Management of Edentulous Patients

Impact of Printing Orientation on the Accuracy of Additively Fabricated Denture Base Materials: A Systematic Review

Printing orientation is one of the printing parameters that affect the properties of three-dimensional (3D)-printed resins. Different printing orientations and directions have been suggested; however, no clear and specific orientations are recommended in the literature in terms of the printing orientation effect on the accuracy and fit of 3D-printed removable dental prostheses. This review aimed to evaluate the effect of printing orientation on the fit and accuracy of 3D-printed removable dental prostheses. The PubMed, Scopus, and Web of Science databases were searched for published articles that investigated the effect of printing orientations on the accuracy and fit of the 3D-printed denture base. Full-length English published articles were searched between January 2010 and December 2023, which examined topics related to printing orientations, building angles, 3D printing, printing technology, accuracy, dimensional changes, internal fit, marginal integrity, marginal discrepancies, trueness, precision, and adaptation. Of the ten included studies, one investigated maxillary and mandibular denture bases, seven assessed maxillary denture bases, and two evaluated mandibular bases. Different printing orientations, ranging from 0° to 315°, were explored, with a higher prevalence of 0°, 45°, and 90°. The included studies utilized stereolithography and digital light processing printing technologies. High accuracy was observed at 45°, followed by 90. Additional struts and bars on the cameo surface increased the accuracy of the 3D-printed denture base. These results shows that printing orientation has a significant effect on the accuracy of 3D-printed resin, with 45° exhibiting the highest accuracy. In addition to the support structure, the density and position can impact the accuracy.

What Is the Survival Rate of Implants Loaded Immediately with a Branemark Protocol Prosthesis? A Review

The aim of this review was to determine the survival rate of implants loaded immediately with a Branemark protocol prosthesis. An electronic search was performed in the PubMed/MEDLINE database from 2006 to February 2024, using a combination of Medical Subject Headings descriptors: "completely edentulous" and "immediate loading." Human clinical articles in English that evaluated the survival rate of implants loaded immediately with a Branemark protocol prosthesis after placement in the bone were included. A total of 546 articles were identified, of which 15 were included in this study. The 15 articles included in the literature showed a high implant survival rate (more than 93%) after immediate loading.

In vitro evaluation of the impact of intraoral scanner, scanning aids, and the scanned arch on the scan accuracy of edentulous arches

PURPOSE

To assess the accuracy of complete maxillary and mandibular edentulous arch scans obtained using two different intraoral scanners (IOSs), with and without scanning aids, and to compare these results to those obtained using conventional impression methods.

MATERIALS AND METHODS

Two IOSs were used (TRIOS 4 [TRI] and Emerald S [EMR]) to scan maxillary and mandibular typodonts. The typodonts were scanned without scanning aids [TRI_WSA and EMR_WSA groups] (n = 10). The typodonts were then scanned under four scanning aid conditions (n = 10): composite markers [TRI_MRK and EMR_MRK groups], scanning spray [TRI_SPR and EMR_SPR groups], pressure indicating paste [TRI_PIP and EMR_PIP groups], and liquid-type scanning aid [TRI_LQD and EMR_LQD groups]. Conventional impressions of both arches were also made using irreversible hydrocolloids in stock trays [IHC] and using polyvinyl siloxane (PVS) impression material in custom trays (n = 10) which were digitized using a laboratory scanner. Using a metrology software program, all scans were compared to a reference scan in order to assess trueness and to each other to assess precision. Trueness and precision were expressed as the root mean square (RMS) of the absolute deviation values and the statistical analysis was modeled on a logarithmic scale using fixed-effects models to meet model assumptions (α = 0.05).

RESULTS

The main effect of arch (p = 0.004), scanner (p < 0.001), scanning aid (p = 0.041), and the interaction between scanner and scanning aid (p = 0.027) had a significant effect on mean RMS values of trueness. The arch (p = 0.015) and scanner (p < 0.001) had a significant effect on the mean RMS values of precision. The maxillary arch had better accuracy compared to the mandible. The TRIOS 4 scanner had better accuracy than both the Emerald S scanner and conventional impressions. The Emerald S had better precision than conventional impressions. The scanning spray and liquid-type scanning aids produced the best trueness with the TRIOS 4 scanner, while the liquid-type scanning aid and composite markers produced the best trueness for the Emerald S scanner.

CONCLUSION

The scanned arch and the type of scanner had a significant effect on the accuracy of digital scans of completely edentulous arches. The scanning aid had a significant effect on the trueness of digital scans of completely edentulous arches which varied depending on the scanner used.

In vitro analysis of monomer leaching in modern dental materials: CAD milled, printed, traditional heat-processed, and auto-polymerizing denture base resins

PURPOSE

Denture fabrication has shifted from traditional heat-processed and auto-polymerizing materials to computer-aided design and computer-aided manufacturing (CAD-CAM) milled and printed materials. The monomer in traditional materials can induce an allergic reaction in some patients. With the rise in the edentulous population and increasing demand for the fabrication of dentures, these newer materials should be studied for monomer leaching. The purpose of this study was to evaluate the ratio of residual monomer in materials being used for denture bases: CAD-milled polymethylmethacrylate (PMMA), printed denture base resin, heat-processed PMMA, and auto-polymerizing PMMA comparatively.

MATERIALS AND METHODS

Milled, printed, heat-activated, and auto-polymerizing denture base specimens (n = 3 for each group, each test run three times) were fabricated according to manufacturer recommendations. Specimens were first immersed in deuterated chloroform (CDCl3), a deuterated organic solvent, to evaluate monomer leaching and to observe physical properties of the materials. NMR spectroscopy was used to evaluate the dissolution of materials and residual monomer to crosslinked polymer ratios at 1, 4, and 9 days. A second group of specimens was then immersed in deuterium oxide (D2O) to evaluate if the residual monomers would leach out of the system. The solution was then analyzed using nuclear magnetic resonance (NMR) spectroscopy for 1 month. The deuterated forms of chloroform (CDCl3) and water (D2O) were used to enable sample characterization by NMR.

RESULTS

While the heat-processed, auto-polymerizing, and milled specimens possessed residual monomers, no significant monomer leaching was noted in the printed specimen, while immersed in CDCl3. Similarly, the printed specimen was most resistant to dissolution, as compared to the rest; dissolution of the specimen is indicative of little to no cross-linking. No detectable dissolution of monomer was seen when all specimens were immersed in D2O for up to 1 month.

CONCLUSIONS

Residual monomers were not found in the printed denture material in this study in either CDCl3 or D2O, whereas CAD-milled and traditionally processed denture bases still have residual monomers within their respective systems when immersed in organic solvent. None of the specimens tested leached monomers into D2O.

Application of organoselenium in inhibiting Candida albicans biofilm adhesion on 3D printed denture base material

PURPOSE

Denture Stomatitis, a chronic mucosal inflammation associated with Candida albicans, is common among denture wearers. Several health conditions have been linked to chronic Candida infections. The complex, multifactorial nature of denture stomatitis requires the continuous pursuit of effective long-term solutions. The present in vitro study investigated the effect of incorporating organoselenium into 3D-printed denture base resin on C. albicans adhesion and biofilm formation.

MATERIALS AND METHODS

Thirty disks were fabricated using 3D-printed denture base resin and assigned to three experimental groups (10/group): disks without organoselenium (control), disks with 0.5% organoselenium (0.5%SE), and disks with 1% organoselenium (1%SE). Each disk was incubated with approximately 1 × 106 cells/mL of C. albicans for 48 h. Microbial viability (CFU/mL) was quantified by the spread plate method, while Confocal laser scanning microscopy and scanning electron microscope were performed for quantifying the biofilm thickness and examining biofilm morphology, respectively. Data were analyzed using One-way ANOVA with Tukey's multiple comparisons test.

RESULTS

CFU/mL was significantly (p < 0.05) higher in Control when compared with 0.5%SE and 1%SE, but no significant difference between 0.5%SE and 1%SE. A similar trend was observed with biofilm thickness except that there was no significant difference between the Control and 0.5%SE. There was C. albicans biofilm adhesion on the Control disks, with yeast cells and hyphae formation, whereas on 0.5%SE and 1%SE, there was inhibition of yeast cells transition to hyphae formation.

CONCLUSIONS

Incorporation of organoselenium into 3D-printed denture base resin was effective in reducing C. albicans biofilm formation and growth on denture base material.

Impact of intraoral scanner, scanning strategy, and scanned arch on the scan accuracy of edentulous arches: An in vitro study

STATEMENT OF PROBLEM

The scanning strategy used when making complete arch digital scans affects the accuracy of the scan, and the accuracy of the strategy may be influenced by the scanner used. However, these effects have not been investigated thoroughly with complete arch edentulous scanning.

PURPOSE

The purpose of this in vitro study was to determine the effect of scanning strategies and the scanned arch on the accuracy of complete arch edentulous scans using 2 intraoral scanner (IOS) systems.

MATERIAL AND METHODS

Two IOSs were used (TRIOS 4 and Emerald S) to scan maxillary and mandibular typodonts using 6 scanning strategies (test scans), and conventional impressions of both arches were also made. By using a metrology software program, test scans were superimposed onto a reference scan, and the root mean square (RMS) of the absolute deviation values was calculated to express trueness. The sample with the best trueness was used as reference onto which the remaining samples from the same group were superimposed, and the RMS of the absolute deviation values was calculated to express precision. Statistical modeling was applied using the fixed effects models (α=.05).

RESULTS

The main effects of scanner and strategy significantly impacted the trueness RMS values (P<.001), with significant interactions between them (P=.012). The main effects of scanner, strategy, and arch significantly impacted the precision of RMS values (P=.004), (P=.033), and (P=.023). Conventional impressions and the TRIOS 4 scanner had comparable accuracy, while the Emerald S scanner was inferior to both. P-O-B had the highest overall accuracy and strategy ZZ had the worst. Better precision was found with the maxillary arch.

CONCLUSIONS

The scanner type and scanning strategy significantly impacted the accuracy of the digital scans of completely edentulous arches, with a significant interaction between scanner and strategy. The arch being scanned had a significant effect on scan precision but not on scan trueness.

Evaluation of open-face maxillary complete denture for patients with prominent premaxilla: a crossover study

BACKGROUND

The establishment of good facial esthetics is one of the main objectives of complete denture construction. Unfortunately, it may be the caused issue for patients having a prominent premaxilla due to excessive lip support by the labial flange of the maxillary denture. Open-face dentures (OFD) may suggest suitable prosthetic management for these patients. However, clinical evidence regarding the efficiency of OFD is scarce.

METHODS

A total of 38 completely edentulous participants having prominent premaxilla and skeletal class I Angle's classification were enrolled in this study. Each participant received a mandibular complete denture and 2 opposing maxillary dentures; conventional (CD) and open-face (OFD). On the day of denture insertion, the participants were divided into 2 groups; CD-OFD and OFD-CD where CD-OFD group was instructed to use the mandibular denture and the maxillary CD for 3 months and then to use the maxillary OFD for another 3 months after a wash-out period of 2 weeks. While group OFD-CD was instructed to use the mandibular denture and the maxillary OFD for 3 months then to use the maxillary CD for another 3 months after a wash-out period of 2 weeks. The dislodging force of the maxillary dentures was evaluated using the universal testing machine and the patient perception of retention, esthetics, and comfort was evaluated using the Visual Analogue Scale (VAS). Evaluation was carried out 1 day, 1 month, and 3 months after denture insertion. The Student t-test was used to compare the 2 maxillary dentures and the intervals for each denture were compared by using the ANOVA test with repeated measures followed by a Post Hoc test (adjusted Bonferroni) for pairwise comparison.

RESULTS

The significance of the obtained results was judged at the 5% level (P value). The dislodging force and patient perception of retention did not show significant differences between the 2 dentures, while the perception of esthetics showed significant differences throughout the follow-up period. Perception of comfort showed an insignificant difference only at the 3-month interval.

CONCLUSIONS

Open-face maxillary dentures can be a suitable alternative for patients with prominent premaxilla to achieve satisfactory retention, aesthetics, and comfort.

Impact of Scanbody Geometry and CAD Software on Determining 3D Implant Position

The implementation of CAD software in the digital production of implant prosthetics stands as a pivotal aspect of clinical dentistry, necessitating high precision in the alignment of implant scanbodies. This study investigates the influence of scanbody geometry and the method of superimposing in CAD software when determining 3D implant position. A standardized titanium model with three bone-level implants was digitized to create reference STL files, and 10 intraoral scans were performed on Medentika and NT-Trading scanbodies. To determine implant position, the generated STL files were imported into the Exocad CAD software and superimposed-automatically and manually-with the scanbody geometries stored within the software's shape library. Position accuracy was determined by a comparison of the 3D-defined scanbody points from the STL matching files with those from the reference STL files. The R statistical software was used for the evaluation of the data. In addition, mixed linear models and a significance level of 0.05 were applied to calculate the p-values. The manual overlay method was significantly more accurate than the automatic overlays for both scanbody types. The Medentika scanbodies showed slightly superior precision compared to the NT-Trading scanbodies. Both scanbody geometry and the type of alignment in the CAD software significantly affect digital workflow accuracy. Manual verification and adjustment of the automatic alignment process are essential for precise implant positioning.

Influence of new complete dentures on the touch perception threshold and quality of life of edentulous patients

OBJECTIVE

To evaluate the touch perception threshold of the alveolar mucosa and quality of life of edentulous patients before (T0) and 30 days after (T1) the insertion of new complete dentures.

BACKGROUND

Touch perception is important so that edentulous patients can detect the position of complete dentures in their mouth.

MATERIALS AND METHODS

This study included 32 complete denture wearers with good oral and systemic health and no temporomandibular disorders for at least 5 years. At each time point (T0 and T1), two tests were performed (touch perception threshold and quality-of-life scale). The touch perception threshold (Von Frey or Semmes-Weinstein test) was assessed using nylon monofilaments on the regions of the alveolar mucosa of the maxilla and mandible. The Oral Health Impact Profile for edentulous individuals (OHIP-EDENT) was administered to evaluate oral health-related quality of life.

RESULTS

In the maxilla and mandible, the touch perception thresholds for all regions of the alveolar mucosa were significantly lower at T1 than at T0. The OHIP-EDENT mean scores showed that the overall quality of life was significantly better at T1 (3.6) than at T0 (4.7), and a significant improvement in quality of life was observed in all domains of the OHIP-EDENT at T1. For touch perception threshold, effect sizes ranged from 0.4 to 0.8; and for quality of life, effect sizes ranged from 0.4 to 1.0.

CONCLUSIONS

New complete dentures reduced the touch perception threshold of the alveolar mucosa of both edentulous arches and improved individuals' quality of life.

Rehabilitation of Edentulous Arch Using All-on-Four Treatment Protocol: A Case Report

In edentulous arches, alveolar ridge atrophy after tooth extraction is a common problem that affects patient comfort and quality of life. Implant-supported fixed restorations are a well-proven treatment option for edentulism. The concepts of implant dentistry have developed over time to produce better aesthetics and functional results. To reduce cantilever length and enable prostheses with 12 teeth, the all-on-four technique entails inserting two anterior implants axially and distally orienting two posterior implants. Compared to conventional loading, immediate loading offers various benefits without compromising quality. An instantaneous fixed provisional allows patients immediate function and preserves their quality of life while also promoting a high degree of patient satisfaction in terms of aesthetics, phonetics, mastication, and psychological comfort.

Are YouTube videos on complete arch fixed implant-supported prostheses useful for patient education?

STATEMENT OF PROBLEM

Complete arch fixed implant-supported prostheses have gained substantial popularity as a treatment option for patients with edentulism or a failing dentition. While YouTube is a leading source of health-related information videos, the usefulness and quality of videos on YouTube about complete arch fixed implant-supported prostheses are unclear.

PURPOSE

The purpose of this study was to evaluate the quality of videos on complete arch fixed implant-supported prostheses and assess their usefulness for the general population as an educational resource.

MATERIAL AND METHODS

An electronic search for "complete arch fixed treatment using dental implants" was conducted on YouTube on October 10, 2021. The videos in English with a duration between 4 and 20 minutes were considered for the analysis. A total of 89 videos were subjected to quantitative analysis by using a usefulness score. Additionally, to evaluate video quality, 5-point global quality scale (GQS) criteria were applied. A 1-way analysis of variance (ANOVA) was used to compare mean scores among different subgroups. The Pearson correlation analysis investigated the relationship among the usefulness score, GQS score, and video demographics, which include video content, source, type (academic or nonacademic), total views, and upload days (the days since the video was uploaded to YouTube) (α=.05).

RESULTS

The mean number of views for the 89 selected videos was 193 321 with a mean daily upload of 1241. The mean ±standard deviation usefulness score was 1.55 ±1.35, with 78.7% of the videos rated poor, 20.2% moderate, and 1.1% excellent. The majority of videos included procedures involved (44.9%) and advantages (41.9%), and the least discussed topics were contraindications (7.9%) and prognosis and survival (6.7%). The GQS scoring had a mean score of 1.98 ±0.78 out of a total score of 5. While statistically significant differences were not found among the video source, total views or upload days, and usefulness score (P>.05), significant differences were found between the type of videos and usefulness score (P<.001).

CONCLUSIONS

The majority of videos on complete arch fixed implant-supported rehabilitation were rated as poor in usefulness for patient education. Quality videos on implant-supported fixed rehabilitation were lacking on YouTube (GQS score <1.50), with most videos consisting of marketing or promotional content rather than unbiased educational information.

Maxillary bone augmentation with calvarial bone graft for immediate full-arch rehabilitation: Insights from a 10-year proof-of-concept retrospective analysis

OBJECTIVE

Evaluate the long-term outcomes of full-arch rehabilitation using immediate dental implant placement and continuous functional loading with full-fixed dental prostheses (FFDPs).

MATERIALS AND METHODS

Fifty-six patients received temporary implants (n = 327) at maxillary augmentation with calvarial bone. A provisional acrylic FFDP was immediately loaded onto these implants. After 6 months, the temporary implants were replaced with definitive implants (n = 326) and immediately loaded with a second provisional FFDP (N = 55). Subsequently, a baseline radiograph was taken following a 6-month healing period. The second bridge was then substituted with a definitive FFDP. Primary outcomes included peri-implant marginal bone level (MBL) and definitive implant survival. Secondary outcomes evaluated provisional implant and prostheses survival, complications, and patient satisfaction.

RESULTS

The provisional implants had a survival rate of 97.9%. One patient was excluded from further analysis due to loss of temporary implants and first FFDP. The definitive implant survival rate after 10 years was 92.2%, with a moderate but significant decrease in MBL between baseline radiography and 10 years later (-0.08 ± 0.18 vs. -0.24 ± 0.44). However, large individual variations were observed, with 65.8% of implants showing no bone loss and 9.2% showing loss ≥0.5 mm. Sinusitis was experienced by 14.3% of patients upon surgery. Patient satisfaction was high or reported no issues after protocol completion (80%). One patient lost all six definitive implants and definitive FFDP 8.2 years after implant placement.

CONCLUSIONS

The described protocol can be regarded as a long-term, highly successful method for full-arch rehabilitation of atrophied maxillae while enabling continuous masticatory and speaking functionality.

Effect of repair and surface treatments on the strength of digitally fabricated resin-based dental prostheses: A systematic review of in vitro studies

OBJECTIVE

This review investigated the current literature pertaining to the repairability of computer-aided design-computer-aided manufacturing (CAD-CAM) milled and three-dimensional (3D) printed resin-based dental prostheses (RBDPs) as well as the appropriate surface treatment for each repair material that will produce adequate repair bond strength.

DATA/SOURCES

PubMed, Web of Science, and Scopus databases were searched for published articles involving repair of CAD-CAM RBDPs between January 2010 and June 2023. Data were collected and analyzed to reveal the surface treatment effects, suggested repair materials, and strength of repaired RBDPs.

STUDY SELECTION

Out of 164 retrieved titles, 11 studies were included, of which five investigated the repair of 3D-printed RBDPs, three investigated the repair of CAD-CAM milled resins, and three investigated both materials. Additionally, of the included studies, seven investigated denture base resins, three studied provisional restoration resins, and one evaluated 3D-printed intraoral splints. Various surface treatments were suggested, with air-abrasive methods being the most commonly used. Different materials for resin repair were proposed and used, including auto-polymerized, reline, and composite resins. For 3D-printed resins, repair with Bis-acrylic/Bis-GMA composites improved repair strength.

CONCLUSION

Surface treatments positively affected the repair strength of conventional and milled RBDPs. However, challenges remain relevant to the repair of 3D-printed resins owing to composition mismatches and fabrication techniques. Therefore, further investigation is required to develop new 3D-printed resins.

CLINICAL SIGNIFICANCE

CAD-CAM milled resins have satisfactory repair strength, which increases with surface treatment. The repair of 3D-printed resins has proven challenging even with surface treatments. However, composite resins are the materials of choice.

Self-assessment skills of undergraduate dental students in the preclinical course of complete removable prosthodontics at Tehran University of Medical Sciences

INTRODUCTION

This study evaluated the self-assessment skills of third-year dental students regarding their performance in complete removable prosthodontics (CRP) preclinical course.

METHODS AND MATERIALS

This cross-sectional study was conducted on all third-year dental students attending the International Dental College of Tehran University of Medical Sciences. The students were requested to self-assess their performance in primary impression making, custom tray fabrication, border moulding, final impression making, master cast fabrication, record-base fabrication and tooth arrangement in CRP preclinical course. The performance of dental students in each step was scored by themselves and their mentors. Data were analysed by the Mann-Whitney U, Pearson's correlation and t-tests (α = 0.05).

RESULTS

Totally 25 male (55.6%) and 20 female (44.4%) dental students were evaluated. Significant differences were noted between male and female dental students in self-assessment scores regarding adequate extension of the custom tray (p = .027), the correct position of tray handle (p = .020), visibility of vestibular width and depth on the cast (p = .011), the coincidence of upper and lower midlines (p = .005) and correct orientation of maxillary and mandibular planes in the articulator (p = .036). The mean self-assessment score of female students was significantly higher than that of male students (p = .01). The scores given by the mentors were not significantly different for male and female students (p = .975). The difference between the self-assessment score of students and the mentor score was not significant (p = .067) either in males or in females (p > .05).

CONCLUSION

Undergraduate dental students favourably self-assessed their performance in all steps of the preclinical course of CRP, comparable with their mentor assessment.

Dental Technicians' Perception of the Quality of Dentists' Communication on the Fabrication of Removable Partial Dentures: A Cross-Sectional Study in Saudi Arabia

BACKGROUND

Effective and clear communication between the dentist and dental technician plays a vital role in rendering quality prostheses for patients. When fabricating a removable dental prosthesis, it is uncertain if the information received by the dental laboratory technician is clear and sufficient. This investigation aimed to assess dental technicians' perceptions of the quality of dentists' communication on the fabrication of removable partial dentures (RPDs) in Saudi Arabia.

METHODOLOGY

After obtaining the institutional review board (IRB) approval from Riyadh Elm University, Riyadh, Saudi Arabia, a cross-sectional survey on a convenient sample of 115 dental technicians registered with the Saudi Commission for Health Specialties was conducted in January 2022. The voluntary participation of 94 technicians fabricating RPDs was included. A 19-item online questionnaire was developed, including quality of written instruction, selection of impression trays, and impression materials for RPD fabrication, shared through Google Docs. Descriptive statistics were tabulated, and responses were displayed as a percentage of the total.

RESULTS

Of the 94 study subjects, 35% had less than five years of experience, 44% stated that they routinely receive work authorizations with clear instructions, 13% always used digital technology to fabricate prostheses, and 58% reported difficulty with communicated work authorization by dentists having less than five years of experience. Thirty-three respondents (35.1%) reported that 75% or more of the fabricated partial dentures were cast framework partials. Thirty-three respondents (35.1%) indicated that the master casts received for partial framework construction were usually accurate. Tooth alterations, however, were reported as usually adequate by only 28 respondents (29.8%). For creating the artificial gingiva portion of cast partials, 56 respondents (59.6%) preferred heat-cured acrylic resin. Furthermore, 40 respondents (42.6%) said that 75% or more of the requested partials were entirely made out of acrylic resin. Regarding case design discussions, 26 respondents (27.7%) always engaged with dentists, while 39 (41.5%) did so occasionally.

CONCLUSION

The obtained assessments pointed to the fact that dental technicians expressed a perception of inadequacy regarding the work authorizations provided by dentists for the fabrication of RPDs, where they seemingly felt that the instructions conveyed by the dentists were not sufficiently comprehensive or clear.

The Effect of Herbal Denture Adhesive on Patient Satisfaction in Comparison to Traditional Type

Background The aim of this study was to compare the responses of 30 denture wearers' opinions concerning the efficiency of two types of adhesives and estimate their satisfaction level using denture adhesive (DA). Materials and methods 30 completely edentulous patients were divided randomly into two groups. Each group received one type of DAs (SECURE, COREGA) and was instructed to follow the same sequence of application. Each type of adhesive was used for seven days, as recommended by the manufacturer. The patients were requested to fill out a questionnaire considering their opinion and satisfaction regarding denture retention, chewing ability and duration of adhesives. Results The majority of patients stated that the prosthetic DAs enhanced their retention, chewing, stability, and efficiency of dentures. There was a significant difference in patient satisfaction regarding denture retention in the mandible and the duration of the adhesive in the mouth. Concerning ability of the patient to remove the adhesive from their mouth, the taste, or the retention of the maxillary denture, there were no statistically significant differences between the two DAs. Conclusions The results of the present study showed that overall satisfaction of complete denture wearers was high significantly different when a herbal DA was applied. This includes improvements in their duration of retention effectiveness, greater stability, and retention of the lower mandibular dentures. To use DA effectively, patients should be oriented by their dentists. Patient education is essential to provide them with a better understanding of both the appropriate technique for applying DA and the possible outcome they may experience.

Influence of Fabrication Technique on Adhesion and Biofilm Formation of Candida albicans to Conventional, Milled, and 3D-Printed Denture Base Resin Materials: A Comparative In Vitro Study

The aim of this study was to evaluate the adhesion and biofilm formation of Candida albicans (C. albicans) on conventionally fabricated, milled, and 3D-printed denture base resin materials in order to determine the susceptibility of denture contamination during clinical use. Specimens were incubated with C. albicans (ATCC 10231) for 1 and 24 h. Adhesion and biofilm formation of C. albicans were assessed using the field emission scanning electron microscopy (FESEM). The XTT (2,3-(2-methoxy-4-nitro-5-sulphophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide) assay was used for the quantification of fungal adhesion and biofilm formation. The data were analyzed using GraphPad Prism 8.02 for windows. One-way ANOVA with Tukey's post hoc testing were performed with a statistical significance level set at α = 0.05. The quantitative XTT biofilm assay revealed significant differences in the biofilm formation of C. albicans between the three groups in the 24 h incubation period. The highest proportion of biofilm formation was observed in the 3D-printed group, followed by the conventional group, while the lowest candida biofilm formation was observed in the milled group. The difference in biofilm formation among the three tested dentures was statistically significant (p < 0.001). The manufacturing technique has an influence on the surface topography and microbiological properties of the fabricated denture base resin material. Additive 3D-printing technology results in increased candida adhesion and the roughest surface topography of maxillary resin denture base as compared to conventional flask compression and CAD/CAM milling techniques. In a clinical setting, patients wearing additively manufactured maxillary complete dentures are thus more susceptible to the development of candida-associated denture stomatitis and accordingly, strict oral hygiene measures and maintenance programs should be emphasized to patients.

Differences in complete denture longevity and replacement in public and private dental services: A propensity score-matched analysis of subsidised dentures in adult Australians across 20 years

OBJECTIVES

To examine the differences in treatment outcomes for patients who received subsidized complete dentures in private dental clinics and in public dental clinics over 20 years in Victoria, Australia.

METHODS

Between 2000 and 2019, 187 227 complete dentures were provided to eligible public patients by the Victorian public dental system. Of these, approximately 52% were provided to public patients in private clinics through the voucher system. Of the 97 107 participants who received denture care in private clinics, 70 818 were matched 1:1 by propensity score (PS) quantiles with participants who received denture care in public clinics. The PS matching balanced the characteristics between these two groups. Subsequently, a conditional logistic regression model investigated the binary outcome of denture replacement whilst a conditional Poisson regression modelled the number of years to denture replacement. A frailty Cox regression after PS matching investigated denture survival over time.

RESULTS

Dentures provided in public clinics had a mean time to replacement of 5.5 years (SD: 34.0) and 25.9% were replaced during the observation period. In the first year of denture service, incidence rate per person year (IR) for complete denture replacement in public clinics was 0.04 (95% CI: 0.04-0.04). Dentures provided in private clinics had a mean time to replacement of 6.5 years (SD: 3.8) with 29.4% replaced during the observation period. In the first year of denture service, the IR for complete denture replacement in private clinics was 0.02 (95% CI: 0.02-0.02), which was less than half that of the public IR. Multivariate analyses found that although private dentures were more likely to be replaced during the observation period than those provided in the public sector (odds ratio [OR]: 1.31, 95% CI: 1.28-1.35, p < .001), they had greater longevity (incidence rate ratio [IRR]: 1.23, 95% CI: 1.23-1.24, p < .001). Longer longevity of private dentures was also supported by the frailty Cox regression showing that private dentures had a reduced hazard of denture replacement over time (better survival) in comparison to public dentures (hazard ratio [HR]: 0.94, 95% CI: 0.92-0.97, p < .001). Probabilistic sensitivity analysis supported the study findings.

CONCLUSIONS

Increased denture longevity, higher rates of denture replacement and lower rates of early denture replacement were associated with receiving denture care in private clinics as compared with dentures provided in the public sector.

Use of CGF in Oral and Implant Surgery: From Laboratory Evidence to Clinical Evaluation

Edentulism is the condition of having lost natural teeth, and has serious social, psychological, and emotional consequences. The need for implant services in edentulous patients has dramatically increased during the last decades. In this study, the effects of concentrated growth factor (CGF), an autologous blood-derived biomaterial, in improving the process of osseointegration of dental implants have been evaluated. Here, permeation of dental implants with CGF has been obtained by using a Round up device. These CGF-coated dental implants retained a complex internal structure capable of releasing growth factors (VEGF, TGF-β1, and BMP-2) and matrix metalloproteinases (MMP-2 and MMP-9) over time. The CGF-permeated implants induced the osteogenic differentiation of human bone marrow stem cells (hBMSC) as confirmed by matrix mineralization and the expression of osteogenic differentiation markers. Moreover, CGF provided dental implants with a biocompatible and biologically active surface that significantly improved adhesion of endothelial cells on CGF-coated implants compared to control implants (without CGF). Finally, data obtained from surgical interventions with CGF-permeated dental implants presented better results in terms of optimal osseointegration and reduced post-surgical complications. These data, taken together, highlight new and interesting perspectives in the use of CGF in the dental implantology field to improve osseointegration and promote the healing process.

Spatiotemporal trends of disease burden of edentulism from 1990 to 2019: A global, regional, and national analysis

Background

Understanding the spatiotemporal trends in disease burden of edentulism is critical to reducing disease burden of edentulism and deploying medical resources. We assessed the changing patterns of disease burden of edentulism at global, regional, and national levels from 1990 to 2019.

Methods

Data on incident cases, prevalent cases, disability-adjusted life years (DALYs), and age-standardized rates (ASRs) of edentulism were extracted from the Global Burden of Disease 2019 Study. We calculated the estimated annual percentage change (EAPC) to quantify spatiotemporal trends in the ASRs of edentulism.

Results

In 2019, the number of prevalent cases and DALYs of edentulism were 35.2 and 9.6 million, and the ASPR and ASDR were 43.12/1,000 and 1.18/1,000, with EAPCs of -0.18 [95% confidence interval (CI): -0.28, -0.09] and -0.16[95% CI: -0.26, -0.07] from 1990 to 2019, respectively. Females and the elderly had a higher burden of edentulism. Although the ASPR, ASDR, and ASIR in the high SDI, high-middle SDI, and middle SDI regions showed a decreasing or stable trend, the absolute disease burdens of edentulism in these regions were still high. Although the absolute disease burdens of low SDI and low-middle SDI were low, their ASPR and ASDR showed an upward trend. In countries with high initial disease burden or high SDI, ASPR, ASDR, and ASIR showed stable or declining trends.

Conclusion

The absolute disease burden due to edentulism was increasing in many countries and regions. Countries should reduce the disease burden caused by edentulism by adopting measures including the prevention and treatment of dental caries and periodontal disease.

Influence of ZrO2 Nanoparticle Addition on the Optical Properties of Denture Base Materials Fabricated Using Additive Technologies

This study investigated the translucency of 3D-printed denture base resins modified with zirconium dioxide nanoparticles (ZrO₂NPs) under thermal cycling. A total of 110 specimens were fabricated and divided into 3 groups according to the materials, i.e., heat-polymerized resin, and 3D-printed resins (NextDent, and ASIGA). The 3D-printed resins were modified with 0, 0.5, 1, 3, and 5 wt.% of ZrO₂NPs. All the specimens were subjected to 5000 thermal cycles. The translucency was measured using a spectrophotometer. The results showed that the heat-polymerized resin had considerably higher translucency than the 3D-printed resins. Compared to the unmodified group, the translucency decreased significantly after adding 5% ZrO₂NPs to NextDent and 3% ZrO₂NPs to ASIGA resins. The highest translucency was achieved for NextDent by adding 0.5% ZrO₂NPs and for ASIGA without any ZrO₂NPs. It was found that the average concentration level in ASIGA was significantly higher than that in NextDent. These findings revealed that 3D-printed resins have lower translucency than heat-polymerized acrylic resin, and adding ZrO₂NPs at low concentrations did not affect the translucency of the 3D-printed resins. Therefore, in terms of translucency, 3D-printed nanocomposite denture base resins could be considered for clinical applications when ZrO₂NPs are added at low concentrations.

Evaluation of biofilm formation on acrylic resins used to fabricate dental temporary restorations with the use of 3D printing technology

Background

Temporary implant-retained restorations are required to support function and esthetics of the masticatory system until the final restoration is completed and delivered. Acrylic resins are commonly used in prosthetic dentistry and lately they have been used in three-dimensional (3D) printing technology. Since this technology it is fairly new, the number of studies on their susceptibility to microbial adhesion is low. Restorations placed even for a short period of time may become the reservoir for microorganisms that may affect the peri-implant tissues and trigger inflammation endangering further procedures. The aim of the study was to test the biofilm formation on acrylamide resins used to fabricate temporary restorations in 3D printing technology and to assess if the post-processing impacts microbial adhesion.

Methods

Disk-shaped samples were manufactured using the 3D printing technique from three commercially available UV-curable resins consisting of acrylate and methacrylate oligomers with various time and inhibitors of polymerization (NextDent MFH bleach, NextDent 3D Plus, MazicD Temp). The tested samples were raw, polished and glazed. The ability to create biofilm by oral streptococci (S. mutans, S. sanguinis, S. oralis, S. mitis) was tested, as well as species with higher pathogenic potential: Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans. The roughness of the materials was measured by an atomic force microscope. Biofilm formation was assessed after 72 h of incubation by crystal violet staining with absorbance measurement, quantification of viable microorganisms, and imaging with a scanning electron microscope (SEM).

Results

Each tested species formed the biofilm on the samples of all three resins. Post-production processing resulted in reduced roughness parameters and biofilm abundance. Polishing and glazing reduced roughness parameters significantly in the NextDent resin group, while glazing alone caused significant surface smoothing in Mazic Temp. A thin layer of microbial biofilm covered glazed resin surfaces with a small number of microorganisms for all tested strains except S. oralis and S. epidermidis, while raw and polished surfaces were covered with a dense biofilm, rich in microorganisms.

Conclusions

UV-curing acrylic resins used for fabricating temporary restorations in the 3D technology are the interim solution, but are susceptible to adhesion and biofilm formation by oral streptococci, staphylococci and Candida. Post-processing and particularly glazing process significantly reduce bacterial biofilm formation and the risk of failure of final restoration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02488-5.

3D-Printed Nanocomposite Denture-Base Resins: Effect of ZrO2 Nanoparticles on the Mechanical and Surface Properties In Vitro

Due to the low mechanical performances of 3D-printed denture base resins, ZrO2 nanoparticles (ZrO2NPs) were incorporated into different 3D-printed resins and their effects on the flexure strength, elastic modulus, impact strength, hardness, and surface roughness were evaluated. A total of 286 specimens were fabricated in dimensions per respective test and divided according to materials into three groups: heat-polymerized as a control group and two 3D-printed resins (NextDent and ASIGA) which were modified with 0.5 wt.%, 1 wt.%, 3 wt.%, and 5 wt.% ZrO2NPs. The flexure strength and elastic modulus, impact strength, hardness, and surface roughness (µm) were measured using the three-point bending test, Charpy’s impact test, Vickers hardness test, and a profilometer, respectively. The data were analyzed by ANOVA and Tukey’s post hoc test (α = 0.05). The results showed that, in comparison to heat-polymerized resin, the unmodified 3D-printed resins showed a significant decrease in all tested properties (p < 0.001) except surface roughness (p = 0.11). In between 3D-printed resins, the addition of ZrO2NPs to 3D-printed resins showed a significant increase in flexure strength, impact strength, and hardness (p < 0.05) while showing no significant differences in surface roughness and elastic modulus (p > 0.05). Our study demonstrated that the unmodified 3D-printed resins showed inferior mechanical behavior when compared with heat-polymerized acrylic resin while the addition of ZrO2NPs improved the properties of 3D-printed resins. Therefore, the introduced 3D-printable nanocomposite denture-base resins are suitable for clinical use.

In Vitro Analysis of Shear Stress: CAD Milled vs Printed Denture Base Resins with Bonded Denture Tooth

PURPOSE

As the fabrication of computer-aided design (CAD) milled and 3D printed denture base resins with bonded denture teeth increase in popularity, there is a need for research comparing the shear bond stress of milled and printed denture base resins with bonded denture teeth to that of a conventional heat processed denture base.

MATERIALS AND METHODS

Denture base resin specimens (n = 9) were fabricated according to manufacturers' instructions using a novel test design. Two milled (Ivobase CAD PMMA, Ivoclar Vivadent and Polident PMMA, Polident Dental) and two 3D printed (Denture Base LP Resin, Formlabs and Lucitone Digital Print, Dentsply Sirona) materials were used. Conventional heat processed polymethylmethacrylate was used as the control (Lucitone 199, Dentsply Sirona). Denture teeth (VITA Vitapan XL T44, #8, VITA Zahnfabrik) were bonded to their respective bases using denture tooth bonding agent (Ivobase CAD bonding system, Ivoclar). Specimens were aged in water for 600 hours at 37°C and loaded until failure in a Universal testing machine. Shear bond stress was calculated. All specimens were evaluated for mode of failure and select specimens under scanning electron microscope and vertical scanning interferometry. Data were analyzed with one-way ANOVA followed by Tukey test (IBM SPSS) and fracture analysis performed.

RESULTS

Shear stress was highest for the heat processed control (mean = 180 N ±26.76) and Polident test groups (mean = 180 N ± 34.90). Milled specimens were not significantly different from the control (p = 0.076 for IvoBase CAD and 1.00 for Polident), while the printed groups were significantly different from the control (p = 0.012 for Formlabs Denture Base Resin and p = 0.00 for Carbon Lucitone Digital Print). Milled denture base resins performed similarly to heat processed denture base resin and better than 3D printed denture bases.

CONCLUSION

For complete denture wearers, all resin materials used in this study may be clinically acceptable, as the sheer stress for all groups was higher than the reported maximum biting force of complete denture patients. However, for implant retained prostheses, the incorporation of additional retentive features should be considered when bonding denture teeth to printed bases. More research is needed to evaluate methods to increase the bond strength of denture teeth to printed denture base resins.

Adaptation to New Dentures and 5 Years of Clinical Use: A Comparison between Complete Denture and Mini-implant Mandibular Overdenture Patients based on Oral Health-Related Quality of Life (OHRQoL) and Orofacial Esthetics

Objective of work

It is unclear how long patients need to adapt to new dentures. This study assessed adaptation and five years of clinical use, comparing complete denture wearers (CDs) and mini-implant mandibular overdenture wearers opposing a maxillary CD (MDI-OD), based on oral health reported quality of life (OHRQoL) and orofacial esthetics (OES).

Material and Methods

A total of 36 subjects in the CD group (25 females) and 30 subjects in the MDI group (20 females) completed the 5-year study. All patients received new CDs, but in the MDI-OD group, four mini-implants were inserted interforaminally in the mandible before denture manufacture. Participants filled in the OHIP-EDENT and OES questionnaires one day after dentures’ delivery, on the 3^rd, 8^th, 15^th, 30^th day, and at the 1-, 3- and 5-year follow-up examinations. Statistical analysis comprised descriptive methods, X² test, independent t-test, Friedman, and Mann-Whitney test.

Results and Conclusions

Both groups' adaptation to new dentures was completed within a month. The MDI-OD group had significantly better OHRQoL in all follow-ups except for the 3^rd and 8^th day, probably due to soreness and pain, the reason why the MDI-OD group had limitation in functioning in the first days after new dentures’ delivery. Already after the third year and at the fifth year, OHRQoL worsened (p<0.01) in both groups. However it was significantly more pronounced in the conventional CD wearers (p<0.01) than in the MDI-OD group. Orofacial esthetics was highly scored in both groups. The scores dropped down only after three years, equally in both groups.

Keywords

OHRQoL, OES, prospective study, complete dentures, mini-implants, adaptation

MeSH Terms

Complete Dentures; Dental Implants; Quality of Life; Dental Esthetics

Titanium Dental Implants: An Overview of Applied Nanobiotechnology to Improve Biocompatibility and Prevent Infections

This review addresses the different aspects of the use of titanium and its alloys in the production of dental implants, the most common causes of implant failures and the development of improved surfaces capable of stimulating osseointegration and guaranteeing the long-term success of dental implants. Titanium is the main material for the development of dental implants; despite this, different surface modifications are studied aiming to improve the osseointegration process. Nanoscale modifications and the bioactivation of surfaces with biological molecules can promote faster healing when compared to smooth surfaces. Recent studies have also pointed out that gradual changes in the implant, based on the microenvironment of insertion, are factors that may improve the integration of the implant with soft and bone tissues, preventing infections and osseointegration failures. In this context, the understanding that nanobiotechnological surface modifications in titanium dental implants improve the osseointegration process arouses interest in the development of new strategies, which is a highly relevant factor in the production of improved dental materials.

Mandibular full-arch fixed prostheses supported by three-dental-implants: A protocol of an overview of reviews

INTRODUCTION

To minimize trauma and cost of treatment, oral health practitioners have successfully rehabilitated full arches by supporting the prostheses on four implants. However, there is no consensus whether less than four implants supporting full mandibular arches would provide similar clinical outcomes to other well-established all-on-four alternative.

OBJECTIVE

To identify, summarize, appraise, and compare the clinical outcomes evidence of three-implant fixed full-arch prostheses in completely edentulous mandibular patients.

MATERIALS AND METHODS

This overview of systematic reviews (OoSRs) will include secondary synthesis studies (i.e., systematic reviews with or without a meta-analysis). A three-step search strategy will be conducted in MEDLINE (Ovid), EMBASE (Ovid), Cochrane Database of Systematic Reviews, Scopus, Web of Science (WoS Core Collection), and Google Scholar. Grey literature and a manual search in 12 specialized journals will also be conducted. Three independent reviewers will screen all retrieved articles for eligibility, extract data and assess the methodological quality of the included studies. The results will be presented as tables or narrative synthesis. The studies will be evaluated for risk of bias by ROBIS and methodology quality by the AMSTAR-2 tool. If new primary studies are identified, a meta-analysis will be conducted. Certainty of the evidence will be assessed to answer the following focused research question: In edentulous mandibular patients, what are the implant and prostheses clinical outcomes of three-implant fixed full-arch prostheses compared to other all-on-x solutions?

DISCUSSION

There are some systematic reviews about the use of fixed complete dental prostheses supported by three implants; however, their clinical outcomes related to the other all-on-four plus solutions are conflicting. So, an overview on this topic is required to provide recommendations.

REVIEW REGISTRATION NUMBER

International prospective register of systematic reviews (PROSPERO) ID#: CRD42021262175. National Institute for Health Research (NIHR) and Centre for Reviews and Dissemination, University of York, York, United Kingdom.

Exploring variation of coverage and access to dental care for adults in 11 European countries: a vignette approach

BACKGROUND

Oral health, coupled with rising awareness on the impact that limited dental care coverage has on oral health and general health and well-being, has received increased attention over the past few years. The purpose of the study was to compare the statutory coverage and access to dental care for adult services in 11 European countries using a vignette approach.

METHODS

We used three patient vignettes to highlight the differences of the dimensions of coverage and access to dental care (coverage, cost-sharing and accessibility). The three vignettes describe typical care pathways for patients with the most common oral health conditions (caries, periodontal disease, edentulism). The vignettes were completed by health services researchers knowledgeable on dental care, dentists, or teams consisting of a health systems expert working together with dental specialists.

RESULTS

Completed vignettes were received from 11 countries: Bulgaria, Estonia, France, Germany, Republic of Ireland (Ireland), Lithuania, the Netherlands, Poland, Portugal, Slovakia and Sweden. While emergency dental care, tooth extraction and restorative care for acute pain due to carious lesions are covered in most responding countries, root canal treatment, periodontal care and prosthetic restoration often require cost-sharing or are entirely excluded from the benefit basket. Regular dental visits are also limited to one visit per year in many countries. Beyond financial barriers due to out-of-pocket payments, patients may experience very different physical barriers to accessing dental care. The limited availability of contracted dentists (especially in rural areas) and the unequal distribution and lack of specialised dentists are major access barriers to public dental care.

CONCLUSIONS

According to the results, statutory coverage of dental care varies across European countries, while access barriers are largely similar. Many dental services require substantial cost-sharing in most countries, leading to high out-of-pocket spending. Socioeconomic status is thus a main determinant for access to dental care, but other factors such as geography, age and comorbidities can also inhibit access and affect outcomes. Moreover, coverage in most oral health systems is targeted at treatment and less at preventative oral health care.

Is the Number of Appointments for Complete Denture Fabrication Reduced with CAD-CAM? A Literature Review

One of the key arguments in favor of digitally produced complete dentures (CDs) is the requirement for less patient visits in comparison to the conventional workflow. However, it is not yet clear if this argument is accurate; nor, if indeed the insertion of the complete dentures is achieved in fewer appointments, how many are required. The purpose of this literature review was to investigate the reported number of required patient visits for the production of digitally fabricated CDs. An electronic search was performed in PubMed/MEDLINE using three groups of keywords: “complete dentures”, “CAD/CAM”, and “Appointments” with their alternative forms. Out of the initial 157 results, 36 articles were automatically selected utilizing exclusion keywords. After consensus between the two examiners, eight articles were finally analyzed and presented in a table. The majority (75%) of the reports came from institutions, and the average number of appointments up to complete denture insertion was 4.1, not always including try-in dentures. In this study, it can be concluded that, with a digital workflow, the insertion appointment is reached in fewer visits than the conventional five-visit procedure which is commonly taught in dental schools.

Evaluation by 3D stereophotogrammetry of facial changes in edentulous patients after rehabilitation

OBJECTIVE

To assess facial changes after oral rehabilitation with complete dentures (CDs) by 3D technology allows understanding the results of a treatment that changes facial proportions. Precise outcome parameters can improve decision making. This descriptive observational research aimed to assess facial changes in completely edentulous patients after oral rehabilitation with a CD by a 3D stereophotogrammetry system.

METHODOLOGY

30 edentulous patients (7 men and 23 women), aged 50 to 75, were analyzed with stereophotogrammetry at 28 previously determined anthropometric landmarks, at 2 different times: T1, before treatment, and T2, after inserting the CDs. Images were analyzed with a specific software for linear and angular measurements. The paired t-test was used to compare timestamps (α=0.05).

RESULTS

Major changes were observed in 7 of the 13 linear measures and 7 of the 9 angular measures. The following linear measurements had an increase: Sn-Gn (lower third of the face), Ls-Li (height of the vermilion lip), and ChL-ChR (mouth width). Sn-Ls (nasal philtrum height) decreased. For angular measurements, Sn-St-Pg (lower facial convexity) angles increased, and the Prn-Sn-Ls (nasolabial angle) and GoR-Pg-GoL (mandible convexity) angles decreased.

CONCLUSIONS

Major facial changes in newly rehabilitated edentulous patients with CDs included an increase of the lower third of the face, of the vermilion lip, of mouth width, and of the lower facial convexity, and a decrease of the nasolabial angle and mandible convexity.

Functional Removable Prosthetic Rehabilitation Using the Electronic Condylograph: A Case Report

This article describes the design of complete removable prostheses following the Slavicek philosophy, which involves the integration between condylographic data and an individual cephalometric study of the patient. The electronic condylograph is a device that records the mandibular movements made by the patient. This case report shows how condylography data are useful not only in the individual articulator setting, but also for diagnostic completion and for planning a functional prosthetic rehabilitation.

Comparison of stresses in monoblock tilted implants and conventional angled multiunit abutment-implant connection systems in the all-on-four procedure

Background

The All-on-four dental implant method is an implantology method designed to provide a comfortable prosthetic treatment option by avoiding advanced surgical procedures. This research aims to compare and evaluate the stress and tension values in conventional angled multiunit abutment-implant connection systems and monoblock dental implants used in the all-on-four procedure with finite element analysis.

Methods

Two master models were created by placing four implants connected to multiunit abutments (group A) in the interforaminal region of a completely edentulous mandible and four monoblock implants (group B) in the same region of another completely edentulous mandible. Group A implants were classified according to their diameter as follows: 3.5 mm (M1A), 4.0 mm (M2A), and 4.5 mm (M3A). Similarly, group B implants were classified as M1B, M2B, and M3B. In the six models rehabilitated with acrylic fixed prostheses, a 100 N force was applied to the anterior implant region, and a 250 N force was applied to the posterior cantilever in both axial and 30° oblique directions. Von Mises stresses were analyzed in the bone and implant regions of all models.

Results

M1A and M1B, M2A and M2B, and M3A and M3B were compared with each other under axial and oblique forces. The maximum Von Mises stresses in the bone around implants and the prosthesis screws, and the maximum and minimum principal stresses in the cortical and trabecular bone in group A models were significantly higher than those in group B models.

Conclusions

In monoblock implant systems under axial and oblique forces, higher stress is accumulated in the bone, prosthesis screw and implant compared to multiunit abutment-implant connection systems.

Digital Workflow for Double Complete Arch Zirconia Prostheses Utilizing a Novel Scan Body

The purpose of this clinical report is to present a complete digital workflow for the fabrication of complete arch fixed zirconia implant restorations. An intraoral scanner was used to capture the implants' position at the abutment level and also the patient's existing interim prostheses with the double digital scanning technique. A novel scan body and impression pin were utilized throughout the scanning process which allowed for the accurate and reproducible superimposition of the generated Standard Tesselation Language (STL) files. Prosthesis prototypes were digitally designed and fabricated, tried in, and verified intraorally. The definitive zirconia prostheses were then fabricated and delivered to the patient. This technique can be utilized in both arches overcoming the absence of stable intraoral landmarks for superimposition of STL files.

Microstructured Hyaluronic Acid Hydrogel for Tooth Germ Bioengineering

Tooth loss has been found to adversely affect not just masticatory and speech functions, but also psychological health and quality of life. Currently, teeth replacement options include dentures, bridges, and implants. However, these artificial replacement options remain inferior to biological replacements due to their reduced efficiency, the need for replacements, and the risk of immunological rejection. To this end, there has been a heightened interest in the bioengineering of teeth in recent years. While there have been reports of successfully regenerated teeth, controlling the size and shape of bioengineered teeth remains a challenge. In this study, methacrylated hyaluronic acid (MeHA) was synthesized and microstructured in a hydrogel microwell array using soft lithography. The resulting MeHA hydrogel microwell scaffold resembles the shape of a naturally developing human tooth germ. To facilitate the epithelial-mesenchymal interactions, human adult low calcium high temperature (HaCaT) cells were seeded on the surface of the hydrogels and dental pulp stem cells (DPSCs) were encapsulated inside the hydrogels. It was found that hydrogel scaffolds were able to preserve the viability of both types of cells and they appeared to favor signaling between epithelial and mesenchymal cells, which is necessary in the promotion of cell proliferation. As such, the hydrogel scaffolds offer a promising system for the bioengineering of human tooth germs in vitro.

Four-implant-supported overdenture treatment in the maxilla. Part II: Speech- and oral health-related quality of life in patients with implant-supported overdentures in the maxilla-A prospective 3-year follow-up

BACKGROUND

Implant-supported overdentures (IOD) are becoming a more commonly used treatment in the dental practice and it risks causing speech problems.

PURPOSE

The aim of this study was investigating the changes in speech, satisfaction with speech, and overall oral health-related quality of life (OHRQoL) in edentulous patients during and after treatment with maxillary IODs.

MATERIALS AND METHODS

Twenty-one patients receiving an IOD participated in speech assessment. They were examined preoperatively with their conventional denture (CD) with full palatal coverage, after connection of the implant-bar connected denture, without palatal coverage, and 3 years thereafter. The examination included assessment of articulation in speech, OHRQoL based on total OHIP-14, and satisfaction with overall oral health and speech (visual analogue scale).

RESULTS

There was a reduction in mean number of articulation disorders from 1.00 at baseline to 0.55 at connection, although statistically insignificant (p = 0.059). Especially the /s/ sound is vulnerable. At 3 years follow-up, still 6/16 (37.5%) of the patients suffered from this speech problem. Overall satisfaction improved from 64.05/100 at baseline to 82.95/100 at connection (p = 0.008) and remained unchanged with 81.69/100 after 3 years follow-up. Patients' satisfaction with speech increased from 70.62/100 with CD to 82.63/100, 3 years follow-up (p = 0.009). Total OHIP-14 decreased from 21.45/56 with CD to 8.00/56 (p < 0.001) with IOD and 6.13/56 3 years after connection (p = 0.001). Significant improvement of all seven domains in OHRQoL was observed with IOD compared to CD.

CONCLUSIONS

Patients treated with maxillary IODs show improved OHRQoL 3 years after connection of the IOD compared to the CD. Even though patients reported improvement of satisfaction and OHRQoL, articulation disorders were still present, suggesting that patients should be informed about possible speech issues.

Efficacy of low-molecular weight chitosan against Candida albicans biofilm on polymethyl methacrylate resin

BACKGROUND

Candida biofilm is a major cause of denture stomatitis. We aimed to compare the efficacy of low-molecular-weight chitosan solutions against Candida albicans biofilm on polymethyl methacrylate (PMMA) resin.

METHODS

Various types of chitosan were tested for anti-Candida activity by broth dilution. Two types were selected for further testing on 24-hour C.albicans biofilm formed on PMMA specimens. Specimens were randomly distributed among experimental groups, including 0.1% and 0.2% acetic acid, 3 and 6 mg/mL of oligomer chitosan and 30 kDa chitosan solutions, effervescent tablet (Polident), and 0.2% chlorhexidine, and immersed for 5 min to 12 h. The viability of C. albicans after cleansing were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Remaining viability was calculated into percentage relative to respective controls and analyzed using ANOVA with Tukey post-hoc tests. Live/dead fluorescence microscopy was also performed.

RESULTS

Chitosan solutions had high efficacy against C. albicans biofilm on PMMA. The mean relative viability compared to control after 12-h immersion was 6.60 ± 4.75% and 12.72 ± 6.96% for 3 and 6 mg/mL oligomer, respectively, and 11.68 ± 4.81% and 18.08 ± 6.20% for 3 and 6 mg/mL 30 kDa chitosan, respectively.

CONCLUSIONS

Low-molecular-weight chitosan solution is an effective antifungal denture cleanser that can significantly reduce C. albicans viability in biofilm on PMMA.

3D printed complete removable dental prostheses: a narrative review

Background

The purpose of this paper is to review the available literature on three-dimensionally printed complete dentures in terms of novel biomaterials, fabrication techniques and workflow, clinical performance and patient satisfaction.

Methods

The methodology included applying a search strategy, defining inclusion and exclusion criteria, selecting studies and forming tables to summarize the results. Searches of PubMed, Scopus, and Embase databases were performed independently by two reviewers to gather literature published between 2010 and 2020.

Results

A total of 126 titles were obtained from the electronic database, and the application of exclusion criteria resulted in the identification of 21 articles pertaining to printed technology for complete dentures. Current innovations and developments in digital dentistry have successfully led to the fabrication of removable dental prostheses using CAD/CAM technologies. Milled dentures have been studied more than 3D printed ones in the currently available literature. The limited number of clinical studies, mainly case reports, suggest current indications of 3D printing in denture fabrication process to be custom tray, record bases, trial, interim or immediate dentures but not definitive prostheses fabrication. Limitations include poor esthetics and retention, inability to balance occlusion and low printer resolution.

Conclusions

Initial studies on digital dentures have shown promising short-term clinical performance, positive patient-related results and reasonable cost-effectiveness. 3D printing has potential to modernize and streamline the denture fabrication techniques, materials and workflows. However, more research is required on the existing and developing materials and printers to allow for advancement and increase its application in removable prosthodontics.

Comparison of psychometric properties of GOHAI, OHIP-14, and OHIP-EDENT as measures of oral health in complete edentulous patients aged 60 years and more

OBJECTIVES

To compare the psychometric properties of three OHRQoL indicators (GOHAI, OHIP-14, and OHIP-EDENT) in a group of complete edentulous subjects and to explore the ability of these instruments to distinguish between individuals with different prosthetic and oral health status.

METHODS

This was a cross-sectional study. Edentulous individuals aged 60 years and more were recruited between January 2019 and February 2020 in a medical and dental care centers. The Lebanese versions of GOHAI, OHIP-14, and OHIP-EDENT were used. External and internal consistencies were assessed using intraclass correlation coefficient (ICC) and Cronbach alpha, respectively. The concurrent validity was evaluated by testing the indicators against a proxy measure of a similar concept. To test their discriminative abilities, the ADD (GOHAI and OHIP) and SC (GOHAI and OHIP) scores were dichotomized according to the 25th and 75th percentile, respectively, and multivariate analyses were performed using sociodemographic, clinical, and subjective health parameters as explanatory variables.

RESULTS

Two hundred and two edentulous subjects (age: 72.94 ± 7.378 years) were included. The proportion of subjects with no impact was lower for OHIP-EDENT (7.9%) compared to GOHAI (28.2%) and OHIP-14 (38.6%). Reproducibility was satisfactory for all OHRQoL tools since they were able to reproduce the results consistently in time (ICC > 0.80). The Cronbach alpha values were greater than 0.8 indicating acceptable internal consistency. The concurrent validity of the three tools was acceptable since subjects with lower OHRQoL score were less satisfied with their dentures and reported a higher need for self-rated therapy. Concerning the discriminant validity, OHIP-EDENT was more discriminant than OHIP-14 and GOHAI, since it was more able to identify patients with poor prosthetic issues or using instable denture.

CONCLUSION

The OHIP-EDENT was more effective in identifying edentulous individuals with oral and prosthetic problems. Our results can help decide which dental instrument to use to assess the perception of oral health in edentulous individuals. More prospective studies are required to compare their evaluative properties.

Dentist-laboratory communication and quality assessment of removable prostheses in Oregon: A cross-sectional pilot study

STATEMENT OF PROBLEM

When fabricating a removable dental prosthesis, it is unclear if the information received by the dental laboratory technician is clear and sufficient.

PURPOSE

The purpose of this survey study was to evaluate the dentist's work authorizations for removable prostheses as well as determine common practices used by laboratories during the fabrication of removable prostheses.

MATERIAL AND METHODS

A 24-item questionnaire was developed based on previously published questionnaires and incorporating new topics. A public uniform resource locator (URL) survey link was generated and sent to the office of the Oregon Association of Dental Laboratories (OADL). The executive director of the board then sent out the link to 163 participants that included members and nonmembers of the OADL who were still active in the state of Oregon. Two reminder e-mails were sent 2 weeks apart. Study data were collected and managed by using the Research Electronic Data Capture (REDCap) software program. Descriptive statistics were tabulated, and responses displayed as a percentage of the total.

RESULTS

From the 163 invited participants, 26 responded to the survey representing a 15.9% response rate. Only 11% of the laboratories stated that they routinely receive work authorizations with clear instructions. All participants stated that they always (62.5%) or frequently (37.5%) design the partial prostheses frameworks. Only 37.5% of the laboratories stated that they usually receive adequately extended and accurate definitive casts to fabricate the framework. Fifty percent of the laboratories stated that they very rarely perform altered cast procedures and 50% indicated that half or more of the removable partial prostheses they fabricate were entirely made of acrylic resin. Most laboratories stated that thermoplastic resin partial dentures were less than 25% of their produced volume of removable prostheses. Only 22% of respondents stated that they usually receive adequate information to complete a denture tooth arrangement and most (78%) dentists do not routinely specify the type of occlusal scheme desired for their complete denture tooth arrangements. In most prostheses (77%), posterior palatal seal was marked by the prescribing dentists rarely or very rarely.

CONCLUSIONS

Work authorizations provided by the dentists were less than adequate and left much decision-making to the dental laboratory technician.