Evaluation of surface roughness of differently manufactured denture base materials.

STATEMENT OF PROBLEM: The popularity of computer-aided design and computer-aided manufacturing (CAD-CAM) dentures has led to the introduction of new denture materials and resins. However, studies on the surface characteristics of these materials and how they compare to dentures fabricated by more traditional methods are lacking. PURPOSE: The purpose of this cross-sectional study was to determine whether the surface roughness (Ra) of denture base materials differed based on manufacturing technique. MATERIAL AND METHODS: Disks of Ø10×2-mm (n=10) were fabricated using 6 different manufacturing techniques, including compression molding (Lucitone 199), injection molding (Ivocap High Impact), Computer Numerical Control (CNC) milling (Ivotion Base), and additive manufacturing on the Carbon M2 (Lucitone Digital Print), the SprintRay Pro55 S (Dentca Denture Base II), and the Envision One (Flexcera Base) systems. An automatic, noncontact laser confocal microscope (VK-X1000 Series; KEYENCE) was used to analyze the Ra surface roughness of each specimen at ×5 magnification. The images were imported into a multifile analyzer, horizontal and vertical roughness profiles were inserted into each scan, and Ra values were calculated and averaged by following the International Organization for Standardization (ISO) 4287 standard. A 1-way analysis of variance (ANOVA) was performed to compare the effect of manufacturing technique on surface roughness, followed by the Tukey multiple comparisons test (α=.05). RESULTS: The additively manufactured Dentca Denture Base II (AM-DB) exhibited a statistically significantly higher Ra when compared with the other test groups (P<.001). The additively manufactured Flexcera Base (AM-FB) showed a higher Ra mean value when compared with injection molding (IM) (P=.036). No statistically significant difference in surface roughness was found among the other tested materials representing the different processing methods (P>.05). CONCLUSIONS: The manufacturing method influences the Ra of denture base materials with varying results. The injection molding method resulted in the smoothest surface compared with additively manufactured and CNC-milled denture base materials.

Clinician perspectives on implementation of digitally fabricated complete dentures: A national survey of prosthodontists.

STATEMENT OF PROBLEM: Research on implementation factors for digitally fabricated complete dentures is sparse. PURPOSE: The purpose of this survey of prosthodontists was to explore the current usage of conventionally and digitally fabricated complete dentures and to identify factors that may impact their use. MATERIAL AND METHODS: A confidential cross-sectional survey consisting of 20 questions was conducted in 2019 using the Qualtrics Research Suite. The survey was distributed via electronic mail to all 1820 members of the American College of Prosthodontics. Frequency distributions, chi-squared tests, and Fisher exact tests were used to analyze the data and compare subgroups (α=.05). RESULTS: The response rate was 16.8% (N=305). A total of 31.5% of respondents were implementing digitally fabricated complete dentures, 36.6% were interested in learning and/or incorporating them, 37.7% reported that they had not tried them, and 12.7% had tried them but were not interested in using them again. When asked which factors were important when considering the implementation of digitally fabricated complete dentures, 55.8% indicated laboratory costs, 72.1% total chair time spent, and 81.9% patient satisfaction. Prosthodontists who graduated from dental school after about 1991 were more interested in learning about and incorporating digitally fabricated complete dentures than earlier graduates (P=.02). CONCLUSIONS: The survey results indicate that prosthodontists are implementing digitally fabricated complete dentures in clinical practice but not at the rate that might be expected of a technology that has been available for nearly a decade. Factors reported to matter in the decision to implement this technology were decreased time, overall cost, and improved patient satisfaction.

Time-lasting ceramic stains and glaze: A toothbrush simulation study.

OBJECTIVE: To evaluate and compare color stability and gloss retention of ceramic stains and glaze under simulated toothbrushing using dentifrices with different relative dentin abrasion (RDA). MATERIALS AND METHODS: Feldspathic porcelain, lithium disilicate, 3 mol% yttria partially stabilized zirconia, and 5 mol% yttria partially stabilized zirconia were evaluated. Ceramics were externally stained, glazed and mounted in the toothbrush simulator. A toothbrush with 300 g force was applied. Regular toothpaste (72 RDA) and charcoal toothpaste (RDA <200) were used. Linear brushing motion with cycle intervals: 5 k, 10 k, 30 k, and 50 k was achieved. Change in color (CIEΔE2000) and gloss measurements were collected using a reflection spectrophotometer (Ci 7600, X-rite) at baseline and cycle intervals. Repeated measures analysis of variance within specimen factors (ceramic type, toothpaste and cycles) was performed. RESULTS: ΔE00 was significantly different at 50 k cycles and with zirconia ceramics (P < .0001). Charcoal toothpaste was significantly different in ΔE00 compared to regular toothpaste (P > .0001). Loss of gloss was observed at 5 k and 30 k (charcoal and regular toothpaste respectively) regardless type of ceramic (P > .0001). CONCLUSION: Glass-phase ceramics retain stains longer than zirconia ceramics. Charcoal toothpaste affect color and gloss stability. Ceramic glaze maybe lost within the first 6 months in patients' mouth. CLINICAL SIGNIFICANCE: Long-term color and gloss stability of externally stained and glazed ceramics maybe a clinical concern. Charcoal toothpastes enhance loss of color and gloss of ceramic restorations.

The digitally replicated denture technique: A case report.

OBJECTIVE: Conventional complete denture protocols require several patient appointments with multiple laboratory procedures. There are multiple workflows incorporating digital technology that can expedite the process, whereas increasing predictability. The proposed digitally replicated denture technique (DRDT) demonstrates a predictable workflow for fabricating complete dentures for patients with existing dentures. CLINICAL PROCEDURE: A patient's existing maxillary and mandibular complete dentures were scanned with an intraoral scanner. The generated STL was then printed using a desktop 3D printer. This served as a custom tray and record base to decrease patient chair time and associated laboratory procedures. CONCLUSION: The DRDT workflow incorporates digital technology into a complete denture protocol to minimize laboratory steps and chair time when fabricating complete dentures for patients with existing prostheses. CLINICAL SIGNIFICANCE: The use of a digitally replicated denture using rapid prototyping can streamline the process of complete denture fabrication for patients with existing dentures.

Students' perception of digital waxing software for dental anatomy education.

The purpose of this study is to assess students' perception of digital waxing software for dental anatomy education. Dental students were introduced to digital waxing during a dental anatomy course, and were requested to finish a voluntary survey. Students strongly agreed (18.2%) or agreed (48.0%) with the statement "digital waxing contributed to my learning of dental anatomy", and strongly agreed (29.9%) and agreed (55.8%) with the statement "The digital waxing software helped develop my wax-up skills". The digital waxing software may be effective for dental anatomy education, but students do not believe digital waxing can be a replacement for conventional wax-up practice.