Automated facial landmark measurement using machine learning: A feasibility study

STATEMENT OF PROBLEM

Information regarding facial landmark measurement using machine learning (ML) techniques in prosthodontics is lacking.

PURPOSE

The objective of this study was to evaluate and compare the reliability, validity, and accuracy of facial anthropological measurements using both manual and ML landmark detection techniques.

MATERIAL AND METHODS

Two-dimensional (2D) frontal full-face photographs of 50 men and 50 women were made. The interpupillary width (IPW), interlateral canthus width (LCW), intermedial canthus width (MCW), interalar width (IAW), and intercommissural width (ICW) were measured on 2D digital images using manual and ML methods. The automated measurements were recorded using a programming language (Python), and a convolutional neural network (CNN) model was trained to detect human facial landmarks. The obtained data from the manual and ML methods were analyzed using intraclass correlation coefficients (ICCs), the paired sample t test, Bland-Altman plots, and the Pearson correlation analysis (α=.05).

RESULTS

Intrarater and interrater reliability values were greater than 0.90, indicating excellent reliability. The mean difference between the manual and ML measurements of IPW, MCW, IAW, and ICW was 0.02 mm, while it was 0.01 mm for LCW. No statistically significant differences were found between the measurements obtained by the manual and ML methods (P>.05). Highly significant positive correlations (P<.001) were obtained between the results of the manual and ML methods: (r=0.996[IPW], r=0.977[LCW], r=0.944[MCW], r=0.965[IAW], and r=0.997[ICW]).

CONCLUSIONS

In the field of prosthodontics, the use of ML methods provides a reliable alternative to manual digital techniques for carrying out facial anthropometric measurements.

Artificial Intelligence (AI)-driven dental education: Exploring the role of chatbots in a clinical learning environment

STATEMENT OF PROBLEM

Despite their widespread use in various educational contexts, the integration of chatbots into dental clinical education has not been thoroughly investigated. The noted discrepancy signifies a lack of understanding of how chatbots could enhance the personalized and interactive learning experiences of predoctoral dental students.

PURPOSE

The purpose of this study was to evaluate the awareness and perceptions of artificial intelligence (AI) technology, interaction experiences, and concerns about a custom-developed chatbot (CB) intervention in the clinical education of predoctoral dental students at the University of Illinois Chicago, College of Dentistry (UIC-COD) compared with the traditional Blackboard (BB) online platform.

MATERIAL AND METHODS

Eligible participants (n=86) providing verbal consent were allocated via the random block method into BB (n=43) and CB (n=43) groups and asked to engage with their designated platforms for 10 to 15 minutes by focusing on clinical inquiries in a predoctoral implant clinic and supported by a list of 35 typical questions. After the interaction, participants responded on a 5-point Likert scale to a 19-item survey probing AI awareness, platform engagement, and technological concerns. Survey data were anonymized and analyzed using descriptive, inferential statistics and nonparametric Mann-Whitney U tests to compare interventions. The Bonferroni correction for multiple comparisons was performed (α=.0045).

RESULTS

Neither the BB or CB group showed any difference in their awareness and perception of AI technology. The CB group demonstrated improved timeliness (P<.001), more interaction (P<.001), reduced faculty workload (P=.001), enhanced receptiveness (P=.002), and less anxiety (P<.001) and was more satisfied (P<.001) when compared with the BB group. However, concerns regarding the potential for incorrect information (P=.003) were more pronounced in the CB group.

CONCLUSIONS

The integration of chatbot technology into dental clinical education significantly enhanced learning and student engagement, highlighting the potential for future technological enrichment of the educational landscape.

Ozone therapy improves early stages of osseointegration in ovariectomized rats

OBJECTIVE

the aim of this study was to analyze the influence of ozone therapy (OZN) on peri-implant bone repair in critical bones by installing osseointegrated implants in the tibia of ovariectomized rats.

METHODOLOGY

ovariectomy was performed on 30 Wistar rats, aged six months (Rattus novergicus), and, after 90 days, osseointegrated implants were installed in each tibial metaphysis. The study groups were divided into the animals that received intraperitoneal ozone at a concentration of 700 mcg/kg - OZ Group (n=15) - and a control group that received an intraperitoneal saline solution and, for this reason, was named the SAL group (n=15). The applications for both groups occurred during the immediate post-operative period on the 2nd, 4th, 6th, 8th, 10th, and 12th day post-surgery. At various stages (14, 42, and 60 days), the animals were euthanized, and tests were performed on their tibiae. These tests include histomorphometric and immunohistochemical analyses, computerized microtomography, sampling in light-cured resin for calcified sections, and confocal microscopy. The obtained data were then analyzed using One-way ANOVA and the Shapiro-Wilk, Kruskal-Wallis, and student t-tests (P<0.05).

RESULTS

our findings indicate that the OZ group (3.26±0.20 mm) showed better cellular organization and bone neoformation at 14 days (SAL group, 0.90±1.42 mm) (P=0.001). Immunohistochemistry revealed that osteocalcin labeling was moderate in the OZ group and mild in the SAL group at 14 and 42 days post-surgery. The data from the analysis of calcified tissues (microtomography, histometric, and bone dynamism analysis) at 60 days showed no statistically significant differences between the groups (P=0.32).

CONCLUSION

it was concluded that ozone therapy anticipated the initial phases of the peri-implant bone repair process.

The effect of three dental cement types on the corrosion of dental implant surfaces

Statement of problem

One of the main challenges facing dental implant success is peri-implantitis. Recent evidence indicates that titanium (Ti) corrosion products and undetected-residual cement are potential risk factors for peri-implantitis. The literature on the impact of various types of dental cement on Ti corrosion is very limited.

Purpose

This study aimed to determine the influence of dental cement on Ti corrosion as a function of cement amount and type.

Materials and methods

Thirty commercially pure Ti grade 4 discs (19 × 7mm) were polished to mirror-shine (Ra ≈ 40 nm). Samples were divided into 10 groups (n = 3) as a cement type and amount function. The groups were no-cement as control, TempBond NE (TB3mm, TB5mm, and TB8mm), FujiCEM-II (FC3mm, FC5mm, and FC8mm), and Panavia-F-2.0 (PC3mm, PC5mm, and PC8mm). Tafel's method estimated corrosion rate (icorr) and corresponding potential (Ecorr) from potentiodynamic curves. Electrochemical Impedance Spectroscopy (EIS) data was utilized to obtain Nyquist and Bode plots. An equivalent electrical circuit estimated polarization resistance (Rp) and double-layer capacitance (Cdl). Inductively coupled plasma mass spectrometry (ICP-MS) analysis was conducted to analyze the electrolyte solution after corrosion. pH measurements of the electrolyte were recorded before and after corrosion tests. Finally, the corroded surface was characterized by a 3D white-light microscope and scanning electron microscope. Statistical analysis was conducted using either one-way ANOVA followed by Tukey's Post Hoc test or Kruskal-Wallis followed by Dunn's test based on data distribution.

Results

Based on cement amount, FC and PC significantly increased icorr in higher amounts (FC8mm-icorr = 8.22 × 10-8A/cm2, PC8mm-icorr = 5.61 × 10-8A/cm2) compared to control (3.35 × 10-8A/cm2). In contrast, TB3mm decreased icorr significantly compared to the control. As a function of cement type, FC increased icorr the most. EIS data agrees with these observations. Finally, corroded surfaces had higher surface roughness (Ra) compared to non-corroded surfaces.

Conclusion

The study indicated that cement types FC and PC led to increased Ti-corrosion as a function of a higher amount. Hence, the implant stability could be impacted by the selection, excessive cement, and a potentially increased risk of peri-implantitis.

Collagen membrane functionalized with magnesium oxide via room-temperature atomic layer deposition promotes osteopromotive and antimicrobial properties

Artificial bone grafting materials such as collagen are gaining interest due to the ease of production and implantation. However, collagen must be supplemented with additional coating materials for improved osteointegration. Here, we report room-temperature atomic layer deposition (ALD) of MgO, a novel method to coat collagen membranes with MgO. Characterization techniques such as X-ray photoelectron spectroscopy, Raman spectroscopy, and electron beam dispersion mapping confirm the chemical nature of the film. Scanning electron and atomic force microscopies show the surface topography and morphology of the collagen fibers were not altered during the ALD of MgO. Slow release of magnesium ions promotes bone growth, and we show the deposited MgO film leaches trace amounts of Mg when incubated in phosphate-buffered saline at 37 °C. The coated collagen membrane had a superhydrophilic surface immediately after the deposition of MgO. The film was not toxic to human cells and demonstrated antibacterial properties against bacterial biofilms. Furthermore, in vivo studies performed on calvaria rats showed MgO-coated membranes (200 and 500 ALD) elicit a higher inflammatory response, leading to an increase in angiogenesis and a greater bone formation, mainly for Col-MgO500, compared to uncoated collagen. Based on the characterization of the MgO film and in vitro and in vivo data, the MgO-coated collagen membranes are excellent candidates for guided bone regeneration.

Profile of prosthodontics program directors in North America

PURPOSE

To develop a current profile of prosthodontics program directors (PPDs) in United States dental schools and describe the current challenges and responsibilities of those serving in the position and assess the professional needs of the program directors (PDs) to better support them in their roles.

MATERIALS AND METHODS

A survey was sent to 51 participants who were identified as PPDs in North America via Qualtrics in 2019 to assess the professional needs of PDs to better support their roles. The survey consisted of 29 items organized into six sections: (1) demographic information; (2) hours and time spent in various areas of the job; (3) greatest challenges; (4) perceived importance of specific competencies; (5) opinions on the greatest rewards of the position; (6) their needs for support from the American College of Prosthodontists and advice for the future PD.

RESULTS

The response rate for this survey was 88.3%. Of the 45 respondents, the majority were white/non-Hispanic, followed by Asian/Pacific Islanders. The two largest and equal numbers of participants who worked for more than 10 years and between 1 and 3 years were observed with approximately 29% each, and PDs who worked less than a year occupied the least amount. Overall, 34% of PDs are on the tenure track and 80% of those are tenured. Teaching and clinical services took away the greatest time with approximately 42% and 22.1%, respectively. Thirty-five (78%) PDs listed the greatest challenge they encountered was the workload of the role. Skills listed in leadership and personnel competencies were all rated more important than most of the skills listed in management.

CONCLUSIONS

There is a wide gender gap and a lack of racial diversity among the PPDs. The biggest challenge faced by them is the amount of workload followed by budget and fiscal constraints. And for their improved efficiency, they gave emphasis on learning time management and continuous clinical training of newer advances.

Predictability of single versus double-barrel vascularized fibula flaps and dental implants in mandibular reconstructions: A systematic review and meta-analysis of prospective studies

STATEMENT OF PROBLEM

Patients with vascularized bone flaps from the fibula have reduced bone height, in which case a higher prosthetic abutment is needed for their implant-supported prosthesis. Although the double-flap technique seems promising, systematic reviews and meta-analyses of prospective studies are lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate the grafted areas of single barrel fibular flaps (SBFF) and double-barrel fibular flaps (DBFF) by considering failure rates, dental implant complications, and bone union at the osteotomy sites.

MATERIAL AND METHODS

A systematic review and meta-analysis was performed in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement, population, intervention, control, and outcomes (PICO) question, and the National Health and Medical Research Council scales. The event rate of complications and failures was calculated with a confidence interval (CI) of 95%.

RESULTS

A total of 13 prospective studies with 441 participants and 330 graft sites were identified. A total of 235 participants had SBFF with 445 implants, and 95 had DBFF with 164 implants. The overall combined graft failure rates were 4.2% for SBFF and 3.2% for DBFF. The complication rate was 10% for SBFF and 1.9% for DBFF. Implant failure was at 4.7% in the SBFF group and 3.4% in the DBFF group.

CONCLUSIONS

Complication rates and implant failures were similar for SBFF and DBFF. Therefore, for long-term oral rehabilitation, both SBFF and DBFF are suitable procedures for mandibular reconstruction.

Machine learning model to predict the width of maxillary central incisor from anthropological measurements

PURPOSE

To improve smile esthetics, clinicians should comprehensively analyze the face and ensure that the sizes selected for the maxillary anterior teeth are compatible with the available anthropological measurements. The inter commissural (ICW), interalar (IAW), intermedial-canthus (MCW), interlateral-canthus (LCW), and interpupillary (IPW) widths are used to determine the width of maxillary central incisors (CW). The aim of this study was to develop an automated approach using machine learning (ML) algorithms to predict central incisor width in a young Turkish population using anthropological measurements. This automation can contribute to digital dentistry and clinical decision-making.

METHODS

In the initial phase of this cross-sectional study, several ML regression models-including multiple linear regression (MLR), multi-layer-perceptron (MLP), decision-tree (DT), and random forest (RF) models-were validated to confirm the central width prediction accuracy. Datasets containing only male and female measurements, as well as combined were considered for ML model implementation, and the performance of each model was evaluated for an unbiased population dataset.

RESULTS

Compared with the other algorithms, the RF algorithm showed improved performance for all cases, with an accuracy of 96%, which represents the percentage of correct predictions. The plot reveals the applicability of the RF model in predicting the CW from anthropological measurements irrespective of the candidate's sex.

CONCLUSIONS

These results demonstrated the possibility of predicting central incisor widths based on anthropometric measurements using ML models. The accurate central incisor width prediction from these trials also indicates the applicability of the proposed model to be deployed for enhanced clinical decision-making.

Unpredictable Electrochemical Processes in Ti Dental Implants: The Role of Ti Ions and Inflammatory Products

Peri-implantitis is a substantially prevailing condition. A potential risk factor for peri-implantitis is Ti implant corrosion. During inflammation, substantial quantities of reactive oxygen species (ROS) secretion and local acidification occur. Little is known about the interaction between the inflammatory and corrosion products on Ti surface corrosion. Therefore, the objective of the current study was to evaluate the synergistic effect of hydrogen peroxide (H2O2), lactic acid, and Ti ions on Ti corrosion. Twenty-seven commercially pure Ti samples were polished (Ra ≈ 45 nm) and divided into 9 groups as a function of electrolyte: (1) artificial saliva (AS) as control (C), (2) AS + Ti ions 20 ppm (Ti), (3) AS + lactic acid (pH = 5.5) (L), (4) AS + lactic acid + Ti ions 20 ppm (TiL), (5) AS + H2O2 0.5 mM (HP0.5), (6) AS + H2O2 1.0 mM (HP1.0), (7) AS + H2O2 0.5 mM + Ti ions 20 ppm (HP0.5Ti), (8) AS + H2O2 0.5 mM + lactic acid (HP0.5L), and (9) AS + H2O2 0.5 mM + Ti ions 20 ppm + lactic acid (HP0.5TiL). Electrochemical tests were performed following ASMT guidelines. Based on Tafel's method, current density (icorr) and corresponding potential (Ecorr) were acquired from potentiodynamic curves. Using electrochemical intensity spectroscopy (EIS), Nyquist and Bode plots were derived. Using a modified Randles circuit, charge transfer resistance (Rct) and capacitance (Cdl) were estimated. Based on open-circuit potential data, groups C and Ti had the lowest potentials (around -0.3 and -0.4 V vs SCE, respectively), indicating a lower passivation tendency compared to the other groups. From potentiodynamic curves, groups HP0.5 and HP1.0 increased icorr the most. From EIS data, groups HP0.5 and HP1.0 demonstrated the lowest impedance and phase angle on the Bode plot, indicating the highest corrosion kinetics. Based on EIS modeling, the combination of Ti ions, lactic acid, and H2O2 (group HP0.5TiL) significantly decreased Rct (p < 0.05). In conclusion, the concurrent presence of Ti ions, lactic acid, and H2O2 in the vicinity of the Ti surface increased the corrosion kinetics. High corrosion may produce more Ti products in the peri-implant tissues, which may increase the potential risk of peri-implantitis.

Evaluating augmented reality e-typodont to improve a patient's dental implant health literacy

STATEMENT OF PROBLEM

Information regarding dental implants can be difficult to understand for participants. Improving patients' dental implant health literacy remains a challenging process.

PURPOSE

The purpose of this clinical study was to develop and evaluate patients' understanding of the implant treatment procedure, components, and sequences using traditional typodont and augmented reality (AR) applications (e-typodont), with the goal of improving their oral health literacy.

MATERIAL AND METHODS

Participants who had sought dental implant treatment at the group practice and implant clinic at the University of Illinois Chicago (UIC) College of Dentistry were invited to enroll in this study. Participants were asked to fill out the first questionnaire (Q1) assessing their understanding of implant treatment procedures, components, and sequences. The participants were randomly exposed to 1 of the 2 modes of delivering education, typodont or AR e-typodont. The participants were asked to complete the additional 2 questionnaires (Q2 and Q3), and the posttest questionnaire (Q1) to re-evaluate their understanding of the implant treatment procedure, components, and sequences. All data were entered and coded into a spreadsheet. Descriptive (mean) and statistical (Wilcoxon Signed Ranks and Mann-Whitney U test) analyses were used (α=.05).

RESULTS

Both interventions significantly increased participants' understanding of implant treatments (typodont: P=.004; e-typodont: P<.001), implant components (typodont: P=.003; e-typodont: P<.001), and implant treatment sequences (typodont: P=.001; e-typodont: P<.001). The e-typodont group significantly improved participants' understanding of implant treatments (P=.006), implant components (P=.023), and implant treatment sequences (P=.008) compared with the typodont group. Participants perceived the e-typodont mode of delivery to be significantly more interesting (P=.002), interactive (P=.008), educational (P=.002), user-friendly (P=.016), and "Wow" (P=.002) compared with the traditional typodont mode of delivery.

CONCLUSIONS

Both interventions improved participants' understanding of implant treatment procedures, components, and sequences. The e-typodont showed better improvement in participants' understanding of dental implants compared with the traditional typodont.

Early Predicting Tribocorrosion Rate of Dental Implant Titanium Materials Using Random Forest Machine Learning Models

Early detection and prediction of bio-tribocorrosion can avert unexpected damage that may lead to secondary revision surgery and associated risks of implantable devices. Therefore, this study sought to develop a state-of-the-art prediction technique leveraging machine learning(ML) models to classify and predict the possibility of mechanical degradation in dental implant materials. Key features considered in the study involving pure titanium and titanium-zirconium (zirconium = 5, 10, and 15 in wt%) alloys include corrosion potential, acoustic emission(AE) absolute energy, hardness, and weight-loss estimates. ML prototype models deployed confirms its suitability in tribocorrosion prediction with an accuracy above 90%. Proposed system can evolve as a continuous structural-health monitoring as well as a reliable predictive modeling technique for dental implant monitoring.

Feasible low bone density condition for assessing bioactivity in ex-in vivo and in vivo studies

OBJECTIVE

To choose a critical animal model for assessments of bone repair with implant installation by comparing senile rats (SENIL) to young ovariectomized rats (OXV).

METHODOLOGY

For the ex-in vivo study, the femurs were precursors for bone marrow mesenchymal stem cells. Cellular responses were performed, including cell viability, gene expression of osteoblastic markers, bone sialoprotein immunolocalization, alkaline phosphatase activity, and mineralized matrix formation. For the in vivo study, the animals received implants in the region of the bilateral tibial metaphysis for histometric, microtomography, reverse torque, and confocal microscopy.

RESULTS

Cell viability showed that the SENIL group had lower growth than OVX. Gene expression showed more critical responses for the SENIL group (p<0.05). The alkaline phosphatase activity obtained a lower expression in the SENIL group, as for the mineralization nodules (p<0.05). The in vivo histological parameters and biomechanical analysis showed lower data for the SENIL group. The confocal microscopy indicated the presence of a fragile bone in the SENIL group. The microtomography was similar between the groups. The histometry of the SENIL group showed the lowest values (p<0.05).

CONCLUSION

In experimental studies with assessments of bone repair using implant installation, the senile model promotes the most critical bone condition, allowing a better investigation of the properties of biomaterials and topographic changes.

Bioactive Carbonate Apatite Cement with Enhanced Compressive Strength via Incorporation of Silica Calcium Phosphate Composites and Calcium Hydroxide

Carbonate apatite (CO₃Ap) is a bioceramic material with excellent properties for bone and dentin regeneration. To enhance its mechanical strength and bioactivity, silica calcium phosphate composites (Si-CaP) and calcium hydroxide (Ca(OH)₂) were added to CO₃Ap cement. The aim of this study was to investigate the effect of Si-CaP and Ca(OH)₂ on the mechanical properties in terms of the compressive strength and biological characteristics of CO₃Ap cement, specifically the formation of an apatite layer and the exchange of Ca, P, and Si elements. Five groups were prepared by mixing CO₃Ap powder consisting of dicalcium phosphate anhydrous and vaterite powder added by varying ratios of Si-CaP and Ca(OH)₂ and 0.2 mol/L Na₂HPO₄ as a liquid. All groups underwent compressive strength testing, and the group with the highest strength was evaluated for bioactivity by soaking it in simulated body fluid (SBF) for one, seven, 14, and 21 days. The group that added 3% Si-CaP and 7% Ca(OH)₂ had the highest compressive strength among the groups. SEM analysis revealed the formation of needle-like apatite crystals from the first day of SBF soaking, and EDS analysis indicated an increase in Ca, P, and Si elements. XRD and FTIR analyses confirmed the presence of apatite. This combination of additives improved the compressive strength and showed the good bioactivity performance of CO₃Ap cement, making it a potential biomaterial for bone and dental engineering applications.

Analysis of clinical parameter and tumor necrosis factor-alpha levels on keratinized tissue around implant and tooth

Background

Studies have shown the importance of keratinized tissue around implants to prevent peri-implant diseases. This study aims to analyze the correlation of keratinized tissue around implants and teeth with clinical parameter scores and tumor necrosis factor-alpha (TNF-α) levels.

Materials and Methods

A cross-sectional study of 20 adults with 20 dental implants and 20 contralateral teeth that have functioned suprastructurally for more than 3 months without any systemic diseases. Keratinized tissue around implant and tooth was measured. The clinical examinations included the plaque index (PI), papilla bleeding index (PBI), and pocket depth (PD). Peri-implant sulcus fluid (PISF) and gingival crevicular fluid were collected to measure TNF-α levels. Spearman's test was used to analyze the correlation.

Results

Significant differences were found between keratinized tissue around the implant in PI, PBI, and PD (P < 0.05). Differences were found between wide and narrow keratinized tissue around contralateral teeth in PI and PBI (P < 0.05) but not in PD. TNF-α levels were not correlate to keratinized tissue width around implant and contralateral tooth (P > 0.05). Strong correlations were found between each clinical parameter score and the keratinized tissue width of peri-implant tissue in PI, PBI, and PD.

Conclusion

The clinical parameter score between wide and narrow keratinized tissue around implant showed strong correlation, particularly in PBI. This shows the importance of adequate keratinized tissue around implant to maintain implant stability.

Collagen Membranes Functionalized with 150 Cycles of Atomic Layer Deposited Titania Improve Osteopromotive Property in Critical-Size Defects Created on Rat Calvaria

The membranes used in bone reconstructions have been the object of investigation in the field of tissue engineering, seeking to improve their mechanical strength and add other properties, mainly the osteopromotive. This study aimed to evaluate the functionalization of collagen membranes, with atomic layer deposition of TiO2 on the bone repair of critical defects in rat calvaria and subcutaneous biocompatibility. A total of 39 male rats were randomized into four groups: blood clot (BC), collagen membrane (COL), COL 150—150 cycles of titania, and COL 600—600 cycles of titania. The defects were created in each calvaria (5 mm in diameter) and covered according to each group; the animals were euthanized at 7, 14, and 28 days. The collected samples were assessed by histometric (newly bone formed, soft tissue area, membrane area, and residual linear defect) and histologic (inflammatory cells and blood cells count) analysis. All data were subjected to statistical analysis (p < 0.05). The COL150 group showed statistically significant differences compared to the other groups, mainly in the analysis of residual linear defects (1.5 ± 0.5 × 106 pixels/µm2 for COL 150, and around 1 ± 0.5 × 106 pixels/µm2 for the other groups) and newly formed bone (1500 ± 1200 pixels/µm for COL 150, and around 4000 pixels/µm for the others) (p < 0.05), demonstrating a better biological behavior in the chronology of defects repair. It is concluded that the collagen membrane functionalized by TiO2 over 150 cycles showed better bioactive potential in treating critical size defects in the rats’ calvaria.

Level of evidence and characteristics of clinical studies published in leading prosthodontics journals

STATEMENT OF PROBLEM

Data on the level of evidence and the characteristics of studies published in peer-reviewed prosthodontic journals are lacking.

PURPOSE

The purpose of this study was to investigate the characteristics and level of evidence (LOE) scores of studies published in 3 leading peer-reviewed prosthodontic journals.

MATERIAL AND METHODS

Clinical studies published in the Journal of Prosthetic Dentistry (JPD), the Journal of Prosthodontics (JP), and the International Journal of Prosthodontics (IJP) in 2013 and 2020 were included in the analysis. Abstracts, letters to the editor, book reviews, and animal and laboratory studies were excluded from the investigation. For each study, design, type and LOE scores (Levels 1 to 5), publication year, impact factor (IF) of the journals, geographic origins of the first and corresponding authors, and funding status were recorded. Level 1 and Level 2 were defined as high evidence (HE), and Level 3, Level 4, and Level 5 were defined as low evidence (LE). Descriptive statistics and logistic regression analysis were performed (α=.05).

RESULTS

Among the 439 studies included in the analysis, the proportion of HE and LE studies was 14.1% and 85.9%, respectively. According to univariate and multivariate analysis results, year of publication (P=.010 and P=.029), geographic origin of the corresponding author (P<.001), and funding status (P<.001 and P=.002) were significantly associated with the LOE of a study. However, the journal IF was not associated with LOE (P=.328).

CONCLUSIONS

Although the number of HE studies in 3 leading prosthodontic journals has increased over time, the total number was still limited compared with LE studies. A further improvement in the overall LOE of clinical studies in prosthodontics is needed.

The race for the optimal antimicrobial surface: perspectives and challenges related to plasma electrolytic oxidation coating for titanium-based implants

Plasma electrolytic oxidation (PEO) is a low-cost, structurally reliable, and environmentally friendly surface modification method for orthopedic and dental implants. This technique is successful for the formation of porous, corrosion-resistant, and bioactive coatings, besides introducing antimicrobial compounds easily. Given the increase in implant-related infections, antimicrobial PEO-treated surfaces have been widely proposed to surmount this public health concern. This review comprehensively discusses antimicrobial implant surfaces currently produced by PEO in terms of their in vitro and in vivo microbiological and biological properties. We present a critical [part I] and evidence-based [part II] review about the plethora of antimicrobial PEO-treated surfaces. The mechanism of microbial accumulation on implanted devices and the principles of PEO technology to ensure antimicrobial functionalization by one- or multi-step processes are outlined. Our systematic literature search showed that particular focus has been placed on the metallic and semi-metallic elements incorporated into PEO surfaces to facilitate antimicrobial properties, which are often dose-dependent, without leading to cytotoxicity in vitro. Meanwhile, there are concerns over the biocompatibility of PEO and its long-term antimicrobial effects in animal models. We clearly highlight the importance of using clinically relevant infection models and in vivo long-term assessments to guarantee the rational design of antimicrobial PEO-treated surfaces to identify the 'finish line' in the race for antimicrobial implant surfaces.

Effect of Nano Ceramic Coating on Color Perceptibility and Acceptability of Polymethylmethacrylate: In Vitro and Clinical Study

The effect of a novel nano-ceramic coating (TiO₂) using an atomic layer deposition (ALD) technique on the surface of polymethyl methacrylate (PMMA) material was investigated. The patients' and clinicians' perception and acceptance of the PMMA color with TiO₂ coating were also examined. In vitro color measurement was performed on thirty specimens (light, original, and dark pink) before and after TiO₂ coating. Patients' and clinicians' perception and acceptance of color changes on PMMA were measured and compared. Descriptive and analytic statistics were analyzed (a = 0.05). TiO₂ films were successfully deposited on the PMMA specimen by the ALD technique. Color changes after TiO₂ coating were observed on all three PMMA shades, significantly higher than the established 50:50% perceptibility threshold, but below the established 50:50% acceptability threshold. The percentage of patients that perceived a color difference after TiO₂ coating were 83.3%, 63.9%, and 77.8% for light, original, and dark pink, respectively. The percentages of clinicians that were satisfied with the color difference were 96.4%, 80%, and 69.2% for light, original, and dark pink, respectively. Color changes after TiO₂ coating were observed, but below the acceptable threshold. The clinical survey demonstrated that a color difference was perceived but was clinically acceptable. In general, laypeople have lower perception and higher acceptance of changes in PMMA color than clinicians.

The Effect of Smoking and Brushing on the Color Stability and Stainability of Different CAD/CAM Restorative Materials

This study aimed to investigate and compare the color stability and stainability of computer-aided design/computer-aided manufacturing (CAD/CAM) restorative materials in their glazed (G) and polished (P) state when exposed to cigarette smoke, as well as after brushing. Three CAD/CAM restorative materials were investigated: lithium disilicate CAD (LD), zirconia (Zr), and Telio PMMA CAD (PMMA), according to their surface finishing and assignment to cigarette smoking exposure or soaking in the saliva (control) group. The color change (∆E) was calculated before and after the intervention performed for all specimens, using the L*a*b values to quantitatively assess the shade differences. Statistical analysis was performed using one-way repeated measures ANOVA and Bonferroni multiple comparison analysis (α = 0.05). The surface finishing did not influence the materials’ stainability. Color change was noted after smoking, LD and Zr-G and Zr-P had a comparable color change (p > 0.05), while PMMA presented lower ∆E values (p < 0.05). After brushing, all specimens had a significant color change that was high for LD-G and LD-P, and Zr-G, compared with Zr-P and PMMA (p < 0.05). In conclusion, the exposure to cigarette smoke showed that LD, Zr, and PMMA are all susceptible to staining, but brushing decreases surface staining.

Attachment systems for mandibular implant-supported overdentures: A systematic review and meta-analysis of randomized controlled trials

STATEMENT OF PROBLEM

Although mandibular implant-supported overdentures have been highly recommended as a treatment option, a consensus on the type of attachment systems that can be used to increase implant and prostheses survivability is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to compare different types of attachments for retention by investigating outcome measures such as implant and prosthesis survival rates and biological and prosthesis complications in participants with a mandibular implant-supported overdenture.

MATERIAL AND METHODS

The search was performed in the PubMed, Cochrane, Embase, and Scopus databases by following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria and registered with the International Prospective Register of Systematic Reviews (CRD42021253566). An analysis of association was conducted between different attachment systems and implant and overdenture survival rates in randomized controlled clinical trials.

RESULTS

The initial search indicated 477 studies, of which 25 randomized controlled trials (RCTs) were included for analysis. A total of 2154 implants and 737 overdentures were analyzed in the meta-analysis. The main results indicated the failure rate for dental implants to be 2.0% (95% confidence interval [CI], 1.3 to 3.2) and overdentures 4.2% (95% CI, 1.6 to 10.5), respectively. With regard to different attachment systems, a similar failure rate was identified with bar-type retention (7.7% to 95% CI, 3.0 to 18.1), magnetic retention systems (7.6% to 95% CI, 2.2 to 22.7), and ball-type retention (6.8% to 95% CI, 3.0 to 14.3). No significant difference was found in biological complications for splinted and unsplinted implant overdentures (P=.902). Regarding prosthetic complications, the most favorable groups were LOCATOR attachments followed by telescopic and Conus, bar, and ball attachments. Magnet attachments had higher prosthetic complications (7.4 times) than the other attachments.

CONCLUSIONS

Implants and implant-supported mandibular overdentures showed a high survival rate irrespective of the attachment system used. Splinting implants did not significantly affect the rate of biological complications. Prosthetic complications were most common for magnet and least common for LOCATOR attachments.

Is atomic layer deposition of silver possible on N95 masks?

Due to the COVID19 outbreak, there has been increasing interest in tailoring, modifying and improving conventional personal protective equipment to increase their service life and make them more effective against viruses and bacteria. Here, atomic layer deposition (ALD) was used to functionalize the filter of N95 mask with nano-islands of silver. X-ray photoelectron spectroscopy and x-ray absorption fine structure were used for ALD silver characterization; microbiological assay was conducted to study the effectiveness of the deposited silver against the air-borne pathogen Staphylococcus aureus (S. aureus). Results showed that silver ALD successfully functionalized the N95 mask at 90 and 120 °C for two different numbers of ALD cycles (1100 and 1500 cycles). The deposited silver nano-islands were stable on the N95 filter media against washing. The leaching of silver nano-islands was studied using inductively coupled plasma mass spectrometry of phosphate-buffered saline solution after soaking the mask in it over predetermined times. <9% of Ag was removed after a maximum time of 4 h that was investigated. Antimicrobial tests showed that for samples functionalized with 1100 ALD cycles of Ag, 76% reduction in S. aureus colony-forming units content was observed after 24 h of biofilm development on the mask surfaces.

Impact of COVID-19 on Malaysian dental students' physical, mental, financial and academic concerns

Background

The coronavirus disease 2019 (COVID-19) caused by a novel coronavirus (SARS-CoV-2) has gained worldwide attention and proved to hold an impact to humankind in all aspects of life. Dental students’ performances may indirectly be affected following the preventive measures in containing the disease. This study aims to evaluate the impact of COVID-19 pandemic on physical, mental, financial health and academic concern among dental students in Malaysia.

Methods

The current research implemented a cross sectional study among dental students in Malaysia. Assessment of the impact of COVID-19 on dental education was done by the distribution of a set of online survey consisting of 28 questions to dental students (n = 353) from public and private universities in Malaysia. The questionnaires include sociodemographic backgrounds and assessment on the mental health, financial health, physical health and academic concern. Kruskal Wallis test and Mann–Whitney U test were used to analyse the impact of COVID-19 to these 4 domains according to sociodemographic background.

Results

A total number of 353 respondents was recorded and 76.2% comprised of female. 59.7% were clinical students and 40.3% were preclinical students. Most of students were concerned about their own emotional health, financial concern, physical wellbeing, in which Year 3 students were found to be more concerned about their mental and financial health concern.

Conclusions

COVID-19 pandemic had indeed significantly affected Malaysian dental students mainly due to fear of the quality of online learning and the amount of clinical skills acquired. Therefore, it is important to identify dental stressors and lessen the impact of COVID-19 to dental students.

Knowledge, Perceived Risk, and Preventive Behaviors amidst Covid-19 Pandemic among Dental Students in Malaysia

PURPOSE

Coronavirus disease 19 (COVID-19) has affected dental education in Malaysia. However, studies on dental students' knowledge, perception, and behaviors with regards to COVID-19 are very limited. Thus, this study aims to determine the knowledge status, perceived risk, and preventive behaviors of dental students in Malaysia regarding COVID-19.

METHODS

A cross-sectional study was conducted among students from 13 dental schools across Malaysia using online questionnaires.

RESULTS

From 355 respondents, 93.5% obtained a high score of knowledge of COVID-19. Female respondents scored higher than males in perceived risks and preventive behaviors. Chinese respondents scored highest in knowledge, while Malay respondents had the highest perceived risk score. The mean preventive behavior score did not vary across ethnicity. On-campus students scored higher in knowledge and perceived risk whereas off-campus students practiced more preventive behaviors. Clinical students' knowledge score was higher than preclinical students. Final year students scored higher in knowledge and perceived risk compared to their juniors.

CONCLUSION

The majority of dental students have good knowledge and a high perceived risk of COVID-19, and they practiced most of the preventive behaviors. However, the latest information on this disease should be incorporated into dental schools' curriculums and updated periodically.

Ti-Ions and/or Particles in Saliva Potentially Aggravate Dental Implant Corrosion

The corrosive titanium products in peri-implant tissues are a potential risk factor for peri-implantitis. There is very limited information available on the effect of the corrosion and wear products on the dental implant corrosion. Therefore, we determined the influence of Ti-ions and Ti-particles on Ti corrosion. Eighteen commercially pure-Ti-grade-2 discs were polished to mirror-shine. Samples were divided into six groups (n = 3) as a function of electrolytes; (A) Artificial saliva (AS), (B) AS with Ti-ions (the electrolyte from group A, after corrosion), (C) AS with Ti-particles 10 ppm (D) AS with Ti-particles 20 ppm, (E) AS with Ti-ions 10 ppm, and (F) AS with Ti-ions 20 ppm. Using Tafel’s method, corrosion potential (E_corr) and current density (I_corr) were estimated from potentiodynamic curves. Electrochemical Impedance Spectroscopy (EIS) data were used to construct Nyquist and Bode plots, and an equivalent electrical circuit was used to assess the corrosion kinetics. The corroded surfaces were examined through a 3D-white-light microscope and scanning electronic microscopy. The data demonstrated that the concentration of Ti-ions and corrosion rate (I_corr) are strongly correlated (r = 0.997, p = 0.046). This study indicated that high Ti-ion concentration potentially aggravates corrosion. Under such a severe corrosion environment, there is a potential risk of increased implant associated adverse tissue reactions.

Prediction of tribocorrosion processes in titanium-based dental implants using acoustic emission technique: Initial outcome

The use of dental implants is growing rapidly for the last few decades and Ti-based dental implants are a commonly used prosthetic structure in dentistry. Recently, the combined effect of corrosion and wear, called tribocorrosion, is considered as a major driving process in the early failure of dental implants. However, no previous study has reported the prediction of tribocorrosion processes in advance. Therefore, this study is a novel investigation on how the acoustic emission (AE) technique can predict tribocorrosion processes in commercially-pure titanium (cpTi) and titanium-zirconium (TiZr) alloys. In this study, tribocorrosion tests were performed under potentiostatic conditions and AE detection system associated with it captures AE data. Current evolution and friction coefficient data obtained from the potentiostatic evaluations were compared with AE absolute energy showcased the same data interpretation of tribocorrosion characteristics. Other AE data such as duration, count, and amplitude, matched more closely with other potentiostatic corrosion evaluations and delivered more promising results in the detection of tribocorrosion. Hence, AE can be consider as a tool for predicting tribocorrosion in dental implants. Experimental results also reveal Ti5Zr as one of the most appropriate dental implant materials while exposing Ti10Zr's lower effectiveness to withstand in the simulated oral environment.

Atomic layer deposition on dental materials: Processing conditions and surface functionalization to improve physical, chemical, and clinical properties - A review

Surface functionalization is an effective approach to improve and enhance the properties of dental materials. A review of atomic layer deposition (ALD) in the field of dental materials is presented. ALD is a well-established thin film deposition technique. It is being used for surface functionalization in different technologies and biological related applications. With film thickness control down to Ångström length scale and uniform conformal thin films even on complex 3D substrates, high quality thin films and their reproducibility are noteworthy advantages of ALD over other thin film deposition methods. Low temperature ALD allows temperature sensitive substrates to be functionalized with high quality ultra-thin films too. In the current work, ALD is elaborated as a promising method for surface modification of dental materials. Different aspects of conventional dental materials that can be enhanced using ALD are discussed. Also, the influence of different ALD thin films and their microstructure on the surface properties, corrosion-resistance, antibacterial activity, biofilm formation, and osteoblast compatibility are addressed. Depending on the stage of advancement for the studied materials reported in the literature, these studies are then categorized into four stages: fabrication & characterization, in vitro studies, in vivo studies, and human tests. Materials coated with ALD thin films with potential dental applications are also presented here and they are categorized as stage 1. The purpose of this review is to organize and present the up to date ALD research on dental materials. The current study can serve as a guide for future work on using ALD for surface functionalization and resulting property tuning of materials in real world dental applications.

Revealing nanoscale mineralization pathways of hydroxyapatite using in situ liquid cell transmission electron microscopy

To treat impairments in hard tissues or overcome pathological calcification in soft tissues, a detailed understanding of mineralization pathways of calcium phosphate materials is needed. Here, we report a detailed mechanistic study of hydroxyapatite (HA) mineralization pathways in an artificial saliva solution via in situ liquid cell transmission electron microscopy (TEM). It is found that the mineralization of HA starts by forming ion-rich and ion-poor solutions in the saliva solution, followed by coexistence of the classical and nonclassical nucleation processes. For the nonclassical path, amorphous calcium phosphate (ACP) functions as the substrate for HA nucleation on the ACP surface, while the classical path features direct HA nucleation from the solution. The growth of HA crystals on the surface of ACP is accompanied by the ACP dissolution process. The discoveries reported in this work are important to understand the physiological and pathological formation of HA minerals, as well as to engineer the biomineralization process for bone healing and hard tissue repairs.

Highly Conductive Collagen by Low-Temperature Atomic Layer Deposition of Platinum

In modern biomaterial-based electronics, conductive and flexible biomaterials are gaining increasing attention for their wide range of applications in biomedical and wearable electronics industries. The ecofriendly, biodegradable, and self-resorbable nature of these materials makes them an excellent choice in fabricating green and transient electronics. Surface functionalization of these biomaterials is required to cater to the need of designing electronics based on these substrate materials. In this work, a low-temperature atomic layer deposition (ALD) process of platinum (Pt) is presented to deposit a conductive thin film on collagen biomaterials, for the first time. Surface characterization revealed that a very thin ALD-deposited seed layer of TiO₂ on the collagen surface prior to Pt deposition is an alternative for achieving a better nucleation and 100% surface coverage of ultrathin Pt on collagen surfaces. The presence of a pure metallic Pt thin film was confirmed from surface chemical characterization. Electrical characterization proved the existence of a continuous and conductive Pt thin film (∼27.8 ± 1.4 nm) on collagen with a resistivity of 295 ± 30 μΩ cm, which occurred because of the virtue of TiO₂. Analysis of its electronic structures showed that the presence of metastable state due to the presence of TiO₂ enables electrons to easily flow from valence into conductive bands. As a result, this turned collagen into a flexible conductive biomaterial.

Three-Dimensional Accuracy of Conventional Versus Digital Complete Arch Implant Impressions

PURPOSE

The accuracy of digital impressions is still controversial for complete arch implant cases. The aim of this study is to compare the accuracy of different intraoral scanners with the conventional technique in terms of trueness and precision in a complete arch implant model.

MATERIAL AND METHODS

Eight implants were inserted asymmetrically in a polyurethane edentulous mandibular model with different angulations. A 3-dimensional (3D) reference model was obtained by scanning this polyurethane model with an optical scanner. First, digital impressions were made by using 3 different intraoral scanners: Carestream 3500 (DC), Cerec Omnicam (DO) and 3Shape Trios 3 (DT). Subsequently, a nonsplinted open tray impression technique was used for conventional impression group (C) and then the master casts were digitalized with a lab scanner. Each 10 STL files belonging to 4 different impression groups were imported to a reverse engineering program, to measure distance and angle deviations from the reference model. All statistical analyses were performed after taking absolute values of the data. After comparing the impression groups with one-way ANOVA, the trueness and precision values were analyzed by Tukey post hoc test and 0.05 was used as the level of significance.

RESULTS

The mean trueness of distance was 123.06 ± 89.83 µm for DC, 229.72 ± 121.34 µm for DO, 209.75 ± 47.07 µm for DT, and 345.32 ± 75.12 µm for C group (p < 0.0001). While DC showed significantly lower deviation compared to DO and C, no significant difference was found between DC and DT. C showed the highest distance deviation significantly in all groups; and no significant difference was found between DO and DT groups. In angle measurements; the trueness was 0.26° ± 0.07° for DC, 0.53° ± 0.42° for DO, 0.33° ± 0.30° for DT, and 0.74° ± 0.65° for C group. There was no significant difference between the groups in terms of angular trueness (p = 0.074). In terms of the precision for distance, the results of DC 80.43 ± 29.69 µm, DO 94.06 ± 69.96 µm, DT 35.55 ± 28.46 µm and C 66.97 ± 36.69 µm were determined (p = 0.036). The significant difference was found only between DT and DO among all groups. Finally, angular precision was determined to be 0.19° ± 0.11° for DC, 0.30° ± 0.28° for DO, 0.22° ± 0.19° for DT, and 0.50° ± 0.38° for Group C. No significant difference was found between the groups, in terms of angular precision (p = 0.053).

CONCLUSIONS

All digital impression groups yielded superior data compared to conventional technique in terms of trueness. DC formed the impression group with the highest trueness in both distance and angular measurements. The results of this in vitro study suggest the use of intraoral scanners compared to the conventional impression techniques in complete arch implant cases with high angulations.

Is There a Role for Absorbable Metals in Surgery? A Systematic Review and Meta-Analysis of Mg/Mg Alloy Based Implants

Magnesium (Mg) alloys have received attention in the literature as potential biomaterials for use as absorbable implants in oral and maxillofacial and orthopedic surgery applications. This study aimed to evaluate the available clinical studies related to patients who underwent bone fixation (patients), and received conventional fixation (intervention), in comparison to absorbable metals (comparison), in terms of follow-up and complications (outcomes). A systematic review and meta-analysis were performed in accordance with the PRISMA statement and PROSPERO (CRD42020188654), PICO question, ROBINS-I, and ROB scales. The relative risk (RR) of complications and failures were calculated considering a confidence interval (CI) of 95%. Eight studies (three randomized clinical trial (RCT), one retrospective studies, two case-control studies, and two prospective studies) involving 468 patients, including 230 Mg screws and 213 Titanium (Ti) screws, were analyzed. The meta-analysis did not show any significant differences when comparing the use of Mg and Ti screws for complications (p = 0.868). The estimated complication rate was 13.3% (95% CI: 8.3% to 20.6%) for the comparison group who received an absorbable Mg screw. The use of absorbable metals is feasible for clinical applications in bone surgery with equivalent outcomes to standard metal fixation devices.

Status of Sleep Apnea and Snoring Disorder Curriculum in U.S. Advanced Education Prosthodontic Programs

PURPOSE

To assess the management of sleep apnea and snoring disorders in Advanced Education Programs in Prosthodontics (AEPP) in the United States.

MATERIALS AND METHODS

A 51 item, online survey was sent to program directors at 48 AEPPs in the United States in 2015. Data results were analyzed descriptively.

RESULTS

Thirty-five program directors responded to the survey. Twenty-four (68.6%, N = 35) programs report not having a dedicated course for the treatment of sleep apnea and snoring disorders. The majority (94.3%) of programs chose to treat sleep disordered breathing with oral appliance therapy and 80.0% (N = 35) of programs utilize customized sleep apnea oral devices. However, only 48.6% (N = 35) and 51.4% (N = 35) of programs regularly address sleep apnea and snoring disorders at initial examination during the comprehensive exam and medical history questionnaire, respectively.

CONCLUSIONS

The confidence interval for this survey is 8.71 at a confidence level of 95% due to a response rate of 72.9%. This confidence interval suggests there is responder bias in the survey results. Therefore, the results of this survey provide a suggestion of how sleep disorders are managed in AEPPs. Programs appear to be consistent among each other with regards to treatment modalities for sleep disordered breathing. The results suggest that patients are not screened enough to receive treatment addressing sleep disorders.

Prosthodontic Resident Selection by Postdoctoral Dental Matching Program: A National Survey by Participating Program Director

PURPOSE

The purpose of this study was to obtain information about the resident selection and Match process that occurred for the Commission on Dental Accreditation (CODA)-accredited Advanced Education in Prosthodontics program in North America from the program directors' perspective, after the first year of implementation.

MATERIALS AND METHODS

The list of Advanced Education in Prosthodontics program in CODA-accredited North American institutions was obtained from the ACP central office, and the directors of each program were identified. The surveys were distributed to 48 program directors online and results were compiled.

RESULTS

Out of 48 programs, 43 directors responded to and completed the survey (90.0%), where 35 programs participated in the Match process, 5 did not, and 3 were omitted due to incomplete surveys. While the majority of programs did not see any changes in their applicant pool or their quality, 10 programs (25.0%) observed a number of increases in the application and 13 programs (32.5%) observed an increase in the quality of the applications. Among the 35 programs that participated in the Match process, the main reasons for their participation were "fairness" (48.2%), "did not want to keep moving up interview dates" (23.2%), and "have applicants come to interview as planned" (21.4%). Thirty-three programs reported that 75% to 100% of the invited applicants came to the interview (76.7%). The majority of programs that participated in Match expressed satisfaction with the process (29/33, 80.6%). Sixteen programs (45.7%) reported that they matched with 100% of their first selections.

CONCLUSION

Overall response of reintroduction of the Match process for advanced prosthodontic resident selection was very positive for majority of the program directors.

Long-term stainability of interim prosthetic materials in acidic/staining solutions

OBJECTIVE

To evaluate the long-term color stainability, translucency, and contrast ratio (CR) of different resins used to fabricate interim prostheses after immersion in acidic/staining solutions.

MATERIALS AND METHODS

A total of 160 specimens were divided into 16 groups (n = 10) according to the material (heat-polymerized acrylic resin [HPAR], auto-polymerized acrylic resin [APR], nanoparticulated bis-acrylic resin [BR], and prefabricated poly(methyl methacrylate) block for CAD/CAM [CADR]) and immersion solutions (artificial saliva, cola beverage, coffee, and red wine). A spectrophotometer was used before and after each immersion period (7, 14, 28, 90, and 180 days). Color differences (CIEDE2000 and CIELab) were calculated. A three-way repeated-measures analysis of variance and Bonferroni test (α = .05) were used.

RESULTS

After 180 days, the APR presented the highest value for coffee and the CADR presented the smallest value for the cola (P < .001). For the CR, the highest values were obtained at 180 days for BR in coffee (1.35) and wine (1.18) (P < .001). Higher translucency parameters were obtained in the BR and CADR in the initial, 14, 28, and 90 days (P < .001).

CONCLUSIONS

From the greatest to the smallest staining potential, the solutions were classified as: wine > coffee > cola beverage > saliva, while for the materials as: APR > BR > HPAR > CADR.

CLINICAL SIGNIFICANCE

The knowledge of the long-term optical behavior of interim prosthetic materials is important for clinicians to decide which material to use to match the dietary intake of their patients and their esthetic demands. Prefabricated blocks for CAD/CAM systems have been shown to maintaining their optical characteristics even after a long period of immersion in acidic/staining solutions.

Retrospective Evaluation of the Status of Advanced Dental Education in Prosthodontics from 2006 to 2016

The aim of this study was to analyze information about advanced education programs in prosthodontics (AEPPs) collected in American Dental Association (ADA) surveys on advanced dental education from 2006-07 to 2016-17. Data recorded included number of AEPPs and information on program directors, applicants, and enrollees in AEPPs. The results showed that, from 2006 to 2016, there was an increase in the number of AEPPs and enrollment of prosthodontic residents, and the number of applicants per program more than doubled. Despite these increases, steps are needed to increase the number of underrepresented minority residents in prosthodontics. Also, a periodic survey of prosthodontic residents to identify their goals, experiences during training, and career plans could benefit the specialty by providing more insight into the future prosthodontic workforce.

Improving Polymethyl Methacrylate Resin Using a Novel Titanium Dioxide Coating

PURPOSE

The objective of this study was to improve the surface characteristics of poly (methyl methacrylate) (PMMA) by developing a novel, thin film coating process and to characterize the resulting coated surface.

MATERIALS AND METHODS

An atomic layer deposition (ALD) technique was developed to deposit a titanium dioxide (TiO₂ ) nano-thin film on PMMA. The surface wettability for both coated and uncoated PMMA was determined by measuring water contact angle. Wear resistance was assessed using a mechanical tooth-brushing device with a 50 g load for 6000 strokes after 5 months of water storage. A denture cleanser challenge test was performed by using sonication in 3.8% sodium perborate for 1 hour with aged specimens. X-ray photoelectron spectroscopy (XPS) was used before and after the brushing test and challenge test to analyze the PMMA surface chemical composition. The mechanical strength of coated and uncoated PMMA was measured using a three-point bending test. Surface microbial interactions were also evaluated by assessing Candida albicans biofilm attachment.

RESULTS

Nano-TiO₂ coating (30 nm thick) was successfully deposited on PMMA at 65°C. After coating, water contact angle decreased from 70° to less than 5°. After brushing test, the coating remained intact. XPS analysis revealed no loss of TiO₂ from coated specimens following brushing and denture cleanser sonication for 1 hour. There was no statistically significant difference in mechanical strength (MPa) (mean ± SD) between PMMA (139.4 ± 11.3) and TiO₂ -PMMA (160.7 ± 37.1) (p = 0.0995). C. albicans attachment decreased by 63% to 77% on the coated PMMA surface.

CONCLUSIONS

ALD is a promising technique to modify surface properties of PMMA and resulted in a stable adherent thin film. By depositing a TiO₂ coating, PMMA surface properties may lead to significantly reduced microorganism adhesion and easier pathogen removal from PMMA. For patients who wear dentures, reducing the oral microbial biofilm burden using a TiO₂ -coated PMMA surface could positively impact their oral and systemic health.

U.S. Maxillofacial Prosthetics Programs: Fellows' and Directors' Perspectives

Maxillofacial prosthetics (MFP) programs in the U.S. select only a limited number of applicants for fellowship positions. The aims of this study were to survey MFP fellows about which factors influenced their choice of programs and to survey MFP directors about what they considered critical factors in the selection process. Surveys were sent to all eight directors and 13 fellows at all eight U.S. MFP programs in June 2015. The directors' questions asked about general information, resident selection process, letters of recommendation, interview process, and decision process. The fellows' questions addressed their demographics, program-related factors, and future goals. The directors' surveys were sent directly to the directors, and the fellows' surveys were sent to the directors for distribution. The survey response rate for the directors was 87.5% (N=7), and that of the fellows was 53.8% (N=7). In selecting fellows for programs, responding directors reported the interview process was most important, followed by letters of recommendation, personal statement, and prosthodontic program grades. Responding fellows reported that location, variety of treatment, patient volume provided, and clinical education were crucial components in their choice of program. This information may be useful to MFP programs and fellows in the continuing development of this specialty.

Research Productivity of Directors of U.S. Advanced Education in Prosthodontics Programs

The aims of this study were to measure the research productivity of directors of U.S. advanced education in prosthodontics programs (AEPP) and to identify associations between the directors' publication metrics and professional characteristics. A list of AEPP directors was obtained from the American College of Prosthodontists website in December 2015. Information on gender, academic rank, and highest degree was collected from the institutional website for each individual. Citation databases (Scopus and Google Scholar) were searched for each director's h-index and i10-index (both indexes are based on numbers of citations of the author's articles) and total numbers of publications and citations. The search identified 50 AEPP directors. The majority were male and had a primary appointment at a university. Most held the rank of associate professor or professor and held both DDS and MS degrees. The mean h-index and i10-index of all directors were 6.32±6.97 and 6.84±10.77, respectively. Their mean numbers of publications and citations were 24.60±31.21 and 288.40±625.97, respectively. The analysis showed that the program directors affiliated with a university had significantly higher mean values for all indexes than those of non-university-affiliated program directors. Professors had productivity metrics significantly higher than those of other ranks in all measures of research productivity.

Dose-response effect of chlorhexidine on a multispecies oral biofilm formed on pure titanium and on a titanium-zirconium alloy

This study aimed to test the dose-response effect of chlorhexidine on multispecies biofilms formed on commercially pure titanium (cpTi) and titanium-zirconium (TiZr) alloy. Biofilms were formed on cpTi and TiZr discs and treated two times per day with five different chlorhexidine concentrations (0.12, 0.20, 0.50, 1, 2%). The biofilms were collected for microbiological, biochemical and microscopic analyses. The significance of differences among groups was evaluated by linear regression, ANOVA, Bonferroni and Tukey tests. The mean number of colony-forming units decreased as the chlorhexidine concentration increased for both cpTi and TiZr (p < 0.05). The maximum effect was observed with the 0.5% concentration. Confocal microscopy images suggested an increase in the number of dead bacterial cells with increased chlorhexidine concentration. The biofilm pH increased after chlorhexidine exposure (p < 0.05). Chlorhexidine showed an antimicrobial dose-response effect in controlling biofilm on cpTi and TiZr. 0.5% chlorhexidine can be used to achieve the maximum antimicrobial effect on both materials.

Enhanced Bioactivity of Collagen Fiber Functionalized with Room Temperature Atomic Layer Deposited Titania

Surface modifications of a biomaterial like collagen are crucial in improving the surface properties and thus enhancing the functionality and performance of such a material for a variety of biomedical applications. In this study, a commercially available collagen membrane's surface was functionalized by depositing an ultrathin film of titania or titanium dioxide (TiO₂) using a room temperature atomic layer deposition (ALD) process. A novel titanium precursor-oxidizer combination was used for this process in a custom-made ALD reactor. Surface characterizations revealed successful deposition of uniform, conformal TiO₂ thin film on the collagen fibrillar surface, and consequently, the fibers became thicker making the membrane pores smaller. The in vitro bioactivity of the ALD-TiO₂ thin film coated collagen was investigated for the first time using cell proliferation and a calcium phosphate mineralization assay. The TiO₂-coated collagen demonstrated improved biocompatibility promoting higher growth and proliferation of human osteoblastic and mesenchymal stem cells when compared to that of noncoated collagen. A higher level of calcium phosphate or apatite formation was observed on ALD modified collagen surface as compared to that on noncoated collagen. Therefore, this novel material can be promising in bone tissue engineering applications.

Wear and Corrosion Interactions at the Titanium/Zirconia Interface: Dental Implant Application

PURPOSE

Dental implants have been shown to have predictable success, but esthetic complications often arise. To reduce tissue shadowing from titanium, zirconia abutments may be used; however, the literature suggests that the use of zirconia leads to greater destruction of the implant interface that may result in biological complications such as titanium tattoos and heavy metal toxicity. Previous studies have examined the mechanical aspects of this implant/abutment relationship, but they have not accounted for the corrosive degradation that also takes place in the dynamic environment of the oral cavity. This study investigated the combined effect of both wear and corrosion on the materials at the implant and abutment interface.

MATERIALS AND METHODS

Using a simulated oral tribocorrosive environment, titanium (Ti) and zirconia (Zr) abutment materials were slid against titanium and Roxolid implant alloys. The four couplings (Ti/Ti, Ti/Rox, Zr/Ti, Zr/Rox) were selected for the tribocorrosion tests (N = 3). The testing was conducted for 25K cycles, and the coefficient of friction (CoF) and voltage evolution were recorded simultaneously. Following the tribocorrosion assays, the wear volume loss was calculated, and surface characterization was performed. Statistical analysis was completed using a one-way ANOVA followed by post-hoc Bonferroni comparisons.

RESULTS

Zr/Ti groups had the highest CoF (1.1647), and Ti/Ti had the lowest (0.5033). The Zr/Ti coupling generated significantly more mechanical damage than the Ti/Ti group (p = 0.021). From the corrosion aspect, the Ti/Ti groups had the highest voltage drop (0.802 V), indicating greater corrosion susceptibility. In comparison, the Zr/Roxolid group had the lowest voltage drop (0.628 V) and significantly less electrochemical degradation (p = 0.019). Overall, the Ti/Ti group had the largest wear volume loss (15.1 × 10⁷ μm³ ), while the Zr/Ti group had the least volume loss (2.26 × 10⁷ μm³ ). Both zirconia couplings had significantly less wear volume than the titanium couplings (p < 0.001).

CONCLUSIONS

This study highlights the synergistic interaction between wear and corrosion, which occurs when masticatory forces combine with the salivary environment of the oral cavity. Overall, the zirconia groups outperformed the titanium groups. In fact, the titanium groups generated 5 to 6 times more wear to the implant alloys as compared with the zirconia counterparts. The best performing group was Zr/Ti, and the worst performing group was Ti/Ti.

Patient-Reported and Clinical Outcomes of Implant-Supported Fixed Complete Dental Prostheses: A Comparison of Metal-Acrylic, Milled Zirconia, and Retrievable Crown Prostheses

The purpose of this retrospective study was to assess the incidence of biologic and technical complications for implant-supported fixed complete dental prostheses (IFCDPs) and their relationship to oral health-related quality of life (OHQoL) and patient-reported outcomes. Metal-acrylic (MA), retrievable crown (RC), monolithic zirconia (MZ), and porcelain veneered zirconia (PVZ) prostheses were included. Patients who received an IFCDP at least 1 year prior to recall were identified. Exclusion criteria were: (1) an opposing complete denture and (2) time in service &gt;70 months. A total of 37 patients with 49 prostheses, including 22 MA, 14 RC, 7 MZ, and 6 PVZ prostheses were recalled. Patient-reported outcomes were assessed via OHIP-49 (Oral Health Impact Profile) and a scripted interview with open-ended questions. All designs had high complication rates (12 of 22 MA, 10 of 14 RC, 2 of 7 MZ, and 5 of 6 PVZ). The most common complications were: (1) MA: posterior tooth wear, (2) RC: chipping and fracturing of the restorations, (3) MZ: wear of opposing restorations, and (4) PVZ: chipping of opposing restorations. Average OHIP-49 scores ranged from 7 to 29, indicating high OHQoL, patient satisfaction, regardless of prosthetic design (P = .16). The standardized interview highlighted that although most patients were extremely satisfied (73%), some continued to be bothered by material bulk (14%) and felt that maintenance of oral hygiene was excessively time-consuming (16%). In the context of this study, despite high complication rates and maintenance needs, all IFCDP designs resulted in high OHQoL and patient satisfaction.

Effect of brushing and thermocycling on the shade and surface roughness of CAD-CAM ceramic restorations

STATEMENT OF PROBLEM

The effects of toothbrushing (B) and thermocycling (TC) on the surface texture of different materials with various fabrication processes have been investigated. However, studies of computer-aided design and computer-aided manufacturing (CAD-CAM) ceramic restorations are limited.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of B and TC on the color stability and surface roughness of extrinsically characterized and glazed CAD-CAM ceramic restorations.

MATERIAL AND METHODS

Lithium disilicate CAD ceramic (n=90) and zirconia ceramic (n=90) were studied. All specimens were crystallized/sintered, characterized, and glazed following the manufacturer's recommendation. The specimens were divided into 9 different groups: B, TC, and a combination of B plus TC (B+TC). Brushing was performed at 50 000, 100 000, and 150 000 cycles, simulating an oral environment of 5, 10, and 15 years. Thermocycling was performed at 6000, 12 000, and 18 000 cycles, simulating an oral environment of 5, 10, and 15 years. Brushing plus TC was performed with the combination of the 50 000 cycles of B, then 6000 cycles of TC, and 10 000 cycles of B, then 12 000 cycles of TC, and 15 000 cycles of B, then 18 000 cycles of TC. The color and surface roughness of each specimen were measured before and after all interventions with simulated cycles. Color differences (ΔE) and surface roughness (ΔR_a) data were analyzed using 2-way ANOVA, followed by the least significant difference test (α=.05). The correlation between ΔE and ΔR_a was statistically analyzed using the Pearson correlation analysis.

RESULTS

Within the lithium disilicate CAD groups, intervention did not result in any significant differences in color change (P>.05). Within the zirconia groups, a 15-year clinical simulation revealed significantly higher ΔE values than a simulated 5-year exposure (P=.017). Increased simulated cycles showed significantly higher R_a values for all groups. Within the zirconia groups, B revealed significantly smoother surfaces than TC (P<.001) and B+TC interventions (P<.001). For the zirconia, simulating B+TC for15 years revealed significantly higher R_a values than the groups of B+TC for 5 years (P<.001) and B+TC for 10 years (P=.003). No correlation (lithium disilicate CAD, r=.079; P=.462; zirconia, r=.001; P=.989) was found between the color change and surface roughness.

CONCLUSIONS

For both lithium disilicate CAD and zirconia, color changes were below the selected clinical perceptible threshold (ΔE=2.6) after all intervention and simulated cycles. All mean surface roughness measurements were below 0.2 μm. Generally, the surface of both lithium disilicate CAD and zirconia became rougher. No correlation was found between color difference and surface roughness for either material.

Integration of Digital Dentistry into a Predoctoral Implant Program: Program Description, Rationale, and Utilization Trends

A recently revised predoctoral implant curriculum at the University of Illinois at Chicago College of Dentistry integrated digital dentistry into both the preclinical dental implant course and clinical activities. Traditionally, competence in the didactic and clinical parts of predoctoral education in single tooth implant restorations has emphasized the analog impression technique and subsequent mounting of soft tissue working casts. However, computer-aided design/computer-aided manufacturing (CAD/CAM) implant restorations can play a significant role in predoctoral dental education utilizing digital technologies. The goal of the curriculum expansion is to transition from analog to partially digital and, finally, complete digital workflow. The aim of this article is to describe the specific components, implementation, and rationale for the new digitally integrated implant curriculum and present short-term clinical utilization trends.