za svaki analizirani implant, pomoću specijalnih abatmenta upotrebljenih za digitalizaciju i uvozom 3D modela implanata iz CAD biblioteke proizvođača. Odstupanja su analizirana u odnosu na centar baze implanta (odstupanje od centra) i u odnosu na centralnu osu implanta (ugao odstupanja), što je omogućilo tačno prostorno orijentisanje implanata na replika modelima u poređenju sa referentnim. Ova metodologija je originalna, jer je u odnosu na metodologije koje su do sada korišćene u svrhu prostorne orijentacije implanata, uvođenjem novih parametara u analizu, omogućila tačnije definisanje prostornog odstupanja analiziranih implanata. Rezultati dobijeni u istraživanju doveli su do zaključka da metoda otiskivanja i vrsta otisnog materijala utiču na tačnost otiskivanja implanata. Takođe, angulacija implanata od 20° ima veći uticaj na tačnost definitivnih radnih modela u poređenju sa paralelnim implantima. Time su potvrđene radne hipoteze doktorske disertacije. „Splint“ metoda otiskivanja i adicioni silikon izdvojili su se kao najtačniji pri otiskivanju implanata. Kombinacije „splint“ metode sa adicionim silikonom i polietrom i otvorene metode sa adicionim silikonom dale su bolje rezultate pri otiskivanju anguliranih implanta, dok je u grupi paralelnih implanata zaključeno da metoda i materijal ne utiču na tačnost otiskivanja. „Splint“ i otvorena metoda i adicioni silicon pružili su najtačnije otiske brušenih zuba. „Splint“ metoda u kombinaciji sa adicionim silikonom dala je najmanja ukupna odstupanja pri otiskivanju implanata i zuba zajedno. Prezentovana studija je specifi čna, kako po izboru zadatog kliničkog slučaja I uporednoj analizi tačnosti istovremenog otiskivanja implanata i zuba, tako i po samoj metodologiji analiza odstupanja implanata, te predstavlja originalni doprinos naučnoj i stručnoj javnosti.
The introductory part of the PhD-theses describes fundamental conventional impression methods, as well as modified techniques used in modern-day implant prosthetics. The biomechanics specificity of the implant supported prosthesis in relation to the biomechanics of natural-teeth retained prosthetics is showed. The emphasis is on the issue’s complexity at accomplishing the absolute passive fit of the prosthesis onto the abutment, with particular regard to the impact of the implant impression procedure and implant angulation its elf. A detailed description is provided for all other factors which can influence the accuracy of working casts during implant-based dental prosthesis, making reference to the current data in the literature, as well as to the scientific justification for research. The aim of the study was to examine the influence of the impression method, implant angulation and type of the impression material on the accuracy of the definitive working model for production of the implant-supported dental prosthesis. The experiment was conducted in the in vitro conditions. The research is based on examining the impression accuracy by using three different impression methods (direct, indirect, as well as modifi ed “splint” method), by using two types of elastic impression materials (addition silicone and polyether), as well as the impact from two different implant groups (angled at 20°, and parallel ones). Master (referential) model was planned to simulate a common clinical case of the upper jaw partial edentulism (Kennedy 1st class), which apart from the two angulated implants on one side, and two parallel implants on the other, also presupposed presence of milled teeth, prepared to accept ceramic dental bridge in the frontal region. Impression of teeth and implants was conducted simultaneously, and second part of the research encompassed examination of the applied method’s and material’s impact onto accuracy of the impressed teeth surfaces. This expanded the research fi eld and enabled drawing conclusions regarding the appropriate method indication and material for impression of a particular clinical case. Complete production methodology of master and definitive working casts (replicas), as well as the impression procedure itself, were all conducted according to the cutting-edge research principles, as well as with the application of instruments and materials of leading world producers. For the purpose of the analysis of implants and teeth deviation on replica models in relation to the reference model, the models underwent optical 3D (three-dimenzional) digitalization by using two state-of-the-art laboratory scanners characterized by exceptional accuracy of scanned surfaces. First model to be digitalized was the master one, in order to obtain nominal geometry, following which 30 model replicas were scanned, for the purpose of comparative geometrical analysis. The analysis was conducted by using latest specialized software designed for CAD (Computer-Aided Design) inspection method. Geometric analysis of the milled teeth (tooth abutments) deviation was conducted by using the overlapping superposition technique (bestfit) real geometry (on the replica model) with nominal geometry (on the master model). As opposed to the teeth-stump analysis, for the purpose of geometrical analysis of implant deviations, a local coordinate system for each analyzed implant was created, by using special abutments used for digitalization and by importing 3D implant models from the manufacturer’s CAD library. Deviations were analyzed in relation to the implant base center (deviation from the center), and in relation to the implant central axis (deviation angle), which enabled accurate implant spatial orientation on the replica models in comparison the referential ones. This methodology is original, since unlike methodologies used so far for implant spatial orientation, it has enabled, through introducing new parameters into analysis, a more accurate defining of analyzed implants spatial deviation. Results obtained during research have led to the conclusion that that the impression methodology and type of the impression material influence the implant impression accuracy. Also, implant angulation of 20° has a higher impact on accuracy of definitive working models in comparison with parallel implants. This confirms the PhD-thesis working hypotheses. The “splint” impression method and addition silicone have excelled as most accurate at implant impression. Combination of “splint” methods with addition silicone and polyether and opened methods with addition silicone proved to obtain better results when impressing angulated implants, while in the group of parallel implants, it was concluded that the method and material do not infl uence the impression accuracy. The “splint” and the open method and addition silicone provided most accu rate imprints of ground teeth. The “splint” method in com bination with addition silicone provided the least over all deviation at impression of implants and teeth together. The presented study is a specifi c one, both in terms of selection of the given clinical case and comparative analysis of the simultaneous impression of teeth and implants, but also in terms of the methodology itself used to analyze implant deviation, which in its own right represents an original contribution to the scientific and expert public.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Dentre as inúmeras fases clínicas e laboratoriais de um tratamento protético, as técnicas de moldagem e vazamento para próteses implantossuportadas são ainda responsáveis por grande preocupação e controvérsia entre os pesquisadores. Este estudo in vitro teve como objetivo avaliar a precisão de uma técnica de registro (Index) e de três técnicas de moldagem (transferentes Cônicos, Quadrados e Quadrados unidos) associadas a três técnicas de vazamento (Convencional, com tubos de Látex e com análogos unidos com Duralay) para próteses implantossuportadas. Todos os componentes protéticos utilizados foram da empresa Conexão (Conexão Sistemas de Prótese). Foi construído um modelo mestre de latão simulando um arco inferior desdentado onde foram fixados provisoriamente quatro análogos de pilares Micro-Unit perpendicularmente à superfície e paralelos entre si, sendo denominados análogos A, B, C e D. Uma estrutura metálica foi confeccionada e parafusada a quatro novos análogos. Este conjunto foi cimentado passivamente no modelo mestre com resina epóxica. Foram confeccionadas (com 2 mm de alívio) uma moldeira individual de alumínio para a técnica com os transferentes quadrados unidos e outra para as técnicas com os transferentes cônicos e quadrados. O material de moldagem utilizado foi um poliéter (Impregum Soft Média Viscosidade - 3M ESPE) e o gesso empregado foi um gesso tipo IV (Vel-Mix, Kerr), espatulado à vácuo. Foi obtido um total de cinquenta modelos, sendo cinco por técnica. A estrutura metálica foi parafusada com um torque de 10 Ncm em todos os modelos no análogo A, enquanto as medições das fendas formadas foram feitas nos análogos C e D. Este processo foi repetido no análogo D, anotando-se as medidas dos análogos A e B. Estas medições foram feitas por um programa (Leica QWin) que recebia as imagens de uma câmara de vídeo...
Among the countless clinical and laboratories procedures of a prosthetic treatment, the implant impression and pouring techniques for implant-supported restorations are still responsible for great concern and controversy among the researches. This study in vitro investigated the accuracy of a stone Index and of three impression techniques (tapered impression copings, squared impression copings and squared impression copings splinted with Duralay resin) associated to three pouring techniques (Conventional, with tubes of Latex and joining the analogs with Duralay resin) for an osseointegrated implant-supported prostheses. Conexão (Conexão Systems of Prosthesis) prosthetic components were used. A mandibular brass cast was constructed with four stainless steel implant abutments analogs 90° to the surface and parallel among themselves, being denominated analog A, B, C and D. A master framework was made and screwed to four new analogs, which were cemented passively into the model master with epoxy resin. This formed a metal implant cast with a passive implant framework fitted to it. An aluminum custom tray was fabricated for the technique copings splinted with Duralay and other for the techniques tapered and squared copings. Polyether impression material (Impregum Soft medium consistency - 3M ESPE) was used for all impressions. A total of fifty stone casts were formed by carefully vibrating improved dental stone (Vel-Mix, Kerr), mixed under vacuum, being five for technique. The standard framework was seated on each cast and guide pin was tightened in the analog A to 10 Ncm using a torque driver, while the measurements of abutment / framework interface gaps were made in analogs C and D. This process was repeated in analog D, being written down the measures of the analogs ones A and B. These measurements were analyzed using software (Leica QWin) that received the images of a video ...(Complete abstract, click electronic access below)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Dentre as inúmeras fases clínicas e laboratoriais de um tratamento protético, as técnicas de moldagem para próteses implantossuportadas são ainda responsáveis por grande preocupação e controvérsia entre os pesquisadores. Este estudo in vitro teve como objetivo avaliar a precisão tridimensional das moldagens para próteses sobre implantes, utilizando-se a técnica direta, variando-se os transferentes (transferentes quadrados, transferentes quadrados com extensão vestíbulo-lingual, transferentes quadrados unidos com Duralay, transferentes quadrados unidos com barra de metal e Index), o tipo de material de moldagem (Impregum Soft média viscosidade, Express consistência regular - 3M ESPE) e a disposição dos implantes (alinhados e não-alinhados). Todos os componentes protéticos utilizados foram da empresa Conexão (Conexão Sistemas de Prótese). Foi construído um modelo mestre de resina epóxica simulando um arco inferior parcialmente desdentado onde foram fixados seis análogos de pilares Micro-Unit. Foi obtido um total de cinqüenta e seis modelos, sendo sete por técnica, mais sete registros do index. Estas medições tridimensionais foram feitas por um programa (ReflexSoft 1.0) que recebia as imagens StereoMicroscópio Reflex. Os valores de distorção médios obtidos foram: Index = 25,88μm (±3,41 SD); Quadrado/ Impregum = 80,22μm (±6,36 SD); Quadrado/ Express = 80,72 μm (±4,92 SD); Quadrado Duralay/Impregum = 84,63 μm (±9,22 SD); Quadrado Duralay/ Express =78,73 μm (±6,84 SD); Quadrado hélice/ Impregum = 30,72 μm (±3,53 SD); Quadrado Hélice/ Express = 30,21 μm (±4,08 SD); Quadrado Barra Metálica/Impregum = 57,08 μm (±5,96 SD); Quadrado Barra Metálica/ Express = 50,77 μm (±4,82 SD). Os testes estatísticos utilizados foram Holm-Sidak Method e Mann-Whitney (a=0,05). Pode-se concluir que em relação às técnicas estudadas que:...
An epoxy resin cast of a partially dentulous mandibular was fabricated with 6 abutment replicas. Nine groups were formed: (Index(I); squared impression copings/ Impregum (SI), metal splinted Impression copings/ Impregum (MI), Duralay splinted impression copings/Impregum (DI), Squared modified Impression copings/ Impregum (SMI), squared impression copings/ Express (SE), metal splinted Impression copings/ Express (ME), Duralay splinted impression copings/ Express (DE) and Squared modified Impression copings/ Express (SME) with 7 casts each were formed,. The measurements were analyzed using software that received the images of a video camera coupled Reflex microscope. Data were analyzed with a 1-way analysis of variance at α <.05, followed by the Holm-Sidak Method and Mann-Whitney test (α <.05). Results. The mean values of abutment/framework interface gaps were: I group 25,88μm (±3,41 SD); SI group 80,22μm (±6,36 SD); SE group 80,71μm (±4,92 SD); MI group 57,07μm (±5,96 SD); ME group 50,76μm (±4,82 SD); DI group 84,63μm (±9,22 SD); DE group 78,73μm (±6,84 SD); HI group 30,71μm (±3,53 SD); HE group 30,21μm (±4,08 SD). No significant difference was detected between I group and HI group, and between I group and HE group (P <.05). Did not exist superiority regarding the impression material.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Desde que não há consenso em relação a técnica de moldagem mais precisa, foi objetivo deste estudo in vitro avaliar a precisão de 1 técnica de registro (Index de resina composta) e de 5 técnicas de moldagem para próteses implantossuportadas (transferentes quadrados, quadrados jateados, quadrados com extensão lateral, quadrados unidos com Duralay e quadrados unidos com barra de metal) empregando-se 3 materiais de moldagem: silicone de polimerização por adição consistência densa/fluida com moldeira de estoque de inox, poliéter média viscosidade e silicone de polimerização por adição consistência regular com moldeira individual. Foram construídos 1 modelo mestre com 4 análogos de pilares Micro-Unit e 1 estrutura metálica. Obteve-se do modelo mestre um total de 45 modelos, sendo 5 por técnica. A estrutura metálica foi parafusada utilizando-se a técnica de mensuração de fendas por um parafuso. Estas medições foram feitas com o auxílio do programa Leica QWin que recebeu as imagens de uma câmara de vídeo acoplada a uma lupa com um aumento de 100 x. Os resultados obtidos foram analisados estatisticamente utilizando o teste de Kruskal-Wallis seguido pelo método de Dunn, !=0,05. Dentro das condições experimentais deste estudo, podese concluir que não houve diferença estatística entre: modelo mestre (31,63 !m), quadrado Impregum (38,03 μm), quadrado jateado Impregum (46,80 μm), Index (45,25 μm) e quadrado com extensão lateral Express consistência densa/fluida (51,20 μm), sendo esta a eleita. Devido aos piores resultados obtidos com as técnicas quadrado Express regular (151,21 μm) e quadrado jateado Express regular (136,59 μm), o material de moldagem Express consistência regular não deve ser empregado, sendo escolhido então para ser utilizado com moldeiras individuais o Impregum viscosidade média. Caso o cirurgião-dentista pretenda realizar...
Since there is still no consensus regarding the most accurate impression techniques, it was the purpose of this study compared the dimensional accuracy of stone index and of 5 impression techniques for implant-supported prostheses (squared impression copings, modified squared, !squared sandblasted and coated with impression adhesive, modified squared, Duralay splinted and metal splinted) using 3 impression materials: vinyl polysiloxane putty/light body with a metal stock tray and polyether medium consistency and vinyl polysiloxane regular body were used with a custom aluminum tray. A master cast with 4 parallel implant abutment analogs and a framework were fabricated. Nine groups (n=5) were tested. The gap measurement method employed was just one titanium screw tightened to the framework. Group’s measurements were analyzed using LeicaQWin software that received the images of a video camera coupled to a stereomicroscope at x100 magnification. The results were statistically analyzed with Kruskal-Wallis One Way ANOVA on Ranks test followed by Dunn's Method, !=.05. Under the conditions of this study the following conclusions could be drawn: no significant difference was detected among Master Cast (31.63 !m), Squared Impregum (38.03 !m), Sandblasted-Adhesive Squared Impregum (46.80 !m), Index (45.25 μm) and Modified Squared techniques (51.20 μm) (P=.05), being the elected. Due to the worst results with the techniques Squared Express Regular (151.21 μm) and Sandblasted-Adhesive Squared Express Regular (136.59 μm), the Express regular body impression material should not be used, and then chosen to be used Impregum Soft medium consistency with custom tray. If the dentist wishes to perform the technique with splinted copings (Metal Splinted = 68.55 !m and Duralay Splinted = 165.03 !m), the splint should be made with bars of metal. The impression technique using sandblasted-adhesive squared... (Complete abstract click electronic access below)

Orientador: Rodrigo Máximo de Araújo
Coorientadora: Samia Carolina Mota Cavalcanti Sacorague
Banca: Paula Carolina Komori de Carvalho
Banca: Fernanda de Cássia Papaiz Gonçalves
Resumo: A otimização do tempo reabilitador é um benefício direto a saúde do paciente, pois previne o mesmo do contato com possíveis contaminações e ambientes que lhe causem estresse. Isso pode ser viabilizado pelo desenvolvimento de técnicas que diminuam etapas de execução de um determinado tratamento. Pensando nisso, esse trabalho tem por objetivo avaliar a desadaptação marginal de copings em liga de cobalto-cromo (Co-Cr) através da técnica da réplica de silicone (2D) e avaliação por varredura digital (3D), em 24 dentes humanos unirradiculares, com retentores intraradiculares (RIR) em Co-Cr, cimentados com cimento de fosfato de zinco. Divididos em dois grupos, ambos com término marginal em ombro 130º: grupo A obtidos pelo método convencional, com execução de RIR primeiro, para depois coping com retentor já cimentado e grupo B de moldagem única para obtenção de RIR e coping. Os resultados foram submetidos a uma análise do teste t e de variância ANOVA. A técnica da réplica de silicone, demonstrou as seguintes médias de valores marginais: 83,77±51,84μm (grupo A) e 77,09±31,65μm (grupo B) p=0,4477 E a varredura digital, os resultados positivos revelaram que as médias de todas as superfícies encontraram-se acima de 50 μm; e os negativos: revelaram que as médias encontraram-se abaixo de 100 μm. Este estudo concluiu que é possível obter RIR e coping através de moldagem única
Abstract: The optimization of the clinical appointment is a direct benefit to the health of the patient, because prevents it from the contact with possible contaminations and environments that cause stress. This can be possible by the development of techniques that may decrease the execution stages of a treatment. With this in mind, the aims of this study is to investigate the marginal adaptation of Cobalt-Chromium alloy (Co-Cr) copings through silicone replica technique (2D) and digital evaluation (3D) in 24 human single rooted teeth with post-and-core in Co-Cr, cemented with zinc phosphate. Divided in to two groups, both having shoulder 130 degrees as marginal type: group A by the conventional method, impression and cementation of Co-Cr post-and-core first and then impression for the coping and group B single impression for coping and post and core. The results were analyzed by test t and one-way ANOVA. The silicone replica technique showed the following mean marginal values: 83.77 ± 51.84 μm (group A) and 77.09 ± 31, 65 μm (group B) p= 0,4477. The digital protocol, in the positive results revealed that the averages of all surfaces were above 50 μm; and the negatives: revealed that the averages were below 100 μm. This study concluded that it is possible to obtain post-and-core and coping through a single impression technique
Mestre

Contents. Properties of dental materials. Amalgam. Composite resins—constituents and properties. Composite resins—practical points. Enamel and dentine bonding. Dentine-adhesive systems (dentine bonding agents). Glass ionomers. Other glass ionomer/composite-based products. Cements. Impression materials. Impression techniques. Casting alloys. Wrought alloys. Dental ceramics. CAD/CAM. Denture materials—acrylic resins. Denture materials—rebasing. Safety of dental materials.

The aim of this chapter is to cover the management of more complicated clinical problems associated with children and adolescents: tooth discolouration, inherited enamel and dentine defects, hypodontia, and tooth surface loss. As there is considerable overlap in the application of the various restorative techniques, the chapter is divided into two parts. The first outlines the clinical steps involved in the various procedures, while the second covers the more general principles of management of particular dental problems. It is not the remit of this chapter to cover advanced restorative dentistry in detail, but many of the techniques and indications used in children are the same as those for adults (Boxes 11.1 and 11.2). With the aid of some clinical examples, eight of the restorative procedures will be described in simple stages. Omitted from this list are the stages involved in the provision of full crown restorations and bridgework, which are the specific remit of a restorative dentistry textbook. However, the provision of porcelain veneers, more commonly associated with adult patients, will be mentioned briefly. This technique involves the daily placement of carbamide peroxide gel into a custom-fitted tray on either the upper or the lower arch. As the name suggests, it is carried out by the patient at home and is initially done on a daily basis. • Mild fluorosis. • Moderate fluorosis as an adjunct to hydrochloric acid–pumice micro-abrasion. • Yellowing of ageing. • Single teeth with sclerosed pulp chambers and canals. • Selective bleaching for aesthetic purposes. • Upper impression and working model. • Soft mouthguard—avoiding the gingival tissues. • 10% carbamide peroxide gel. 1. Take an alginate impression of the arch to be treated and cast a working model in stone. 2. Relieve the labial surfaces of the teeth by about 0.5mm and make an acrylic pull-down vacuum-formed splint as a mouthguard with or without reservoirs for bleaching agent on the teeth requiring lightening. The splint should be no more than 2mm thick and should not cover the gingival tissues. It is only a vehicle for the bleaching gel and is not intended to protect the gingivae.

This chapter investigates the materials used in dentistry today. This includes the properties of dental materials, amalgam, and composite resins. Enamel and dentine bonding are discussed, along with dentine-adhesive systems, glass ionomers and composite-based products, and cements. Impression materials and techniques are considered, along with casting alloys, wrought alloys, dental ceramics, and computer-aided design (CAD) and computer-aided manufacture (CAM). The chapter concludes with a look at denture materials, from acrylic resins to rebasing, and the safety of dental materials.

Dental material science can be a daunting subject for most dentists, given its origins in the pure sciences of physics and chemistry. Combining this with human biology, and trying to see through the fog of material manu­facturers’ commercial claims, can make it seem like a truly mystifying subject. It is important that any student of material sciences maintains a critical eye and an evidence- based approach when it comes to material selection and use. Today we are lucky enough to work with the most advanced dental materials we have ever had. But simply having such materials at your dis­posal does not ensure success. Clinical procedural techniques are often the prime focus in restorative dentistry; however, to achieve optimal aesthetics, function, and longevity from restorations, a clear under­standing of material sciences is required. Ancient Roman engineers clearly understood this concept when con­structing Rome. They had to work within the limitations imposed by the materials they had at their disposal. However, the longevity and solidity of the impressive infrastructure we see today can be attributed to their expertise in exploiting the unique properties of the material resources they had available. The Romans perfected concrete production (based on volcanic ash and lime reacting with seawater to form tobermorite crystals) to yield a water- hardening material, so durable and resistant to cracks that modern- day concrete (based on Portland cement) is still considered weaker. It can be argued whether operator skill or advancements in dental ma­terials have resulted in improvements in restorative dentistry. However, few would disagree that it is the combination of good operator skill and appropriate use of dental materials that is the key for successful long-term dentistry. Key topics include: ● Adhesive dentistry concepts ● Understanding material physical properties ● Elemental make- up of materials ● Manufacturing processing of materials ● Biocompatibility ● Appreciation of setting reactions and working time ● Appreciation of material aesthetic and optical properties.

A child’s future perceptions and expectations are likely to be conditioned by early experiences of dental treatment. Just under half of all children report low to moderate general dental anxiety, and 10–20% report high levels of dental anxiety. Montiero et al. (2014) indicate that the prevalence of needle phobia may be as high as 19% in 4- to 6-year-olds. Davidovich et al. (2015) reflected that, for general practitioners and specialists alike, Local anaesthetic (LA) injection for an anxious child was the most stressful procedure regardless of the operator’s age, gender, or years of professional experience. Despite impressive reductions in caries in children in recent years, there still exists a social gradient with inequalities in experience of dental disease, and there remains a significant cohort of children for whom extractions and restoration of teeth are necessary. Aside from emerging restorative strategies that do not require LA (e.g. atraumatic restorative technique or placement of preformed metal crowns using the Hall technique), effective and acceptable delivery of LA remains an important tool to enable successful operative dental treatment to be carried out comfortably for child patients. Effective surface anaesthesia prior to injection is very important as a child’s initial experience of LA techniques may influence their future perceptions and help in establishing trust. Cooling tissues prior to injection has been described but is rarely used, and surface anaesthesia is generally achieved with intra-oral topical agents. Although the main use of topical agents is as a pre-injection treatment, they have been used as the sole means of anaesthesia for some procedures including the extraction of mobile primary teeth. It is possible to achieve a depth of 2–3mm of anaesthesia if topical agents are used correctly: • the area of application should be dried • topical anaesthetic agent should be applied over a limited area • the anaesthetic agent should be applied for sufficient time. In the UK 5% lidocaine (lignocaine) and 18–20% (17.9%) benzocaine gels are the most commonly used agents. Benzocaine topical anaesthetic gel is not recommended for use on children under 2 years old because of an increased risk of methaemoglobinaemia.

Abstract The design of a novel scanning apparatus used for digitizing dental impression molds is presented. The apparatus consists of a four-degree-of-freedom hybrid spherical linkage capable of moving the dental mold relative to a laser scanner along a curved path in the specified orientations. Since closed form inverse kinematics solutions are not available for the multiple degree-of-freedom spatial mechanism in question, symbolic and numerical computation techniques are used extensively for kinematics analysis, dimension design, and optimization. In addition, mechanical design and simulation software (Pro/Engineer & Pro/Mechanica), as well as the rapid prototyping machines are used to reduce the development cost and cycle time.

Dentist, follow root canal therapy to treat teeth with pulpal involvement due to dental caries or as a result of trauma. In order to restore fractured and broken down teeth internal reinforcement is required in the form of a post-core restoration. The post extends into the root canal space and provides retention for the core, which subsequently helps to provide a foundation for the crown restoration. For the treatment procedure, post, core and crown are casted by an indirect procedure by taking the measurements from patient’s tooth in the form of impressions. These impressions are then converted into solid gypsum casts and then wax patterns are developed in order to facilitate casting by the lost wax technique. The final shape of the core and crown and success of the treatment entirely depends upon the skill of the dental technician and involves a number of variables in impressioning, cast poring and wax pattern fabrication. The treatment can be further simplified by making a prototype model of the post, core and the crown by taking the dimensions from the patient’s tooth. This paper presents four prototype models prepared from the solid model of the original tooth and three restored tooth.

A reliable tool for assessing the extent of human enamel wear would be useful to dental practitioners. Current in-vivo methods for determining tooth wear are largely qualitative in nature or depend on measurements taken from tooth impressions, which is very time consuming. The aim of this work was to investigate the feasibility of using ultrasound to measure enamel thickness with a view to developing an in-vivo tool for enamel wear assessment. Three different ultrasonic techniques were used in-vitro to take measurements of enamel on extracted teeth. The first used a focusing immersion transducer (25 MHz) and a time of flight approach to obtain enamel thickness. The other two techniques used planar contact probes (10 MHz), the first with a time of flight approach and the second with a resonance method to determine enamel thickness. The results were compared with direct measurements of sectioned teeth. All three methods showed good correlation with these measurements. The contact probe technique was the easiest measurement to carry out, which would also be the simplest to implement in a measurement tool. While the resonance measurements obtained were good, the time of flight approach was thought to be most likely to obtain accurate repeatable measurements.

This report summarizes a review of the scientific foundations of bitemark analysis conducted by the National Institute of Standards and Technology (NIST). Bitemark analysis typically involves examining patterned injuries left on a victim or object at a crime scene, identifying those injuries as bitemarks, and comparing those marks with dental impressions from a person of interest. This review specifically focuses on pattern injuries found on human skin. Over 400 sources were considered via literature searches and input from previous efforts by the National Institute of Justice Forensic Technology Center of Excellence. Our NIST review also utilized input from an October 2019 Bitemark Thinkshop organized by the Center for Statistics and Applications in Forensic Evidence (CSAFE) where experts and stakeholders associated with bitemark analysis were convened to discuss key issues. Based on this input, our study found a lack of support for three key premises of the field: 1) human dentition is unique at the individual level, 2) this uniqueness can be accurately transferred to human skin, and 3) identifying characteristics can be accurately captured and interpreted by analysis techniques. Furthermore, our review noted a lack of consensus among practitioners on the interpretation of bitemark evidence as well as thoughts on how to move the field forward. If the field seeks to advance, the key takeaways provided in this review are starting points for areas needing improvement, not an exhaustive list of specific shortcomings.