Does occlusal morphology of artificial teeth improve chewing of removable dentures wearers? A systematic review and meta-analysis.

PURPOSE: This systematic review aimed to verify whether anatomic, semi-anatomic, or nonanatomic occlusal morphology of artificial teeth improves the masticatory function of complete or removable partial denture wearers. MATERIALS AND METHODS: According to the PICO strategy, six databases and the grey literature were searched to identify randomized (RCT) and non-randomized clinical trials (N-RCT) comparing masticatory function, in terms of masticatory performance and efficiency, and muscle activity as primary outcomes; and patient-reported results (O) in individuals using removable dentures (P) with different occlusal morphologies of artificial teeth (I/C). Masticatory ability, satisfaction with the prosthetic treatment, and oral health-related quality of life (OHRQoL) were evaluated as secondary outcomes. Risk of bias was assessed using the Cochrane risk-of-bias tool for randomized trials (RoB 2.0) for RCT and Risk of Bias for non-randomized studies with intervention (ROBINS-I) for N-RCT studies. Meta-analyses were performed to compare primary outcomes and masticatory ability between the occlusal morphologies of artificial teeth of complete or removable partial dentures (α = 0.05). Certainty of the evidence was verified using the GRADE approach. RESULTS: Eleven studies (seven RCTs and four N-RCTs) were included. The risk of bias was considered low for two studies, some concerns for five, and high for the last four studies. Meta-analyses showed that removable partial dentures with anatomic artificial teeth improved masticatory efficiency for carrot chewing (MD 6.31; 95% CI [3.39, 9.22], I2 = 0%). However, masseter and temporal muscle activities increased when removable partial dentures with nonanatomic teeth were used (MD -756.97; 95% CI [-892.25, -621.68], I2 = 100%). Masticatory ability was not influenced by occlusal morphology during chewing of all foods in complete denture users: Carrot (MD -0.88, 95% CI [-8.98, 7.23], I2 = 57%); sausage (MD -8.86, 95% CI [-23.05, 5.33], I2 = 71%); apple (MD -5.78, 95% CI [-28.82, 17.26], I2 = 87%); and cheese (MD -4.16, 95% CI [-15.14, 6.82], I2 = 62%). The certainty of evidence for all evaluated outcomes was very low, mainly due to very serious problems found in the parameters of inconsistency, indirectness, and imprecision. CONCLUSIONS: Despite the very low certainty of evidence, the occlusal morphology of artificial teeth influences masticatory function. Anatomic teeth improved the masticatory efficiency and muscle activity of removable partial denture wearers. Nonanatomic teeth increased temporal and masseter muscle activity, which negatively affected chewing in removable partial denture users. However, patients using complete dentures with anatomic and semi-anatomic teeth presented similar masticatory ability.

A comparative evaluation of student experience with artificial teeth used in pre-clinical fixed prosthodontics post-core undergraduate teaching programs.

INTRODUCTION: Research is lacking in the use of artificial teeth for post-core techniques in undergraduate fixed prosthodontics pre-clinical education. The aim of this study was to compare the reasons for selection and explore the direct student experiences with artificial teeth used in two pre-clinical fixed prosthodontics post-core technique teaching programs conducted in consecutive years. MATERIALS AND METHODS: Fourth year undergraduate dental students who had completed the fixed prosthodontics pre-clinical program were invited to complete an anonymous online surveys. Information was requested on the use and direct student experiences with artificial and natural teeth for post-core techniques. Quantitative data was summarised and qualitative data was clustered into topics. The reasons for selection and use of artificial and natural teeth were compared within and between the two programs. RESULTS: 36% of 70 respondents in 2020 chose to use one or more artificial teeth for the post-core exercises in the pre-clinical program compared with 94% of 77 respondents in 2021 (p < .05). The use was driven by difficulty in sourcing appropriate natural teeth. Respondents reported "ease of use" as the dominant positive user experience with the main negatives being "unrealistic simulation of natural teeth" and "different surface texture/feel when cutting." CONCLUSION: Artificial teeth were reported to provide an appropriate and realistic simulation experience compared with extracted natural teeth and were easier to source. Students focussed on the practicalities of sourcing artificial teeth, associated costs and ease of use ahead of conceivable educational benefits. Cost limited the more widespread use of artificial teeth.

Analysis of the Facial Measurements and Dental Arch Dimensions for the Construction of Dental Prostheses among Adult Yemenis.

AIM: To investigate the dental arch dimension (width, length, and height) and facial measurements including inner-canthal width (ICW), bizygomatic width (BZW), inter-alar width (IAW), and mouth width (MW), and to assess the correlation between these facial measurements and dental arch width (canine width [CW], inter-first premolar width [I1PW], and inter-first molar width [I1MW]), to establish a preliminary reference for artificial teeth selection in Yemeni adult. MATERIALS AND METHODS: The study included 80 individuals (40 males and 40 females) with symmetrical faces and normal class I occlusion ranging in age from 20 to 35. Maxillary and mandibular stone casts were made for each individual. The dimensions of dental casts and facial measurements, including ICW, BZW, IAW, and MW, were assessed using a digital caliper. The collected data were analyzed by using the SPSS software program. The descriptive statistics for each measurement were made. Differences between males and females were tested using an independent-sample t-test with p-values below 0.05 considered significant. Pearson correlation coefficient between facial measurements and dental arch width was also done. RESULTS: Most dental arch dimensions and facial measurements exhibited larger mean values in the male than in the female group, with the greatest significant difference in the maxillary dental arch width and the lowest in mandibular dental arch length. A highly significant correlation is observed between ICW and maxillary canine width (CW) (r = 0.318, p = 0.004). In contrast, no significant correlation between dental arch width and BZW, IAW, and MW is shown. CONCLUSIONS: Within this study's limitations, the ICW can determine the ideal dimension of the artificial teeth in the anterior maxillary arch. While the other facial parameters, including BZW, IAW, and MW, cannot be used for artificial teeth selection in Yemeni populations. CLINICAL SIGNIFICANCE: The findings of this study established a reference database of facial measurements and their correlation to dental arch and teeth width in Yemeni populations. So, it can be implemented in artificial teeth and dental prostheses design and construction.

Orthodontic shear bond strength and ultimate load tests of CAD/CAM produced artificial teeth.

OBJECTIVES: To investigate whether artificial CAD/CAM processed (computer-aided design/manufacturing) teeth could be a feasible option for the production of dental in vitro models for biomechanical testing. MATERIAL AND METHODS: Disks (n = 10 per group) made from two different CAD/CAM-materials, one fiber-reinforced composite (FRC; Trinia, Bicon) and one polymethylmethacrylate-based resin (PMMA; Telio CAD, Ivoclar Vivadent), as well as bovine teeth (n = 10), were tested for their shear bond strength (SBS) and scored according to the adhesive remnant index (ARI). In addition, CAD/CAM-manufactured lower incisor teeth were tested for their ultimate load (Fu). RESULTS: With regard to SBS, both PMMA (17.4 ± 2.2 MPa) and FRC (18.0 ± 2.4 MPa) disks showed no significant difference (p = 0.968) compared to bovine disks (18.0 ± 5.4 MPa). However, the samples differed with regard to their failure mode (PMMA: ARI 4, delamination failure; FRC: ARI 0 and bovine: ARI 1.6, both adhesive failure). With regard to Fu, FRC-based teeth could withstand significantly higher loads (708 ± 126 N) than PMMA-based teeth (345 ± 109 N) (p < 0.01). CONCLUSION: Unlike PMMA-based teeth, teeth made from FRC showed sufficiently high fracture resistance and comparable SBS. Thus, FRC teeth could be a promising alternative for the production of dental in vitro models for orthodontic testing. CLINICAL RELEVANCE: CAD/CAM-processed teeth made from FRC enable the use of standardized geometry and constant material properties. Using FRC teeth in dental in vitro studies has therefore the potential to identify differences between various treatment options with rather small sample sizes, while remaining close to the clinical situation.

Effect of an endodontic e-learning application on students' performance during their first root canal treatment on real patients: a pilot study.

BACKGROUND: E-learning has found its way into dental teaching in general and endodontic teaching in particular. The present study aimed to implement a newly developed multimedia learning application and assess its effect on students' first root canal treatment on real patients. With the COVID-19 outbreak, the application's performance was investigated during the pandemic. METHODS: A total of 138 students in the initial clinical endodontic course participated in this study. The control group (n = 49) followed the traditional curriculum, including practice on artificial teeth and face-to-face teaching events. In addition to the traditional curriculum, test group 1 (n = 54) had access to an endodontic e-learning application containing videos demonstrating artificial teeth and patient cases. With the COVID-19 outbreak, test group 2 (n = 35) had no face-to-face teaching; however, endodontic patient treatments were included. The quality of students' first root canal treatment on real patients was compared using performance and radiographic assessment items. Statistical analysis was done using Kruskal-Wallis and chi-squared tests. Test groups received a questionnaire to assess the learning application. Test group 2 also completed a COVID-19-specific survey to measure students' perceptions of how the pandemic affected their endodontic education. RESULTS: The results of endodontic treatments were significantly better for test group 1 (P < 0.001) and 2 (P < 0.001) than for the control group. Likewise, there were significantly fewer treatment errors in test group 1 (P < 0.001) and 2 (P < 0.001). No significant differences were found between test groups 1 and 2. Students of the test groups positively evaluated the e-learning application. Students of test group 2 expressed their fear of negative impacts on their course performance. CONCLUSION: The e-learning application was well-received and seemed to improve endodontic education. The results imply that the quality of education may be maintained by implementing e-learning to compensate for face-to-face teaching. As no difference was found between online and face-to-face teaching, students' and lecturers' concerns that endodontic education is suffering because of the pandemic may be eased.

Fatigue behaviour of dental crowns made from a novel high-performance polymer PEKK.

OBJECTIVES: The aim of this study was, firstly, to analyse the long-time fatigue behaviour of crowns constructed from a novel polyetherketoneketone (PEKK) polymer, using artificial prepared teeth. Secondly, to determine the effect of the material's stiffness that used as an artificial prepared tooth on the fatigue life of the PEKK crowns in comparison to human prepared teeth. METHODS: Veneered crowns with a PEKK framework were constructed on three different prepared teeth: artificial polymethyl methacrylate (PMMA) teeth, artificial CoCr teeth and extracted human teeth. As far as applicable, the loading protocol was based on EN ISO 14801:2007 for fatigue testing of dental implants. After initial static fracture tests on three specimens from each group, the remaining crowns were loaded with different force levels until fracture or until 2 × 106 loading cycles were reached. The number of loading cycles until failure was recorded. Wöhler curves were created to display the fatigue limits. RESULTS: Static fracture limits as well as fatigue limits differed for all three core materials. The static fracture tests resulted in fracture limits of 1200 (± 293) N for the PMMA group, 1330 (± 219) N for the CoCr group and 899 (± 96) N for the human tooth group. Fatigue limits of 770 N, 840 N and 720 N were determined for the PMMA group, CoCr group and human tooth group, respectively. CONCLUSIONS: The determined fatigue limit of above 720 N (depending on the core material) is sufficiently high and a good performance of this crown material is expected in the clinical loading life. The results showed that using artificial teeth instead of natural teeth for fatigue testing of crowns might result in an overestimation of the fatigue limits of the crown material. CLINICAL RELEVANCE: PEKK-made crowns offer a stable and priceworthy treatment for patients, in particular those that suffer from metal allergy.

Suitability of different tooth replicas for endodontic training: perceptions and detection of common errors in the performance of postgraduate students.

AIM: To compare the perceptions of students when using five different tooth replicas and to detect common errors in the performance of students that might be attributed to a specific type of tooth replica. METHODOLOGY: Five groups (n = 10 each) of artificial first maxillary molars (DEPT, DRSK, Nissin, DENTALIKE and TrueTooth) were used. All 50 teeth were mounted individually in opaque containers, distributed in 10 packages containing a sample from each with an assigned random order for students to perform root canal treatments. Ten postgraduate students each performed a root canal treatment on the five replicas, in the assigned order, and completed a satisfaction questionnaire. Three trained and calibrated endodontic educators, each with more than 15 years of experience, evaluated their performance using a grading rubric and completed a questionnaire to detect common errors attributed to a specific tooth replica. Inter-rater reliability was calculated with the interclass correlation coefficient for both consistency and absolute agreement. A two-way related measures anova was used to assess the interaction amongst evaluators and tooth groups on the average scores of students. Post hoc T3 Dunnet was used to compare groups. The perceptions of students amongst groups were compared with chi-square and linear-by-linear association tests. RESULTS: Inter-rater reliability was very high for both consistency (ICCC = 0.939; 95% confidence interval (CI) 0.902-0.964) and absolute agreement (ICCA = 0.940; 95% CI 0.904-0.965). No significant differences were found amongst the ratings of evaluators; however, students performed differently when using the various tooth replicas (P < 0.05). Overall, 60% of students preferred the DRSK replica for root canal treatment training purposes, followed by DENTALIKE (30%). The least preferred was TrueTooth (70% responses) due to its complex anatomy and poor resistance to instruments and heat pluggers. Evaluators detected several common errors in specific tooth replicas and preferred tooth replicas manufactured based on microCT scans of natural teeth. CONCLUSIONS: Tooth replicas manufactured based on microCT scans of natural teeth (TrueTooth and DENTALIKE) had much better acceptance amongst evaluators, although students rated and performed less well in TrueTooth replicas due to their greater level of difficulty.

Morphological comparison of artificial teeth position utilising denture space in glossectomy patients.

OBJECTIVE: This study aimed to compare the denture space of edentulous glossectomy patients with that of a control group from the perspective of artificial teeth positioning by using three-dimensional techniques. BACKGROUND: It is known that the shape of the denture space may be affected by tongue resection or reconstruction. However, the details of artificial teeth positioning in these patients remain unclear. MATERIALS AND METHODS: Six edentulous glossectomy patients aged 73-83 years and six normal participants aged 74-85 years participated in the study. Piezography was used to elucidate the characteristics of the denture space. For visualisation, piezographic records were scanned using cone beam computed tomography and the data were converted into stereolithographic format. Three-dimensional images of piezographic records were then constructed. Bucco-lingual widths of the mandibular occlusal surface were reproduced, and the camber line of the occlusal surface was set so as to simulate the position of the artificial teeth. The maximum chord of the occlusal surface on the left and right sides was recorded and measured. The discrepancy and ratio of the larger chord to the smaller chord between the right and left sides was calculated and subjected to statistical analyses using the Mann-Whitney U test. RESULTS: There were significant differences in discrepancy and ratio between the left and right in the control group and the glossectomy patients (P Ë‚ .01). The glossectomy patients showed a greater discrepancy and ratio than the control group. CONCLUSIONS: The simulated artificial teeth positions on the occlusal surface between the right and left side were asymmetric in glossectomy patients.

Two-body Wear and Hardness of New Generation Artificial Resin Teeth.

The purpose of this study was to evaluate two-body wear and hardness of new generation artificial resin teeth. Ten specimens of four different artificial resin teeth (nanofill composite, nanohybrid composite, microfiller reinforced acrylic and highly modified acrylic) were prepared. Specimens were thermodynamically loaded in a dual-axis chewing simulator (50N, 240,000 cycles, 1.6 Hz, 5/55°C thermocycle). The wear loss was analyzed by using plaster replicas and 3D laser scanner. Vickers hardness was determined before and after thermodynamic loading. Mean Vickers hardness values of highly modified acrylic resin teeth were statistically significantly lower than nanohybrid composite (p⟨0.001), nanofilled composite (p⟨0.001) and microfiller reinforced acrylic resin teeth (p⟨0.001). Mean wear loss of highly modified and microfiller reinforced acrylic resin teeth were statistically significantly lower than nanohybrid composite (p⟨0.001) and nanofilled composite (p⟨0.001) resin teeth. There was a statistically significant difference in wear among the materials. The correlation between hardness and wear was not statistically significant.

3D printed replicas for endodontic education.

AIM: To assess the feasibility of producing artificial teeth for endodontic training using 3D printing technology, to analyse the accuracy of the printing process, and to evaluate the teeth by students when used during training. METHODOLOGY: Sound extracted human teeth were selected, digitalized by cone beam computed tomography (CBCT) and appropriate software and finally reproduced by a stereolithographic printer. The printed teeth were scanned and compared with the original ones (trueness) and to one another (precision). Undergraduate dental students in the third and fourth years performed root canal treatment on printed molars and were subsequently asked to evaluate their experience with these compared to real teeth. RESULTS: The workflow was feasible for manufacturing 3D printed tooth replicas. The absolute deviation after printing (trueness) ranged from 50.9 to 104.3 µm. The values for precision ranged from 43.5 to 68.2 µm. Students reported great benefits in the use of the replicated teeth for training purposes. CONCLUSION: The presented workflow is feasible for any dental educational institution who has access to a CBCT unit and a stereolithographic printer. The accuracy of the printing process is suitable for the production of tooth replicas for endodontic training. Undergraduate students favoured the availability of these replicas and the fairness they ensured in training due to standardization.

Evaluation of Shear Bond Strength of Three Different Acrylic Resin and Artificial Denture Teeth with and without Monomer Application.

AIM: To compare and evaluate the shear bond strength of the tooth-denture base junction when three different commercially available acrylic resin base bonded to acrylic teeth with and without application of methyl methacrylate monomer on ridge lap area. MATERIALS AND METHODS: A three-stepped cylindrical shaped die was customized. Sixty samples were fabricated with heat cure and self-cure acrylic resin with and without monomer application. A total of 60 samples were divided into three groups and six subgroups. • Group A-Twenty samples of Trevlon-HI heat-activated acrylic resin. • Subgroup A1-Ten samples of acrylic teeth bonded with Trevlon-HI heat-activated acrylic resin with the application of monomer on ridge lap area. • Subgroup A2-Ten samples of acrylic teeth bonded with Trevlon-HI heat-activated acrylic resin without application of monomer on ridge lap area. • Group B-Twenty samples of Trevalon heat-activated acrylic resin. • Subgroup B1-Ten samples of acrylic teeth bonded with Trevlon heat-activated acrylic resin with the application of monomer on ridge lap area. • Subgroup B2-Ten samples of acrylic teeth bonded with Trevlon heat-activated acrylic resin without application of monomer on ridge lap area. • Group C-Twenty samples of Trevlon-RR self-activated acrylic resin. • Subgroup C1-Ten samples of acrylic teeth bonded with Trevlon-RR self-activated acrylic resin with the application of monomer on ridge lap area. • Subgroup C2-Ten samples of acrylic teeth bonded with Trevlon-RR self-activated acrylic resin without monomer application on ridge lap area. RESULTS: Samples obtained from high impact heat cure acrylic resin with monomer application shows higher bond strength when tested under the universal testing machine. CONCLUSION: With and without monomer application on high impact polymethylmethacrylate (PMMA) resin and Heat cured resin it was found that high impact shows better bond strength. Trevlon HI monomer shows a greater increase in strength due to the presence of cross-linking agents. CLINICAL SIGNIFICANCE: The incorporation of mechanical surface treatments followed by monomer application significantly influences the bonding between denture teeth and denture base resin.

Evaluation of the Efficacy of Various Topical Fluorides on Enamel Demineralization Adjacent to Orthodontic Brackets: An In Vitro Study.

AIM: White spot lesions (WSLs) occur frequently after fixed orthodontic treatment. This in vitro study was undertaken to compare the efficacy of 2.26% fluoride varnish, 1.23% APF gel, 0.21% fluoride toothpaste and 0.04% sodium fluoride mouthwashes in preventing enamel demineralization around orthodontic brackets in extracted premolars. MATERIALS AND METHODS: The sample for this study included 100 premolars free of caries and enamel cracks. They were divided into five groups of 20 samples each. Group 1 (FV): light-curable Fluoride varnish (Clinpro™ XT 3M ESPE, Pymble, New South Wales, Australia), group 2 (FG): 1.23% APF gel (Patterson NE. International, USA), group 3 (FTP): 0.21% w/w sodium fluoride toothpaste with tri-calcium phosphate (Clinpro™ Tooth Crème, 3M ESPE, Australia), group 4 (FMW): sodium fluoride 0.044% (w/v) mouthwash (Colgate® Phos-Flur® Ortho Defense Rinse, Colgate-Palmolive, NY) and group 5 (C): control. The samples were subjected to laboratory pH cycling. The demineralization changes in the enamel were assessed before the start of the experiment and after 14 days. RESULTS: There was a significant change in the mean Diagnodent score value (p <0.001) in all groups from day 1-day 14. The mean values were significantly different among groups at day 1 (p = 0.002), day 14 (p = 0.001) and also the change from Day 1 to Day 14 was significantly different among Groups (p = 0.001). The least change in the mean value from baseline to 14 days was seen in group 1 (FV) followed by group 3 (FTP), group 2 (FG), and group 4 (FMW) and then the group 5 (C). CONCLUSION: All the topical fluorides tested were able to reduce the demineralization when compared to the control group under similar testing conditions, but to varying degrees. light-curable fluoride varnish outperformed all the topical fluorides followed by 0.21% w/w dodium fluoride toothpaste with tri-calcium phosphate, 1.23% Acidulated phosphate fluoride gel and sodium fluoride 0.044% (w/v) mouthwash. The control group where no topical fluoride was applied showed the least resistance to demineralization. CLINICAL SIGNIFICANCE: Within the limitations of this study, routine application of light cured fluoride varnish (Clinpro) can be recommended to prevent enamel demineralization to prevent white spot lesions in patients receiving orthodontic treatment.

A Comprehensive Review on the Errors That occur during Ideal Teeth Arrangement for Complete Denture Prosthesis.

AIM: The aim of this article is to present a comprehensive review and a classification system on the various errors that occur during the ideal arrangement of artificial teeth for complete denture prosthesis. MATERIALS AND METHODS: Assessment of various classification systems presented for errors in artificial tooth arrangement and identifying the lacunae in each system. RESULTS: A comprehensive review and a classification system on the various errors that occur during the ideal arrangement of artificial teeth for complete denture prosthesis have been presented. CONCLUSION: This classification system is aimed toward dental students and dental practitioners to aid in the arrangement of artificial teeth for complete denture prosthesis. CLINICAL SIGNIFICANCE: The proposed classification system helps the operator to identify the various errors which may occur during the arrangement of artificial teeth for complete denture prosthesis. It also aids in providing a detailed insight into the role played by artificial teeth in restoring the form and function of completely edentulous patients.

[Algorithm for artificial teeth size estimation according to face morphological features in patients with complete adentia]. / Algoritm opredeleniia razmerov iskusstvennykh zubov po morfometricheskim parametram litsa u liudei s polnoi adentiei.

The aim of the study was to improve the prosthetic treatment of patients with complete absence of teeth, taking into account the development of an algorithm for determining the size of artificial teeth by the morphometric parameters of the face. The study involved 76 elderly and senile adults with a full adentia of permanent teeth, who turned to the clinic for a prosthetic treatment. The results of examination and orthopedic treatment of this category of patients made it possible to develop an algorithm for determining the size of artificial teeth during prosthetics of dentition defects, taking into account the original correction factors obtained by calculation and analytical methods using mathematical-graphic modeling. The algorithm is based on the optimal ratio of diagonal facial parameters on both sides and the sum of the mesial-distal dimensions of 14 artificial teeth on the upper jaw, taking into account the correction factor of 2.2. The sum of the width of the artificial teeth of the frontal part on the upper jaw correlates with the total width of the crowns of 14 artificial teeth, taking into account the correction coefficient of 2.45. The value of the intermaxillary correction factor at a ratio of the width of 14 artificial teeth on the upper jaw to the similar dimensional characteristics of artificial teeth on the lower jaw is 1.07. Thus, to determine the size of artificial teeth in the design of denture prostheses, it is mathematically tested and clinically justified the advisability of using diagonal facial parameters and corresponding original correction factors.

Use of artificial primary teeth for endodontic laboratory research: experiments related to canal length determination.

BACKGROUND: Due to the scarcity of exfoliated/extracted human primary teeth with complete roots, artificial teeth were developed as an alternative to be used for educational and laboratory research purposes. This study aimed to assess the feasibility of using artificial primary teeth for conducting laboratory research through an experiment related to canal length determination, comparing artificial teeth with natural teeth. METHODS: Thirty anterior and 21 posterior artificial teeth, and the same number of natural primary teeth were selected. After preparing the access cavity, the root canal length was determined by two examiners twice using three different methods: radiography and two electronic apex locators. Then, the actual root canal length was measured by inserting a K-file up to the apical foramen (reference standard). Accuracy was calculated using Bland-Altman analysis and intraclass correlation coefficient (ICC). The inter- and intra-examiner reproducibility was also calculated using the ICC. RESULTS: The methods using the electronic apex locators showed better accuracy in both artificial and natural teeth. Trends observed with artificial primary teeth were similar to those observed with natural teeth, except for the results in artificial anterior teeth. CONCLUSIONS: The model of artificial teeth might be a good alternative for educational purposes; however, improvements are necessary to employ these teeth for research purposes when considering experiments for canal length determination.

Students' perceptions of pre-clinical endodontic training with artificial teeth compared to extracted human teeth.

PURPOSE: Artificial teeth have several advantages in pre-clinical endodontics training. This study aimed to compare artificial resin teeth with extracted human teeth, from a student's perspective, during a pre-clinical undergraduate endodontic course for three consecutive academic years (2011-2014). METHODS: At the end of the course, students completed a questionnaire that included questions about their perceptions of the difficulty of artificial teeth vs. natural teeth and ranked the perceived advantages of artificial teeth. RESULTS: Participants expressed that all procedures, except obturation, were more difficult to perform on artificial teeth than on natural teeth, a result that was due to the hardness of the resin. They ranked the fairness and availability as the best advantages. CONCLUSION: Artificial teeth have multiple advantages but cannot replace natural teeth. The physical characteristics through the manufacturing material of artificial teeth should be enhanced to increase wider use and acceptance.

Effect of Cast Modification on Linear Dimensional Change of Acrylic Tooth Position Following Maxillary Complete Denture Processing.

PURPOSE: To investigate the effect of different cast modifications on the vertical and horizontal tooth position following maxillary complete denture processing. MATERIALS AND METHODS: A total of 60 maxillary master casts were prepared and arranged in six groups (n = 10). Variation in modifications between study groups 1 through 6 were as follows: no modification, butterfly post palatal seal preparation only, butterfly post palatal seal preparation with 10 mm wide/4 mm deep box, butterfly post palatal seal preparation with 10 mm wide/4 mm deep box and four round holes, butterfly post palatal seal preparation with 20 mm wide/4 mm deep box, butterfly post dam preparation with 20 mm wide/4 mm deep box and four round holes, respectively. The boxes in the respective groups were prepared on the mid-heel area of the cast. The first group was included in the study as control. The initial master cast was indexed to standardize the measurement technique on all specimens before duplication. Maxillary denture tooth set-up was completed and indexed using laboratory putty to ensure a similar set-up on all specimens. Vertical and horizontal tooth positions were measured for the maxillary left central incisor, right and left first molars in waxed complete dentures, and following processing. The measurements were done using a digital vernier caliper with manufacturing accuracy of up to 0.01 mm. The study data were entered in a Microsoft Excel Spreadsheet. Statistical analysis was done using a paired Student t-test, ANOVA, and Tukey post hoc test set at 5% level of significance. RESULTS: The paired t-test (within groups) showed significant change in all linear tooth positions for groups 1 and 2. Groups 3 through 6 had significant change in vertical dimension only. One-way ANOVA indicated that no significant difference was seen in the vertical tooth movements between the groups; however, statistically significant reduction was seen in the horizontal tooth movements at the maxillary left central incisor, right and left first molars for groups 3 through 6 when compared to others without significant difference between them. CONCLUSIONS: Within the limitations of the study, it was concluded that the movement of the teeth horizontally could be reduced with master cast modification (box alone or box and round holes) whereas the vertical movement of the teeth was not affected by the cast modifications made across all groups.

In Vitro Assessment of the Abrasion Resistance of Two Types of Artificial Teeth Submitted to Brushing.

PURPOSE: To assess the effect of brushing with different solutions on the abrasion resistance of two types of acrylic resin teeth. MATERIALS AND METHODS: Maxillary premolars from two types of acrylic teeth (Biotone and Biotone IPN) were divided into six groups (n = 12), according to the solution used during brushing: distilled water (control), coconut soap, or dentifrice. A mechanical brushing machine was used to simulate approximately 1 year of brushing (11,000 strokes). The weight loss (WL) of teeth was obtained from the difference between the initial (IW) and final weight (FW) of each specimen, and the mean of percentage of weight loss (PWL) was calculated for each group. Data were analyzed using the Kruskal-Wallis test, followed by Bonferroni's post-test comparison (α = 0.05). RESULTS: A statistically significant difference was found for the factor solution (p < 0.001). Brushing using dentifrice caused the highest values of weight loss (-0.50%), in comparison with the groups brushed with coconut soap (0.00%) or distilled water (0.00%). CONCLUSIONS: For both types of artificial teeth, brushing with dentifrice produced higher abrasion than brushing with coconut soap or water.

Pre-clinical endodontic training with artificial instead of extracted human teeth: does the type of exercise have an influence on clinical endodontic outcomes?

AIM: To evaluate whether artificial resin teeth could replace extracted human teeth in pre-clinical endodontic training and if this teaching approach influences the outcome of root canal treatment on patients. METHODOLOGY: In a pre-clinical training course, students of group 1 (n = 44) performed simulated endodontic exercises on four plastic blocks and three extracted human teeth. Students of group 2 (n = 45) performed their exercises on plastic blocks and artificial resin teeth (Real-T Endo, Acadental, Lenexa, KS, USA). Both groups performed their first root canal treatments on patients in the following term. Radiographs taken during root canal treatment were used for the evaluation of treatment outcome. Distances between the master cone or the root filling and the radiographic apex as well as iatrogenic errors were assessed, and comparisons were made using Fischer's exact test. RESULTS: In the pre-clinical course root canal treatments performed by students of group 2 were more often classified as acceptable and a higher number of iatrogenic errors were observed in group 1. When root canal treatments were performed on patients for the first time, no significant difference was observed between the groups in terms of radiographic technical quality of root fillings. CONCLUSIONS: The application of artificial teeth instead of extracted human teeth had no effect on the technical quality of root fillings in terms of position in relation to the root apex or the creation of aberrations.

Levels of agreement between student and staff assessments of clinical skills in performing cavity preparation in artificial teeth.

OBJECTIVE: To determine the level of agreement between staff and students' assessment of clinical skills in performing tasks related to cavity preparation on a traditional dental manikin. METHODS: Two studies were conducted with two successive student cohorts: Study 1-138 year 1 BDS students in a 2009/10 cohort and Study 2-135 students in a 2010/11 cohort. Staff members and students rated the students' performance in preparing a cavity on a traditional dental manikin using artificial teeth: hand-held (Study 1) and located in a lower jaw (Study 2). A 5-item criterion-related scoring rubric was developed. The rubric assessed students' abilities to hold the instrument correctly, determine the angle of entry to the tooth, remove the caries, conserve healthy tissues and avoid pulp exposure. RESULTS: Agreement between the students' self-assessment and the staff's assessment was high for three of the five criteria (i.e. removal of artificial caries on the cavity wall, removal of artificial caries from the cavity floor and avoidance of pulp exposure). Levels of agreement for the remaining two criteria were moderate. A change in task difficulty affected the levels of agreement between staff and students, such that the more difficult the task, the greater the discrepancy in ratings. CONCLUSIONS: Students tend to overrate the quality of their performance when compared with staff ratings. Task difficulty has an impact on levels of agreement.