Maintenance requirements of implant-supported fixed prostheses opposed by implant-supported fixed prostheses, natural teeth, or complete dentures: a 5-year retrospective study

PURPOSE: The purpose of this study was to compare the maintenance requirements of implant-supported fixed prostheses with cantilever arms in edentulous jaws when opposed by fixed prostheses of similar design, by natural teeth, or by complete dentures. MATERIALS AND METHODS: The maintenance requirements for the 5-year follow-up period were obtained by examining the dental records of 37 people. Six were provided with fixed prostheses in both arches, 22 with a fixed prosthesis in the mandible opposed by a complete denture, and 9 with a fixed prosthesis opposed by natural teeth. Everyone was treated with Nobel Biocare implants using standard implant and prosthetic protocols. RESULTS: The denture teeth and acrylic resin were repaired on 44 occasions in the group with implants in both jaws, on 14 occasions in the group with implants opposed by natural teeth, and twice in the group in which the implants were opposed by a complete denture. The group with implants in both jaws was more likely to fracture the gold-alloy framework, which occurred on six occasions. The group with implants in both jaws was significantly different from the other two groups in relation to higher incidence of fracture of the teeth and gold-alloy framework. CONCLUSION: The maintenance requirements of implant-supported fixed prostheses with cantilever arms opposed by fixed prostheses of similar design were much greater than when opposed by natural teeth or complete dentures.     

Marginal and internal fit of four-unit zirconia fixed dental prostheses based on digital and conventional impression techniques

Objectives

The aim of this in vitro study was to evaluate the marginal and internal fit of CAD/CAM-generated four-unit zirconia fixed dental prostheses made with digital and conventional impressions.

Materials and method

A titanium master model was used. For group conventional impression (CI), 12 polyether impressions of the master model with Impregum^TM were made. For group digital impression (DI), 12 digital impressions of the master model using Lava^TM C.O.S. system were made. The replica technique was applied. The Mann–Whitney U statistical test was applied to detect statistical differences between the groups, in terms of marginal and internal fit. Face-by-face comparisons between groups were also carried out.

Results

Groups DI and CI presented mean marginal fit of 63.96 and 65.33 μm, respectively, and showed no statistically significant difference. Groups DI and CI presented significantly different internal fit with mean values of 58.46 and 65.94 μm, respectively. Group DI showed statistically significantly lower values for marginal and internal fit on premolar mesial face, and on molar distal and palatal faces.

Conclusions

Frameworks fabricated from digital and conventional impressions showed clinically acceptable marginal fit. Frameworks fabricated from digital impression demonstrated better internal fit than ones fabricated from conventional impression. Reviewing each retainer face, digital impression showed better marginal and internal fit at the premolar mesial and molar distal faces.

Clinical relevance

The results of this in vitro study show that digital impressions made with the Lava^TM C.O.S. system and its digital workflow are suitable for fabricating four-unit zirconia frameworks, with regard to marginal and internal fit requirements.     

Maintenance requirements of implant-supported fixed prostheses opposed by implant-supported fixed prostheses, natural teeth, or complete dentures: A 5-year retrospective study.

Purpose

The purpose of this study was to compare the maintenance requirements of implant-supported fixed prostheses with cantilever arms in edentulous jaws when opposed by fixed prostheses of similar design, by natural teeth, or by complete dentures.

Materials and Methods

The maintenance requirements for the 5-year follow-up period were obtained by examining the dental records of 37 people. Six were provided with fixed prostheses in both arches, 22 with a fixed prosthesis in the mandible opposed by a complete denture, and 9 with a fixed prosthesis opposed by natural teeth. Everyone was treated with Nobel Biocare implants using standard implant and prosthetic protocols.

Results

The denture teeth and acrylic resin were repaired on 44 occasions in the group with implants in both jaws, on 14 occasions in the group with implants opposed by natural teeth, and twice in the group in which the implants were opposed by a complete denture. The group with implants in both jaws was more likely to fracture the gold-alloy framework, which occurred on six occasions. The group with implants in both jaws was significantly different from the other two groups in relation to higher incidence of fracture of the teeth and gold-alloy framework.

Conclusion

The maintenance requirements of implant-supported fixed prostheses with cantilever arms opposed by fixed prostheses of similar design were much greater than when opposed by natural teeth or complete dentures.     

Full arch digital scanning systems performances for implant-supported fixed dental prostheses: a comparative study of 8 intraoral scanners

PurposeCompare the accuracy of intraoral digital impression in full-arch implant-supported fixed dental prosthesis acquired with eight different intraoral scanner (Ios).MethodsA polymethyl methacrylate acrylic model of an edentulous mandible with six scan-abutment was used as a master model and its dimensions measured with a coordinate measuring machine. Eight different Ios were used to generate digital impression: True Definition, Trios, Cerec Omnicam, 3D progress, CS3500, CS3600, Planmeca Emelard and Dental Wings. Fifteen digital impressions were made. A software called “Scan-abut” was developed to analyse and compare the digital impression with the master model, obtaining the scanning accuracy. The three-dimensional (3D) position and distance analysis were performed.ResultsMean value of the 3D position analysis showed that the True Definition (31 μm ± 8 μm) and Trios (32 μm ± 5 μm) have the best performance of the group. The Cerec Omnicam (71 μm ± 55 μm), CS3600 (61 μm ± 14 μm) have an average performance. The CS3500 (107 μm ± 28 μm) and Planmeca Emelard (101 μm ± 38 μm) present a middle-low performance, while the 3D progress (344 μm ± 121 μm) and Dental Wings (148 μm ± 64 μm) show the low performance. The 3D distance analysis showed a good linear relationship between the errors and scan-abutment distance only with the True Definition and CS3600.ConclusionsNot all scanners are suitable for digital impression in full-arch implant-supported fixed dental prosthesis and the weight of the output files is independent from the accuracy of the Ios.     

Comparison between digital and conventional impression techniques in children on preference,time and comfort: A crossover randomized controlled trial

Objective

To compare the conventional alginate impression and the digital impression taken with an intraoral scanner of both dental arches in children, using a randomized crossover design.

Trial Design

This is a monocentric, controlled, superiority, randomized, crossover, open study.

Methods

Twenty-four orthodontic patients between 6 and 11 years of age underwent intraoral scanning (TRIOS 3; 3Shape) and alginate impression of both dental arches with an interval of 1 week between the two procedures. Participants were recruited from September 2021 to March 2022 and the study was completed in April 2022. Impression time for the two procedures was compared. Patients were asked which one of the two impression procedures they preferred. A questionnaire including Visual Analogue Scale (VAS) for comfort, pain, gag reflex and difficulty in breathing, was administered to the patients.

Results

Eighteen out of 24 patients preferred digital impression (75%, 95% confidence interval [CI]: 55% to 88%; P = .014). Scanning time was significantly shorter than alginate impression time (difference −118 seconds; 95% CI: −138 to −99; P < .001). Comfort was significantly higher for digital impression (difference 1.7; 95% CI: 0.5 to 2.8; P = .007). There was no difference in pain (difference −0.2; 95% CI: −1.5 to 1.0; P = .686) while gag reflex and breathing difficulties were smaller for digital impression (gag reflex difference −2.5; 95% CI: −4.0 to −0.9; P = .004 and breathing difficulties difference −1.5; 95% CI: −2.5 to −0.5; P = −.004).

Conclusions

Digital impression is preferred by children aged 6–11 years and it is significantly faster in acquisition time than conventional alginate impression.

Registration

The study was registered on ClinicalTrials.gov with registration number NCT04220957 on January 7th, 2020 ( https://clinicaltrials.gov/ct2/show/NCT04220957 ).     

CS3600■口扫数字化印模技术与传统硅橡胶印模技术在磨牙全瓷冠修复中的比较

目的:比较数字化口内直接印模技术与传统精细硅橡胶印模技术在磨牙全瓷冠修复中的效果。方法:研究选取2019年10月~2020年1月于华中科技大学同济医学院附属同济医院口腔修复科行磨牙全瓷单冠修复治疗的患者32例,共计36颗患牙。实验组18颗患牙采用CS3600^■口内扫描仪制取数字化印模,对照组18颗患牙采用传统硅橡胶印模技术制取印模。记录两组取模时间、戴牙时间及患者舒适度,修复完成2个月参照改良美国公共卫生署(USPHS)标准对修复体进行评价。结果:实验组取模时间更短、取模更舒适;制作的修复体戴牙时间更短、修复体边缘适合性更好(P<0.05)。结论:在磨牙全瓷冠的修复治疗中,CS3600^■口内扫描技术在取模时间、取模舒适度、戴牙时间和修复体边缘适合性等方面都优于传统硅橡胶印模技术。     

Comparison of the accuracy for three dental impression techniques and index: An in vitro study

ObjectivesThis in vitro study compared the dimensional accuracy of stone index (I) and three impression techniques: tapered impression copings (T), squared impression copings (S) and modified squared impression copings (MS) for implant-supported prostheses.MethodsA master cast, with four parallel implant abutment analogs and a passive framework, were fabricated. Vinyl polysiloxane impression material was used for all impressions with two metal stock trays (open and closed tray). Four groups (I, T, S and MS) were tested (n = 5). A metallic framework was seated on each of the casts, one abutment screw was tightened, and the gap between the analog of implant and the framework was measured with a stereomicroscope. The groups’ measurements (80 gap values) were analyzed using software (LeicaQWin – Leica Imaging Systems Ltd.) that received the images of a video camera coupled to a Leica stereomicroscope at 100× magnification. The results were statistically analyzed with Kruskal–Wallis One Way ANOVA on Ranks test followed by Dunn's Method, 0.05.ResultsThe mean values of abutment/framework interface gaps were: Master Cast = 32 μm (SD 2); Group I = 45 μm (SD 3); Group T = 78 μm (SD 25); Group S = 134 μm (SD 30); Group MS = 143 μm (SD 27). No significant difference was detected among Index and Master Cast (P = .05).ConclusionUnder the limitations of this study, it could be suggested that a more accurate working cast is possible using tapered impression copings techniques and stone index.     

Integration of conventional and digital surgical guide fabrication techniques for the partially edentulous patient: Reducing the number of surgical procedures for a complete arch implant-supported prosthesis

Surgical procedures on partially edentulous patients for complete arch implant-supported prostheses involve remaining tooth extraction, alveolar bone reduction, and implant placement. Traditionally, partially edentulous patients undergo multiple surgeries, which extends the healing time and results in an extensively prolonged total treatment timeline. This technical article focuses on the fabrication of a more stable and predictive surgical guide to perform multiple surgical procedures in a single surgical appointment and planning a complete arch implant-supported prosthesis for the partially edentulous patient.     

Comparison of treatment outcomes and time efficiency between a digital complete denture and conventional complete denture: A pilot study

BackgroundThe authors of this study aimed to compare the treatment outcomes and time efficiency between digital and conventional complete denture restorations and propose suggestions for clinical use.MethodsThe authors used digital (functionally suitable digital complete denture [FSD]) and conventional complete denture restorations to make 2 dentures each for 10 edentulous patients. All the operations of both techniques before denture delivery were completed in the first 4 visits, and then 2 dentures were delivered successively for the patients. The clinical and laboratory times were recorded to evaluate the time efficiency; treatment outcomes were evaluated via scoring the denture satisfaction of the dentist and patients in a double-blind manner.ResultsThe satisfaction scores of FSDs (7.6-9.6 [dentist's scores], 8.4-10 [patients' scores]) were higher than those of conventional dentures (7.2-9.7 [dentist's score], 7.4-9.8 [patients' scores]), but there were no significant differences. The clinical and laboratory operation times of the FSD group were less than those of the conventional group, saving an average of 28.0 minutes and 64.3 minutes in the clinic and laboratory, respectively.ConclusionsFSD technology can improve the efficiency of clinical and laboratory operations and shorten the manufacturing cycle of dentures. The occlusion stability of FSDs was statistically better than that of traditional dentures, but there was no statistical difference in other clinical indicators.Practical ImplicationsFSD technology is low cost and easy to operate and has several applications. Compared with conventional complete denture restoration technology, FSDs can save time and have a comparable clinical effect.This clinical trial was registered at the Chinese Clinical Trial Registry. The registration number is ChiCTR1900021722.     

Accuracy of digital complete dentures: A systematic review of in vitro studies

Statement of problemReports on digital complete dentures (CDs) are increasing. However, systematic reviews on their accuracy and influencing factors are lacking.PurposeThe purpose of this systematic review was to evaluate the accuracy of digital CDs and to summarize influencing factors.Material and methodsAn electronic search of the English language literature from January 2009 to October 2019 was performed in the database PubMed/MEDLINE, with the results enriched by manual searches and citation mining. Factors investigated in the selected articles included the fabrication technique, type of computer-aided design and computer-aided manufacturing (CAD-CAM) system, shape of reference model, long-term service, analytical method, and statistical indicators.ResultsA total of 522 articles were identified, of which 14 in vitro articles met the inclusion criteria. Eight articles compared the adaptation of the denture base between digital and conventional methods, 4 studies evaluated the occlusal discrepancies, 4 compared the trueness or adaptation of the denture fabricated with CAD-CAM milling and 3D printing, 1 compared the denture adaptation with 4 different CAD-CAM systems, and 2 evaluated the adaptation of the denture base before and after incubation in artificial saliva.ConclusionsMost of the studies reported clinically acceptable values for the occlusal trueness and adaptation of digital CDs. The digital CDs showed similar or better adaptation than conventionally fabricated CDs, and the greatest misfit of the intaglio surface was reported in the posterior palatal seal area and border seal area. The fabrication technique, CAD-CAM system, and long-term service were statistically significant in relation to denture accuracy. Clarification is needed concerning the accuracy of digital CDs according to the shape of the cast, the parameters related to the CAD-CAM process, the analytical method, and the statistical indicators. No clear conclusions can be drawn about the superiority of CAD-CAM milling and 3D printing regarding denture accuracy.     

摄影测量与传统印模技术制取牙列缺失种植修复印模精度的比较研究

目的:通过体外实验对比摄影测量与传统印模技术制取牙列缺失种植修复印模的精度。方法:选择1例2019年9月就诊于首都医科大学口腔医学院种植中心的74岁男性上颌牙列缺失患者的上颌石膏模型,其上含螺丝固位基台替代体8个。通过开窗夹板式印模复制该石膏模型,将复制模型作为参考模型。由同1名主治医师用两种方法制取参考模型种植体基台...     

Complications, supplementary treatment, and maintenance in edentulous arches with implant-supported fixed prostheses

The first 50 edentulous arches treated with osseointegrated fixed partial dentures at the Postgraduate Dental Education Center, Orebro, Sweden, were studied retrospectively with concern for complications and time used for supplementary treatment and maintenance. The longest observation period was 9 years, the shortest 3 years, and the mean 5.2 years. Twenty-two percent of the patients experienced fractures of artificial teeth and/or the acrylic resin superstructure. The most severe technical complications were fractured or bent abutment screws (three) and fracture of the framework (one). The average time for supplementary treatment and maintenance was as follows: for surgery, 0.16 hours per prosthesis and year; for prosthodontics, 0.64 hours per prosthesis and year; and for dental laboratory procedures, 1.0 hour per prosthesis and year.     

Peri-implant mucosal level in patients treated with implant-supported fixed prostheses: a 1-year follow-up study

PURPOSE: The purpose of this follow-up study was to quantify the change in the peri-implant mucosal level after treatment of edentulous patients with fixed prostheses on osseointegrated endosseous implants. MATERIALS AND METHODS: Twenty patients were included in the study: 10 were treated in the maxilla, and 10 were treated in the mandible. Both groups had fixed prostheses on osseointegrated Br?nemark implants. Peri-implant mucosal level was measured with a calibrated probe after removal of the prostheses at the 1-year follow-up. These measurements were compared to those made on the original master casts. RESULTS: A larger mean retraction (-) was observed in the mandible (-1.6 mm) compared to the maxilla (-0.8 mm), but there was great variation. The individual values varied from -4.5 to +1.0 mm in the mandible and from -6.0 to +6.0 mm in the maxilla. CONCLUSION: Peri-implant soft tissue recession occurs during the first year in edentulous jaws after treatment with implant-supported fixed prostheses and more so in the maxilla than the mandible.     

The dimensional accuracy of polyvinyl siloxane impression materials using two different impression techniques: An in vitro study

Aim of the Study:

To evaluate and compare the linear dimensional changes of the three representative polyvinyl siloxane (PVS) impression materials and to compare the accuracy of single mix with double mix impression technique.

Methodology:

A study mold was prepared according to revised American Dental Association specification number 19 for nonaqueous elastic dental impression materials. Three PVS impression materials selected were Elite-HD, Imprint^™ II Garant, Aquasil Ultra Heavy. Two impression techniques used were single mix and double mix impression technique. A total of 60 specimens were made and after 24 h the specimens were measured using profile projector.

Statistical Analysis:

The data were analyzed using one-way analyses of variance analysis and significant differences were separated using Student''s Newman–Keul''s test.

Results:

When all the three study group impression materials were compared for double mix technique, the statistically significant difference was found only between Imprint^™ II Garantand Elite-HD (P < 0.05). Similarly, using single mix technique, statistically significant difference were found between Elite-HD and Imprint^™ II Garant (P < 0.05) and also between Aquasil Ultra Heavy and Elite-HD (P < 0.05). When the linear dimensional accuracy of all three impression material in double mix impression technique and single mix impression technique were compared with the control group, Imprint^™ II Garant showed the values more nearing to the values of master die, followed by Aquasil Ultra Heavy and Elite-HD respectively.

Conclusion:

Among the impression materials Imprint^™ II Garant showed least dimensional change. Among the impression techniques, double mix impression technique showed the better results.Key Words: Dimensional accuracy, double mix impression technique, impression materials, polyvinyl siloxane, single mix impression technique