The International journal of prosthodontics最新文献

Purpose: To compare the influence of 0, 45 and 90 degrees build direction on fracture load and surface roughness of additively manufactured three-unit fixed provisional restoration, and to compare with provisionals fabricated using conventional materials.

Material and methods: Mandibular typodont right second molar and premolar were prepared for missing mandibular first molar to receive three-unit fixed partial denture. Six groups of 10 samples each, 3-unit provisionals were fabricated using additional manufacturing at 0,45 and 90 degrees, heat polymerized polymethyl methacrylate, auto polymerizing resin and bis-acryl composites resins and tested for fracture load and surface roughness. One way ANOVA and Tukey tests were used to analyze the data.

Results: For fracture load, lowest mean value was obtained for auto polymerizing bis-acrylic resin (464.9N) and highest value for 0 degree (596 N), while surface roughness values were lowest for heat polymerized polymethyl methacrylate (0.132μm), and the highest for auto polymerizing polymethyl methacrylate (0.836 μm). Significant differences were obtained between three build directions for fracture load and surface roughness (p=0.001); in all pairwise comparisons except between 0 and 90 degrees (p=0.502) for fracture load; and between all three build directions for surface roughness (p=0.01). On comparing with other provisional materials, significant difference (p=0.001) was observed between all groups. Conclusion- Build direction affected the mechanical properties of additively manufactured three-unit provisionals with 0 degree printed provisionals showing highest fracture load and lowest surface roughness. On comparing with other provisional materials, 0 degree showed highest fracture load, with surface roughness similar to heat polymerized provisionals.

As implant-supported restorations have become very popular, there is a tendency to extract teeth and replace them with implants. However, the first goal of dentistry should always be the preservation of natural teeth, given the prerequisite that these can be maintained with the application of appropriate treatment modalities. Therefore, individual tooth risk assessment and prognosis are very important in the treatment plan process. Four important factors influencing the dentist's decision on whether to save or extract a compromised tooth have been identified, and an extensive search of the related English language literature has been performed. Additionally, hand-search in related journals was implemented, and classical textbooks were consulted. Identified articles on patient-related, periodontal, endodontic, and restorative factors were thoroughly analyzed, focusing on diagnosis and tooth prognosis. Fifty-two selected references have been carefully selected and reviewed. Available information was used to develop a color-coded prognostic decision chart with four different factors and up to fourteen crucial parameters. All factors and parameters were analyzed in an effort to help the restorative dentist make a prognostic decision. The proposed color-coded prognostic decision chart can be helpful when a treatment plan is made, and predictable restorative care is planned. This comprehensive prognostic decision chart can aid dentists in providing clinical care of high quality and establishing a consensus on available restorative options. It can additionally establish appropriate communication with patients and third-party individuals in the restorative care process, effectively manage risk factors, and provide a framework for quality assessment in restorative treatment.

Objective: To investigate the effect of digital scanning combined with reverse engineering technology in the demonstration of full crown tooth preparation.

Methods: Thirty-one students were randomly divided into the two groups. The students in the control group carried out traditional demonstration by the use of eye-measurement methods. The students in the experimental group carried out improved demonstration by the use of digital intraoral scan with 3D measurement data. The students in both groups were provided with two resin teeth to conduct full crown tooth preparation on head model dental simulators. The teeth prepared before and after demonstration were scored by Chinese Stomatological Association Group Standards, with a total score of 100 points. Analysis of covariance was performed to comparatively analyze the scores related to the tooth surfaces, and convergence angle between two groups.

Results: Analysis of two prepared teeth (tooth #11 and #16) in two groups showed that there was a statistical significant difference in the mean score between the control group and experimental group (tooth #11, P = 0.0039) (tooth #16, P = 0.0120).The demonstration of the tooth #16 showed that there were statistical significant differences in the scores related to buccolingual surface (P = 0.0205) and proximal surface (P = 0.0023) between the control group and experimental group; There was a statistical significant difference in the score related to the convergence angle of buccolingual surface between the control group and experimental group (P = 0.0265).

Conclusion: The digital methods can effectively improve the quality of tooth preparations and has a pedagogical advantage for posterior teeth, which present greater operational challenges.

Purpose: To determine whether digital training improves conceptual skills acquisition for custom tray fabrication and tooth arrangement in the preclinical curriculum for complete denture fabrication.

Materials and methods: A crossover design study compared third-year student grades after conventional (manual) and digital training. Half the students were trained with conventional techniques prior to digital, while the other half were trained with digital techniques prior to conventional. The first part of the study (DP1) focused on custom tray fabrication and involved 154 students. The second part (DP2) focused on tooth arrangement with 204 students. The effect of preliminary digital training on conceptual skills was assessed by comparing the results of the students using a Student's t-test. Results were also analyzed by ranking on the students' Perceptual Ability Test (PAT) score. Finally, students' satisfaction with the training was investigated.

Results: Students who completed the initial digital session achieved better custom tray fabrication and tooth arrangement in the subsequent manual sessions. For manual laboratory work, the most dexterous students (PAT1 group) demonstrated the best performance. However, PAT2 students had the best performance during the digital sessions during DP1, and PAT1 and PAT2 students had the best performance during the digital sessions during DP2. Additionally, 40% of DP1 and 12% of DP2 students expressed satisfaction with digital sessions.

Conclusion: With complementary manual and digital teaching, digital tools may be useful for enhanced student learning. Digital training has contributed to improve results in manual sessions but did not affect student satisfaction and remained a limited tool to detect learning difficulties.

Aims: The aim of this prospective study was to evaluate and compare the implant survival rate, marginal bone levels and prostheses failure rate, of three-unit fixed dental prostheses (FDPs) supported by three vs. two implants immediately loaded in the posterior area.

Material and methods: Partially edentulous patients in need of a three-unit implant supported FDP in the maxillary/mandibular posterior region were recruited and randomly split into two groups: Group 1 with three-unit FDP supported by three implants (Control); Group 2 with three-unit FDP supported by two implants (Test). Implants were inserted and immediately loaded with a temporary FDP.

Results: Sixty-three patients were included in the study. A total of 178 implants were placed and immediately loaded (128 maxillary/50 mandibular) to support 74 immediate provisional fixed prostheses (52 maxillary and 22 mandibular) delivered on the same day of implant insertion/placement; 30 in Group 1 and 44 in Group 2. The comparison of three vs. two implants resulted in comparable implant survival rate, marginal bone loss, and prostheses failure rate. All implants healed uneventfully with no adverse clinical and radiographical signs or symptoms except for one implant failure in Group 1 resulting in a cumulative success rate of 99,5%, 98,9% for Group 1 and 100% for Group 2 with a follow-up of 6-to-10 (mean 7 years). Once loaded, the implants remained in function from a minimum of 6 years to 10 years.

Conclusions: Although more studies and larger sample sizes are needed to validate this study, the results showed no difference between the two Groups, demonstrating the potential viability of both clinical options.

Objective: To investigate the prosthetic parameters, clinical indices, crestal bone levels, and inflammatory biomarkers in peri-implant crevicular fluid as influenced by two different implant restorative materials i.e., metal ceramic and monolithic zirconia at baseline, 1 Year and 2 Years.

Materials and methods: Twenty patients with bilateral implants placed in the same arch were selected. Monolithic zirconia (4Y-PSZ) crown was placed on one side whereas a metal ceramic (M C) crown was inserted on the contralateral side after randomization. Interproximal marginal bone level (MBL), clinical parameters, MMP-8 levels in PICF, and prosthetic characteristics (as determined by modified USPHS criteria) were evaluated at baseline, 1-year, and 2-year follow-ups. Data were descriptively examined. The results were evaluated using the Chi-Square Test, ANOVA, and student t-test. At p < .05., statistical significance was determined.

Results: Twenty MC crowns and twenty Mono-ZrO2 crowns were delivered. A 100% survival of the implants and the prosthetic crowns was achieved across all patients with no instances of failure noted throughout the two-year follow-up period. The periodontal changes observed in the participants were analysed and demonstrated statistically insignificant alterations. Prosthetic alterations were assessed according to USPHS criteria, revealing minor ceramic chippings and instances of screw loosening within the MC group during both the 1- and 2-year follow-up periods. These incidents were collectively categorized as technical issues. Regarding anatomical form and color match to the surrounding dentition, the Mono- ZrO2 crowns obtained much lower evaluations when compared to the M-C crowns. However, when evaluating the loss of marginal bone and level of inflammatory markers there were no discernible variations between the groups.

Conclusions: The null hypothesis that there is no similarity in the survival rates and interactions at the peri-implant interface between the two types of restorations was rejected. Both monolithic zirconia and metal ceramic crowns demonstrated no statistical differences across all parameters examined in the present prospective investigation.

Purpose This study evaluated the color alterations, flexural strength and microhardness properties of two different 3D-printed permanent crown resins. Materials and Methods Samples were produced from two different 3D Print permanent crown resins: Group 1 (Saremco Crowntec; Saremco, Switzerland), Group 2 (P-crown Version 2; Senertek, Turkey). Color changes (ΔE values), flexural strenght and vickers hardness number of the samples were calculated. Data were analyzed with Shapiro-Wilk normality test, Independent-t test, and Mann Whitney-U tests. Significance level was accepted as P<0.05. Results ΔE values for red wine were found to be significantly higher in Group 1 (6.43Å}2.26; P<0.001). The flexural strength values (MPa) of Group 1 were significantly higher than Group 2 in all three solutions (P<0.001). There was no significant difference between the VHN values of the samples kept in wine and coffee solutions (P= 0.271; 0.827). Conclusion 3D printing resins are affected at different levels by coloring solutions. Microhardness and flexural strength of 3D print samples kept in different coloring agents are different.In the use of 3D printing resins, product selection should be made by taking into account the individual factors such as the eating and drinking habits of the patients and the physical properties expected from the sample.

Effect of model resin and shaft taper angle on the trueness and fit of additively manufactured removable dies in narrow ridge casts Purpose. To evaluate how model resin and shaft taper affect the trueness and fit of additively manufactured removable dies in narrow ridge casts.

Material and methods: A typodont model with a prepared mandibular molar was scanned to design virtual dies with different shaft tapers (0-degree (straight), 5-degree, and 10-degree tapered). Fifteen dies and one hollowed cast per taper were additively manufactured from two resins (G-PRINT 3D Model, GP and DentaMODEL, DM). Dies and casts were digitized to evaluate their trueness (root mean square (RMS)). The fit of the dies was evaluated with crown portion's RMS when seated in the cast and with distance deviations. Kruskal-Wallis and Mann-Whitney U tests were used to analyze data (α =.05).

Results: GP dies had lower overall, root, and base RMS, while DM dies had lower crown RMS (P≤.016). Straight dies had the highest overall, root, and base RMS within GP (P≤.030). Ten-degree dies had the lowest overall and base RMS, lower crown RMS than straight, and lower root RMS than 5-degree dies within DM (P≤.047). When the dies were seated, GP had lower crown portion RMS within 5- and 10-degree dies, and 5-degree dies had the highest RMS within DM (P≤.003). GP had lower distance deviations within 5- and 10-degree dies. Five-degree dies had the highest deviations within DM (P≤.049).

Conclusions: GP dies mostly had higher trueness and better fit. Straight dies mostly had lower trueness within GP. Ten-degree taper mostly led to higher trueness within DM. The shaft taper affected DM dies' fit.

Objective: Evaluate the roughness and color stability of different types of resins used to immerse denture bases in various denture cleansers overnight.

Metodology: A total of 150 resin samples were made, which were divided into 3 groups of denture resin (conventional thermally activated, milled and 3D printed) (n= 50) and subdivided into 5 denture cleaners (Distilled water, Corega Tabs, Efferdent, NaOCl 1.0%, Listerine Cool Hint) (n= 10). The roughness properties (Ra) and chromatic difference (ΔE00) were evaluated during 90 days and 180 days of overnight cleaning. Data were evaluated by two-way ANOVA and Tukey's test for multiple comparisons (P<.05).

Results: Listerine had significantly higher Ra and ΔE values (P<.001) compared to other solutions, being significant in conventional resin at 180 days (P<.001).

Conclusions: The use of Listerine as an overnight cleaner presents greater damage to the optical and surface properties of denture base resins, mainly with conventional resin, with 1% NaOCl being a valid option in relation to cost-benefit.

Mandibular deviation (MD) is a common reconstruction sequela after segmental mandibulectomy. Although proper postoperative rehabilitation is critical for MD management and minimization, the information available is limited. This report describes postoperative rehabilitation with an occlusal splint fabricated using computer-aided design (CAD) and computer-aided manufacturing (CAM) (CAD/CAM-OS) and the results of a threedimensional occlusal analysis using an intraoral scanner after hemimandibulectomy and plate reconstruction. Despite the short follow-up, adherence to postoperative rehabilitation with CAD/CAM-OS for MD correction, even during radiotherapy, was demonstrated by the digital workflow and analysis results.