A randomized crossover trial assessing denture adhesive for prevention of food infiltration among partial denture wearers.

PURPOSE: This two-treatment, four-period, double-blind, randomized controlled crossover trial assessed the ability of two denture adhesives, both applied with a thin nozzle in a continuous application pattern, to prevent food infiltration beneath partial dentures. METHODS: Participants with mandibular partial dentures and a history of food particle infiltration were enrolled. All participants used both an optimized calcium/zinc partial salt of polyvinyl methyl ether/maleic acid (PVM/MA) denture adhesive and a calcium/sodium partial salt of PVM/MA test denture adhesive, twice each, throughout four study periods, according to a randomly assigned sequence. At each visit, participants underwent two assessments: once with no denture adhesive (baseline) and once with denture adhesive, 1 hour after adhesive application. For each assessment, participants ate one-half of the top of a poppy seed muffin, and a dental professional counted the seeds retained on the denture and mucosa, which was the primary variable. The change-from-baseline comparison was made for each treatment separately using a paired t-test or Wilcoxon Signed Rank test depending on the normality of the data. A between-treatment comparison for the change from baseline was performed using a crossover ANCOVA with treatment and period as fixed effects and participant as a random effect. The baseline poppy seed count was used as a covariate. RESULTS: 30 participants were enrolled; 29 completed the trial. Both denture adhesives achieved statistically significantly fewer retained seeds versus baseline (P< 0.001). The calcium/zinc adhesive reduced the seed count from baseline by 85.9% (6.18 vs 0.86), and the calcium/ sodium adhesive reduced seed count by 76.6% (6.04 vs 1.43). Comparing the two denture adhesives, the reduction in seed count from baseline was statistically significantly greater for the calcium/zinc adhesive versus the calcium/sodium formulation (P= 0.008). CLINICAL SIGNIFICANCE: These results support the recommendation of denture adhesive use for the prevention of food infiltration beneath partial dentures, with optimized calcium/zinc denture adhesive showing the greatest prevention benefit.

Accuracy and surface roughness of Co-Cr partial denture frameworks with different digital fabrication methods.

STATEMENT OF PROBLEM: Traditional removable partial denture (RPD) manufacture is being phased out in favor of computer-aided design and computer-aided manufacturing (CAD-CAM) techniques and rapid prototyping (RP), which provide more efficient methods of producing RPD frameworks. However, studies comparing the accuracy and surface roughness of these approaches on RPD frameworks are still scarce. PURPOSE: The purpose of this in vitro study was to evaluate the accuracy and surface roughness of class I cobalt chromium (Co-Cr) removable partial denture frameworks digitally constructed using 2 different CAD-CAM technologies: direct milling (DM) and selective laser melting (SLM). MATERIAL AND METHODS: An educational maxillary stone cast was scanned to create a resin model after rest seat preparation. The resin model was scanned, and an RPD framework was digitally designed. Sixteen frameworks were constructed (n=8). Two groups were defined. In the direct milling (DM) group, the standard tessellation language (STL) file of the RPD framework was used to mill the design from a Co-Cr blank directly. In the selective laser melting (SLM) group, the STL file of the RPD framework was used to print the design from Co-Cr powder using the selective laser melting technique. Geomagic Control X software program was used to measure the accuracy of the fabricated frameworks. Surface roughness was tested using optical profilometry. An unpaired t test was used to compare the 2 groups (α=.05). RESULTS: The DM group showed significantly higher mean ±standard deviation accuracy (189 ±9 µm) (P<.001) compared with the SLM group (456 ±122 µm). Regarding the surface roughness, the DM group (0.157 ±0.001 mm) showed significantly lower surface roughness (P<.001) compared with the SLM group (0.256 ±0.001 mm). CONCLUSIONS: The direct milling fabrication technique enabled the fabrication of Co-Cr RPD frameworks with higher accuracy and less surface roughness when compared with the 3-dimensionally printed SLM technique.

Evaluation and assessment of the wettabilty and water contact angle of modified poly methyl methacrylate denture base materials against PEEK in cast partial denture framework: an in vitro study.

INTRODUCTION: The prevalence of adults with partially dental arches is expected to be more than imagined and patients requiring replacement of missing teeth are slowly increasing in number too. Removable partial dentures are known to provide for substantial replacement for the missing teeth with also added advantages when compared to fixed or implant prosthesis, mainly in elderly patients. Denture base material performance and durability are greatly influenced by wettability and water contact angle. In the case of dentures; adequate moisture distribution is necessary to ensure excellent wettability which has an influence on comfort and oral health. The purpose of conducting this study was to find out whether the advancements made using PEEK (Polyether ether ketone) would prove to be more beneficial than the current upgrades in the current material spectrum. MATERIALS AND METHODS: This study was performed under in vitro conditions. All the fabrication and processing was done only by one operator. The materials used were divided into three groups each comprising 20 samples. Group A was modified polymethylmethacrylate (Bredent Polyan), Group B was polyoxymethylene acetal resin (Biodentaplast) and Group C was PEEK. An Ossila Goniometer was used to measure the contact angle. The three types of liquids used for the testing included distilled water, natural saliva and mouth wetting solution (Wet Mouth Liquid, ICPA India). Human saliva was collected from an individual with no medical conditions and normal salivary secretion. RESULTS: The data was analyzed using One-way ANOVA test and a pairwise comparison using the Post Hoc Tukey's Honest Significant Difference. Table 1 consists of the mean water contact angles of the denture base materials and mean contact angles of various denture base materials. In saliva, mouth wetting solution and distilled water, the highest mean and least mean contact angle was seen in Polyan and Biodentaplast respectively. A signicant difference was seen between PEEK and Polyan and Biodentaplast and Polyan on further comparison. CONCLUSION: From the resources and the materials at our disposal, it could be concluded that Polyan, Biodentaplast and PEEK and could be used as viable options in cast partial denture framework.

[Brief Analysis of Clinical Evaluation Concerns of Personalized Abutments and Abutment Crown Bridge Products].

Objective: The applications of personalized abutments and abutment crown bridge products have increased year by year, but there is no clear requirement for clinical evaluation of the same variety of such products. This study mainly introduces the clinical evaluation concerns of personalized abutments and abutment crown bridge products, in order to provide reference for the declaration and registration of such products. Methods: The clinical evaluation of personalized abutments and crown bridge products are summarized, and the research content of clinical evaluation is clarified. Results: The clinical evaluation requirements that need to be considered by enterprises are introduced. Conclusion: Personalized abutment and abutment crown bridge products can refer to this study when they are launched in China, mainly using in vitro performance comparison tests for equivalence verification.

Japanese Wooden Plate Denture as Origin of Suction Retention.

The modern theory of complete denture retention using suction was applied to wooden plate dentures in Japan from the first half of the 16th century, which is an astonishing achievement since it was clinically applied in North America and Europe in the latter half of the 19th century nearly 300 years later. Wooden dentures are unique to Japan resulting from skilled Japanese craftsmanship and are not found in other countries. We comprehensively reviewed reports on wooden plate dentures, analyzed 145 complete and partial dentures, and discussed their history. Japanese wooden plate dentures are mainly made of box wood, and artificial teeth are made of pagodite, ivory, and natural teeth. Small nails were driven into the molar region. Many existing dentures revealed attrition on the occlusal faces, thereby indicating that the wearers were able to masticate sufficiently. Wooden plate dentures have been used for 400 years in the early 20th century. Although Japanese wooden dentures have not been mentioned in the history of dentistry in Western literature, they comprise an important part of the history of denture development.

Performance of complete dentures fabricated with the simplified and the traditional technique: A randomized clinical trial.

STATEMENT OF PROBLEM: The simplified technique has been recommended for the fabrication of removable complete dentures. However, a consensus regarding the performance of the simplified and the traditional techniques is lacking. PURPOSE: The purpose of this randomized clinical trial was to compare the performance of prostheses fabricated with the simplified and the traditional techniques. MATERIAL AND METHODS: Sixty participants were recruited and randomized into 2 groups: traditional technique (control group) and simplified technique (experimental group). The assessments were performed before treatment (baseline) and 2 and 4 months after adaptation to the new complete dentures. The variables evaluated were satisfaction, oral health-related quality of life (OHRQoL) by using the Brazilian version of the OHIP-EDENT, the quality of the prostheses, and, for the functional assessment, the masticatory performance and swallowing threshold. The data were analyzed by the Fisher exact test, the Mann-Whitney test, and the generalized equations estimating (GEE) method. RESULTS: At baseline, the mean ±standard deviation quality of the prostheses was 5.3 ±2.3 for the traditional technique and 4.9 ±2.3 for the simplified technique, and at 4 months, it was 9.3 ±0.9 and 9.1 ±0.9, respectively. For masticatory performance, the mean ±standard deviation X50 at baseline was 5.7 ±1.4 for the traditional technique and 5.7 ±0.9 for the simplified technique, and at 4 months, it was 3.8 ±1.2 and 3.7 ±0.9, respectively. The mean ±standard deviation OHRQoL at baseline was 14.1 ±8.6 for the traditional technique and 12.5 ±9.4 for the simplified technique, and at 4 months, it was 3.2 ±4.3 and 2.6 ±5.1, respectively. The mean ±standard deviation satisfaction at baseline was 9.5 ±3.9 for the traditional technique and 9.3 ±4.2 for the simplified technique; after 4 months, it was 14.8 ±2.0 for both techniques. There was a significant improvement (P<.05) for all variables in the study when comparing them at the baseline to those at the evaluation after provision of new complete dentures. There was no significant difference in all analyzed variables (P>.05) between the 2 techniques for prosthesis fabrication. CONCLUSIONS: The simplified technique appears to be a suitable alternative to the traditional technique for the fabrication of complete dentures, with similar performance.

Use of zirconia onlays in a maxillary removable implant-supported denture: A clinical report.

A common complication with the use of acrylic resin denture teeth is wear of the occlusal surfaces. Modifying the occlusal surfaces with gold onlays has been suggested to combat this phenomenon. This clinical report describes the use of zirconia as an alternative material on a patient with increased tendencies for occlusal wear. The advantages of using zirconia include wear resistance, decreased cost, and straightforward fabrication.

Viral contamination of acrylic resin removable denture bases in patients with COVID-19: A cross-sectional study.

STATEMENT OF PROBLEM: Salivary gland ducts are one of the primary targets of severe acute respiratory syndrome coronavirus 2. Moreover, saliva contains minor and major salivary gland secretions and a combination of nasopharyngeal and lung secretions. The acrylic resin bases of complete or partial removable dentures have pores and provide a favorable environment for the growth of microorganisms. PURPOSE: The purpose of this cross-sectional study was to investigate the presence of viral contamination of acrylic resin removable denture bases in patients with coronavirus disease 2019 (COVID-19). MATERIAL AND METHODS: The acrylic resin denture bases (partial and complete) of 29 patients with COVID-19 who underwent treatment in the Infectious Diseases Department of Razi Hospital in Ghaemshahr, Mazandaran, Iran, were evaluated. Samples were collected from the intaglio surface of the prostheses by direct swabbing and coding and were evaluated in a laboratory for the presence or absence of coronavirus. The relationship between hospital polymerase chain reaction (PCR) and denture PCR and the relationship between denture type and denture PCR were evaluated with the Fisher exact test (α=.05). RESULTS: Twenty-nine patients, age range 55 to 85 years, 18 women, 3 with partial dentures and 26 with complete dentures, were evaluated. The hospital PCR test was positive in 28 patients, while the denture PCR test was positive in 4 patients. No significant relationship was observed between the results of hospital PCR and denture PCR in patients with COVID-19 (P=.138). All 4 patients who tested positive for denture PCR had complete dentures. No significant relationship was found between denture type and denture PCR test results in patients with COVID-19 (P>999). CONCLUSIONS: Despite the microporous structure of the acrylic resin base, no statistically significant viral contamination was observed.

[Protocol for teeth set-up in full denture without the use of wax rims and its theoretical justification]. / Protokol postanovki iskusstvennykh zubov bez ispol'zovaniya prikusnykh valikov i ego teoreticheskoe obosnovanie.

OBJECTIVE: To develop a protocol for setting artificial teeth in a complete removable denture without landmarks on the bite ridges. MATERIAL AND METHODS: Based on the analysis of the literature of various areas of dentistry and the clinical experience of doctors corresponding to each of the disciplines of the specialty, a protocol for setting teeth in a full prosthesis was developed and its theoretical justification was given. RESULTS: Using the method proposed by us, 324 prostheses were made for 162 patients with complete secondary adentia of two jaws. A clinical study and comparison with the generally accepted method of manufacturing prostheses using wax rollers was carried out. The method proposed by us showed greater efficiency based on a comparison of the results of functional tests after prosthetics. CONCLUSION: The described method is part of the concept of manufacturing a functional prosthesis, is used in removable prosthetics, but can also be used in non-removable prosthetics, allows highly accurate, in accordance with individual anatomical parameters and features, to restore the occlusion of the patient during the reconstruction of the dentition, taking into account individual anatomical and functional parameters.

Sociomedical and oral factors affecting masticatory performance in an older population.

OBJECTIVES: To assess the sociomedical and oral factors affecting masticatory performance in a community-dwelling older population. MATERIALS AND METHODS: Community-dwelling persons over 60 years were investigated using medical and dental oral interviews, oral and denture examination (natural teeth, tooth mobility, number of occluding tooth pairs, and removable dentures' prevalence and quality), and evaluation of masticatory performance using a mixing ability test. RESULTS: A total of 130 participants with a mean age of 73.9±8.5 years were recorded. Fifty-eight (44.6%) used various types of removable prostheses. Twenty were edentulous and used a pair of complete dentures. Univariate analyses revealed statistically significant associations (p≤0.05) between masticatory performance and aging, marital status, subjective chewing ability, use of removable dentures, use of various combinations of complete dentures, pain caused by maxillary denture, number of teeth, tooth mobility, posterior chewing pairs, all chewing contacts natural or prosthetic, retention of mandibular partial dentures, and dentures' occlusion. The multivariable quantile regression analysis revealed that fewer natural teeth (95% CI: -0.02-0.01, p<0.001), being edentulous and using a pair of complete dentures (95% CI: 0.09-0.35, p=0.001), and larger percentage of severely mobile teeth (95% CI: 0.07-0.82, p=0.020) were associated with lower masticatory performance. CONCLUSIONS: Poor masticatory performance in older adults was associated with fewer teeth, being edentulous and using a pair of complete dentures, and increased prevalence of severe tooth mobility. CLINICAL RELEVANCE: Retaining the natural dentition and preventing and treating periodontal disease are important measures to maintain masticatory performance in older adults.

Innovative subtractive production of a digital removable complete denture from start to finish: a JPD Digital video presentation.

This JPD Digital video presentation presents the clinical treatment from start to finish in which a dual-shaded bi-coloured monolithic disk was used for the fabrication of an immediate digital complete denture followed by the delivery of a definitive digital complete denture. The treatment plan included extraction of the remaining maxillary and mandibular teeth followed by an esthetic evaluation with digital smile design. The digital definitive complete dentures were milled from a monolithic dual-shaded disk.

Impact of rehabilitation with removable complete or partial dentures on masticatory efficiency and quality of life: A cross-sectional mapping study.

STATEMENT OF PROBLEM: Tooth loss directly affects mastication, cognitive function, and oral health-related quality of life (OHRQoL). Complete dentures (CDs) and removable partial dentures (RPDs) represent a common oral rehabilitation approach. However, studies addressing the impact of removable dentures on replacing missing teeth are lacking. PURPOSE: The purpose of this clinical study was to evaluate whether the OHRQoL, the jaw function limitation (JFL), and the masticatory efficiency of CD and RPD wearers are similar to those of patients with natural teeth and to evaluate whether wearing removable dentures can predict an effect on the OHRQoL, JFL, and masticatory efficiency of their wearers. MATERIAL AND METHODS: The Oral Health Impact Profile (OHIP-14) questionnaire and the JFL scale were used to measure OHRQoL and JFL. Masticatory efficiency was analyzed by using a subjective color-mixing index for the chewing gum bolus and shape index and an objective colorimetric analysis by using a software program ViewGum. Data were analyzed with Kruskal-Wallis and post hoc Dunn tests, followed by multiple linear regression (α=.05). RESULTS: The results from OHIP-14 evidenced that both denture groups presented a low impact on OHRQoL. JFL was higher for all denture wearers. For the subjective color-mixing analysis, the control and RPD groups presented better masticatory efficiency than CD wearers. Colorimetric analysis evidenced better masticatory efficiency for the control group, who differed from the CD and RPD groups. Wearing RPDs was a predictor of impaired JFL and OHRQoL, and the use of CDs was a predictor of impaired JFL and masticatory efficiency. CONCLUSIONS: Despite being rehabilitated, CD and RPD wearers still had impaired OHRQoL, JFL, and masticatory efficiency. Also, the use of these prostheses can predict a negative effect on these 3 variables.

[Automated digital superimposition of the 3D model and archival photographs of full removable dentures in forensic dentistry]. / Avtomatizirovannoe tsifrovoe issledovanie v sudebno-stomatologicheskoi ekspertize dlya sopostavleniya ob"emnoi modeli i arkhivnykh fotografii polnykh s"emnykh protezov.

THE AIM THE STUDY: The purpose of the work is to perform automated alignment of two-dimensional archival photographs of the first prosthesis and a digital model of the complete removable prosthesis by superposition in order to determine or deny their possible belonging to one user. MATERIALS END METHODS: The superposition was carried out in the Exocad program (DentalCAD 3.0 Galway) using the standard 2D-3D alignment algorithm of the «SmileDesign¼ module; in the same program. In addition, Keynote and Fusion 360, and Autodesk programs were used. Statistical measurements were carried out at the statistically significant level of p<0.05. RESULTS: A comparison of four different-angle and different-scale photographic images of a removable denture of the upper jaw teeth with a three-dimensional copy of the same version of the prosthesis of the life physician of the royal family E.S. Botkin was made. When superimposing a digital three-dimensional model and a two-dimensional photograph of the original prosthesis with marked anthropometric points (n=51), 21 of them coincided or touched each other (41.2%). Another 26 points were located side by side (distance up to 1.5 mm) (50.9%) and 4 did not coincide (distance >1.5 mm, but no more than 3.5-4 mm) (7.8%). When the reference points were combined, the contours, the configuration of the relief and the peripheral boundaries of all three objects mostly coincided. The linear longitudinal and transverse dimensions of the bases of the prostheses also mostly coincided. The exception was the distal border of the bases, and the level of the cutting edges of the anterior artificial teeth, where complete coincidence was not observed, due to differences in the degree of erasability. CONCLUSION: Comparison of the original prosthesis from Ipatiev's house and its stereolithographic model was a test for the accuracy of the matching method used. The stereotype of the compared images is proved and the consistency of the possibility of computer combination of three-dimensional and two-dimensional objects is confirmed. The use of traditional methods of forensic identification and evaluation of the results by methods of mathematical statistics allowed us to conclude that the two different complete removable dentures of the upper jaw depicted in the photographs belong to one user.

[Evaluation of the operational properties and effectiveness of the use of specialized adhesive agents for fixing removable dentures in re-prosthetic patients]. / Otsenka ekspluatatsionnykh svoistv s"emnykh zubnykh protezov i effektivnosti ispol'zovaniya spetsializirovannykh adgezivnykh sredstv dlya ikh fiksatsii u povtorno proteziruemykh patsientov.

OBJECTIVE: The questionnaire survey of different age groups using partial and full removable dentures to assess the operational properties and effectiveness of the use of specialized adhesives for removable dentures. MATERIAL AND METHODS: The study comprised 228 patients (70 men and 158 women, in the age groups 35-44, 45-54, 55-64 and over 65 years). All of them had previously used partial or full removable dentures, and they applied again to replace the denture or appeared for a follow-up examination. RESULTS: At the time of the survey, 130 (57%) of the respondents used specialized adhesive agents for prostheses fixing. Among those 130 patients, 75.3% of patients noted that they use «Corega¼, cream that indirectly indicates its good consumer characteristics; other compositions: Blend-a-Dent, President, Protefix - were named by 2.2%, 4.6% and 17.9% of respondents, respectively. The largest number of respondents - 124 (95.3%) - noted an improvement in the chewing function, improved speech was indicated by 64 (49.2%) patients, a decrease in food accumulation under the prosthesis by 92 (71%) patients. In general, 66 (50.8%) respondents using specialized fixing agents stated the improvement in the quality of life. CONCLUSION: The results of the research indicate the need for receiving feedback from patients, and this is an objective criterion that allows us to evaluate not only the characteristics of the product declared by the manufacturer, but also the orthopedic dentist's work on information the patients about the modern treatment approach to partial and full teeth loss management.

[The effect of astaxanthin on the adaptation of the oral mucosa to a removable denture]. / Vliyanie astaksantina na adaptatsiyu slizistoi obolochki rta k s"emnomu protezu.

THE AIM: Of this study was the evaluation of the effect of the antioxidant gel on the oral mucosa and reduction of the time of adaptation to a removable denture in patients with partial adentia. MATERIAL AND METHODS: The study comprised 105 patients aged 30-65 years divided into three groups: the main group of 45 patients, the comparison group of 35 patients, the control group of 25 patients. The main group was given a prophylactic gel with natural astaxanthin after the delivery of a removable prosthesis. The patients of the control group and the comparison group do not received an antioxidant gel. Patients of all three groups underwent a study of the hygienic state of the oral mucosa and oral fluid to assess the state of oral microbiocenosis. The main group and the comparison group underwent visual examination and photoplanimetric control after the placement of a removable denture. RESULTS: A positive preventive and anti-inflammatory effect of astaxanthin gel was found in patients who received an immediate and a partial removable dentures. The use of the gel for 7 days helps to reduce the values of hygiene indices, concentrations of bacterial plasmalogen and endotoxin in the oral fluid in the short-term perspective. CONCLUSION: Preventive dental gel with astaxanthin decreases the time of adaptation to removable dentures by 1.7-2 times and reduces the risk of prosthetic stomatitis due to its wound-healing, anti-inflammatory and antimicrobial actions.

Modification of denture teeth for improved occlusal stability of a maxillary removable complete denture opposed by a mandibular implant-supported fixed complete denture: A clinical report.

Wear of artificial teeth is the most common complication associated with an implant-supported fixed complete denture (ISFCD). This wear alters the occlusal scheme, with loss of eccentric occlusal balance and vertical dimension of occlusion (VDO). This clinical report describes the fabrication of a new maxillary removable complete denture opposing an existing ISFCD with occlusal modifications. Both prostheses received splinted zirconia crowns cemented with composite resin cement.

Validity and reliability of new instruments for measuring patient satisfaction with removable dentures, Arabic Version.

BACKGROUND: The psychometric properties of self-administered instruments for measuring patient satisfaction with removable dentures should be tested before inviting patients to express their opinions. This study aimed to evaluate the validity and reliability of new instruments in the Arabic language that measure patient satisfaction with all types of removable dentures. METHODS: A three-step methodology was used to translate and test the instruments. In step one, the instruments were translated from tested German instruments to develop the pilot questionnaires. In step two, the face validity of the pilot questionnaires was tested through three rounds of interviews. There were 15, 13, and 15 participants per round, respectively. At the end of every round, the results of the interviews were discussed with an expert panel. The expert panel confirmed the form and the type of questionnaires' adjustments before a new round of interviews began. At the end of step two, the final form of the questionnaires was reached. In step three, 235 questionnaires were distributed to 133 participants to estimate the construct validity of the upper jaw and the lower jaw questionnaires. After one week, the participants were asked to complete the questionnaires again. A total of 102 questionnaires were returned and used to assess the instruments' reliability. Factor analysis was used to assess the construct validity. The intraclass correlation coefficient and Cronbach's alpha were used to estimate the reliability and suitability of the items in the indexes. RESULTS: The result of step one was two pilot questionnaires. The pilot questionnaires were adjusted in step two. At the end of step two, the questionnaires proved to have good face validity. Factor analyses in step three revealed that only one factor could be retained. The one-factor model explained 60.95% and 63.06 of the total variance of the upper jaw and lower jaw questionnaires, respectively. The items in every questionnaire shared the same cluster and could be summed to form an upper jaw index and lower jaw index that reflected patient satisfaction with removable dentures. Cronbach's alpha values indicated excellent internal consistency and reliability for the upper jaw questionnaire (α = 0.91) and the lower jaw questionnaire (α = 0.92). Intraclass correlation coefficient values ranged from 0.72 to 0.95, which can be considered "moderate" to "excellent". CONCLUSIONS: The Arabic version of questionnaires and indexes assessing patient satisfaction with upper and lower removable dentures are reliable and valid self-administered instruments.

In vitro performance of CAD/CAM and conventional removable dentures.

AIM: Innovations in CAD/CAM technology and materials science offer new methodologies for removable prosthodontics. As clinical data are still rare, in vitro performance of both CAD/CAM and comparable conventional materials may help to estimate the clinical outcome. MATERIALS AND METHODS: Specimens (n = 8 per group) from teeth (CediTEC, SR VivodentCAD, Vitapan), base materials (V-Print dentbase, IvoBase CAD, Paladur), adhesives (CediTEC Primer/Adhesive, IvoBase CAD Bond), and a fully printed specimen (Try-In) were created. All specimens underwent thermal cycling and mechanical loading (TCML): 1,200,000 × 50 N; 2x3000 x 5°C/55°C; H2O. Surviving specimens were loaded to fracture. Statistical tests used were the Shapiro-Wilk test and the Kaplan-Meier survival, with the level of significance set to α = 0.05. RESULTS: Mean loading cycles until failure varied between 100 and 621,667 cycles. Up to five specimens per group failed during TCML. With one exception, all specimens of the entirely CAD/CAM-fabricated group survived TCML. The log-rank (Mantel-Cox) test showed significantly different (P = 0.000) loading cycles between the systems (chi-square test: 28,247; degree of freedom: 8). Failure of the dentures during TCML was characterized by failure of the denture base (2x), denture tooth (13x), mixed base/tooth (3x) or adhesive between base and tooth (1x). CONCLUSION: TCML and fracture testing showed different aspects of denture tooth restoration. The results indicated no correlation between fracture force, fracture pattern, and survival cycles. Denture teeth (milled, heat-pressed), bases (milled, printed, pressed), and primer should be matched up to optimize the performance of dentures.

Digitally Fabricated Removable Complete Denture Clinical Workflows using Additive Manufacturing Techniques.

The use of computer aided design and computer aided manufacturing in the fabrication of complete removable dentures has demonstrated that the prostheses produced are superior in many ways to removable dentures produced using analog techniques. A variety of clinical workflows that take advantage of digital technology have been shown to shorten the number of appointments required to produce high quality prostheses. This paper presents an overview of additive manufacturing in contemporary removable complete denture workflows and describes effective three appointment clinical techniques using additive manufacturing to produce a clinical trial denture and definitive prosthesis.

Does oral dryness influence pressure pain sensitivity in the oral mucosa of removable denture wearers?

OBJECTIVE: This study aimed to determine if oral dryness is associated with oral pain sensitivity in removable denture wearers. MATERIALS AND METHODS: The pressure pain threshold (PPT) in the mucosa at the midline between the central incisors in the maxilla and mandible was evaluated in 333 removable denture wearers (mean age 71.2 years, male 33.3%). The frequency of oral dryness and severity of anxiety were evaluated using self-reported questionnaires. Multilevel analyses considering the correlated data structure (jaws nested within individual) adjusted for age, sex, number of missing teeth, anxiety level, smoking status, and systemic diseases were performed to examine the association between PPT and oral dryness. Further subgroup analysis stratified by number of missing teeth was performed. RESULTS: Oral dryness was present in 122 (21.6%) of 566 jaws in 73 (21.9%) of the 333 subjects. The mean (standard deviation) of the log PPT was 2.00 (0.26) in the subjects who perceived oral dryness and 2.04 (0.22) in those who did not. Oral dryness was associated with a lower log PPT, but the relationship was not significant (coefficient - 0.017; 95% confidence interval - 0.071, 0.038). Subjects with oral dryness and edentulous oral mucosa had a significantly lower PPT (coefficient - 0.145; 95% confidence interval - 0.283, - 0.006) than their partially dentate counterparts. CONCLUSION: There was a significant association of oral dryness with increased pressure pain sensitivity in the oral mucosa only in jaws with complete dentures. CLINICAL RELEVANCE: The approach to oral dryness could contribute to reduction of oral pain sensitivity.