Comparative cost-analysis for removable complete dentures fabricated with conventional, partial, and complete digital workflows

STATEMENT OF PROBLEM

Comparative cost-analysis related to different manufacturing workflows for removable complete denture fabrication is seldom performed before the adoption of a new technology.

PURPOSE

The purpose of this study was to compare the clinical and laboratory costs of removable complete dentures fabricated with a conventional (workflow C), a partial digital (workflow M), and a complete digital (workflow D) workflow and to calculate the break-even points for the implementation of digital technologies in complete denture fabrication.

MATERIAL AND METHODS

Clinical and laboratory costs for each of the investigated workflows and the manufacturing options related to denture base and denture teeth fabrication were collected from 10 private Italian dental laboratories and clinics. The selected variables included the clinical and laboratory manufacturing time needed to complete each workflow (opportunity cost); costs for materials, labor, packaging, and shipping; and capital and fixed costs for software and hardware, including maintenance fees. The effect of manufacturing workflows and their options on the outcomes of interest was investigated by using generalized estimated equations models (α=.05). Cost minimization and sensitivity analysis were also performed, and break-even points were calculated for the equipment capital costs related to the implementation of workflows M and D.

RESULTS

From a laboratory standpoint, workflows M and D and related manufacturing options significantly (P<.001) reduced manufacturing time (5.90 to 6.95 hours and 6.30 to 7.35 hours, respectively), and therefore the opportunity cost of each denture compared with workflow C. Workflow M allowed variable costs savings between 81 and 169 USD, while workflow D allowed for an additional saving of 34 USD. The sensitivity analysis showed that the break-even point related to the capital investment for the equipment needed to implement workflows M and D could be reached, depending on the manufacturing options adopted, between 170 and 933 dentures for workflow M and between 73 and 534 dentures for workflow D. From a clinical standpoint, workflows C and M were almost identical. Conversely, workflow D, which included intraoral scanning, required 1 fewer appointment, saving 0.6 hours of chairside time and about 14 USD for materials compared with M.

CONCLUSIONS

Digital workflows (partial and complete digital workflows) were more efficient and cost-effective than the conventional method of fabricating removable complete dentures, with workflow D showing the lowest opportunity and variable costs and break-even point. Savings increased when stock denture teeth were replaced with milled denture teeth and still further with the adoption of 3-dimensionally (3D) printed denture teeth. Milling equipment and materials for denture base fabrication were more expensive than those for 3D-printing. Milling monobloc dentures reduced opportunity and labor costs but increased material cost.

A comparison of alveolar ridge mucosa thickness in completely edentulous patients

PURPOSE

The purpose of this cross-sectional clinical study was to determine and compare alveolar ridge mucosa thickness at crestal, buccal, and lingual locations of the maxillary and mandibular arches in completely edentulous patients using a dedicated, ultrasonic gingival scanner.

MATERIALS AND METHODS

Thirty-eight completely edentulous subjects were included in the study. In each subject, soft tissue thickness was measured at 28 sites of the edentulous ridge by a single calibrated examiner. Intra-observer reliability was calculated with Intraclass Correlation Coefficients by measuring 10 subjects twice, after 1 week. Measurements (mm) were taken at the buccal, lingual, and crestal aspects of the ridge with a dedicated ultrasonic scanner. Repeated measures ANOVA and paired t-tests were used to compare the mean buccal, lingual, and crestal soft tissue thicknesses at each site. The Generalized Estimating Equations model was used to study the effects of age, sex, and race. Confidence level was set to 95%.

RESULTS

Mean tissue thickness ranged from 0.96  to 1.98 mm with a mean of 1.63 ± 0.25 mm. Intraclass Correlation Coefficients were > 0.97. No significant differences between buccal, crestal, and lingual sites were noted for the mandibular arch as well as at 4 sites on the maxillary arch (maxillary right second molar, maxillary right canine, maxillary left first premolar, maxillary left second molar). However, significant differences in soft tissue thickness were noted for all remaining maxillary sites. Race was found to be positively correlated with tissue thickness, with Black individuals showing a significantly greater thickness than White individuals at 4 sites (maxillary right first molar, maxillary left canine, mandibular right second premolar, mandibular right first molar). Age was found to be positively correlated with tissue thickness at 4 sites (maxillary left central incisor, maxillary left first molar, maxillary left second molar, mandibular left second premolar) and negatively correlated at 2 sites (mandibular right canine, mandibular right second molar). Female sex was positively (maxillary left second premolar, maxillary left second molar) and negatively (mandibular right canine) correlated, respectively, with tissue thickness at 3 sites. When data for anterior and posterior sites were respectively pooled, tissue thickness was significantly less at anterior sextant lingual and crestal sites, while no difference was seen for buccal sites.

CONCLUSION

Statistically significant differences for alveolar ridge mucosa thickness were found at several sites in the maxilla and between anterior and posterior sextants for lingual and crestal sites in the maxillary and mandibular arches. Tissue thickness differences were also noted for race with Black individuals showing greater tissue thickness at some sites. Age and sex did not show a clear effect on tissue thickness. Recorded differences in tissue thickness were however small and appear of uncertain clinical significance.

Reverse scan body: The scan pattern affects the fit of complete-arch prototype prostheses

PURPOSE

To assess the effect of different scan patterns on the fit of implant-supported complete-arch prototype prostheses fabricated via a complete digital extraoral protocol with a reverse scan body.

MATERIALS AND METHODS

A mandibular cast with four multi-unit abutment (MUA) implant analogs with adequate antero-posterior spread served as the reference cast, simulating a common clinical patient situation, and a polymethylmethacrylate interim screw-retained prosthesis was fabricated on it. Novel reverse scan bodies were connected to the interim prosthesis on the intaglio of the MUA abutments and extraoral scanning was performed with a white light intraoral scanner (TRIOS 4; 3 shape) and three different scan patterns: starting from the occlusal surface of the interim prosthesis (O-group), starting from the intaglio (I-group), and helix pattern (H-group).  The resulting STL files from the three groups were then imported to computer-aided design (CAD) software and after the digital design, the STL files were exported to a computer-aided manufacturing (CAM) milling machine which generated a total of 15 CAD-CAM milled prototype prostheses per group. Two clinicians assessed the fit of each digitally fabricated prototype prosthesis on the reference cast, utilizing the screw-resistance test and radiographic evaluation. Fisher's exact test was used to test the difference between the three groups, and Cohen's k-score was used to assess the inter-examiner agreement.

RESULTS

Out of the three different groups, the O-group scan pattern led to 100% prosthesis fit, while the prototype prostheses generated from I- and H-groups had 80% and 53% fit, respectively. The results were statistically significant (p = 0.008).

CONCLUSIONS

Occlusal scan pattern leads to fitting milled prototype prostheses after extraoral scanning with reverse scan bodies without intraoral implant data acquisition.

Evaluation of marginal and internal fit of single crowns manufactured with an analog workflow and three CAD-CAM systems: A prospective clinical study

PURPOSE

This prospective clinical study evaluated and compared the marginal and internal fit of crowns fabricated with an analog workflow and three different computer-aided design and computer-aided manufacturing (CAD-CAM) systems.

MATERIALS AND METHODS

Twenty-five participants in need of a single complete-coverage molar or premolar crown were recruited in the study. Twenty-two completed the study, and three participants dropped out. Teeth were prepared according to a standardized protocol by one operator. For each participant, one final impression was made with polyether material (PP) and three intraoral scanners: CEREC Omnicam (C), Planmeca Planscan (PM), and True Definition (TR). For the PP group, crowns were fabricated with a pressable lithium disilicate ceramic, whereas for the other three groups (C, PM, and TR), crowns were designed and milled with dedicated CAD-CAM systems and materials. Marginal (vertical and horizontal) and internal discrepancies between the crowns and tooth preparation were measured at various locations with digital superimposition software. Data was analyzed for normality with Kolmogorov-Smirnov and Shapiro-Wilk tests and then compared with one-way ANOVA and Kruskal-Wallis tests.

RESULTS

Mean vertical marginal gap values were 92.18 ± 141.41 μm (PP), 150.12 ± 138.06 μm (C), 129.07 ± 109.96 μm (PM), and 135.09 ± 112.03 μm (TR). PP group had statistically significantly smaller vertical marginal discrepancy (p = 0.001) than all other groups, whereas no significant difference was detected among the three CAD-CAM systems (C, PM, and TR). Horizontal marginal discrepancies were 104.93 ± 111.96 μm (PP), 89.49 ± 119.66 μm (C), 113.36 ± 128.49 μm (PM), and 136.39 ± 142.52 μm (TR). A significant difference was detected only between C and TR (p < 0.0001). Values for the internal fit were 128.40 ± 49.31μm (PP), 190.70 ± 69.79μm (C), 146.30 ± 57.70 μm (PM), and 168.20 ± 86.67 μm (TR). The PP group had a statistically significant smaller internal discrepancy than C (p < 0.0001) and TR groups (p = 0.001), whereas no significant difference was found compared to the PM group.

CONCLUSION

Posterior crowns fabricated with CAD-CAM systems showed vertical margin discrepancy greater than 120 μm. Only crowns fabricated with the conventional methodology had vertical margins below 100 μm. Horizontal marginal discrepancy was different among all groups, and only CEREC CAD-CAM was below 100 μm. Internal discrepancy was less for crowns fabricated with an analog workflow.

Effect of implant angulation and patrice on the retention of overdenture attachment systems: An in vitro study

PURPOSE

To test the retention of two different overdenture attachment matrices and straight abutments when implants are placed at 0-, 15- and 30- degree diverging angulations as well as the retention of 15-degree-angled abutments to correct the overall angulation to 0-degrees.

MATERIALS AND METHODS

Matching aluminum blocks were machined to incorporate two dental implants at 0-degree, 15-degree, and 30-degree relative angulations and overdenture attachments to simulate a two-implant overdenture. At 0-degree, 15-degree, and 30-degree implant angulation, straight abutments were studied. At 30-degree implant angulation, an additional group was compared utilizing 15-degree angulated abutments that corrected the overall implant angulation to 0-degrees. A custom-designed testing apparatus that allowed automated insertion and removal of the simulated overdenture was designed, with three independent testing stations, each consisting of one simulated arch and one simulated overdenture base. The baseline and residual retention forces after 30,000 dislodging cycles of the simulated overdenture were measured. One-way ANOVA was used to compare retention differences among different color patrices within the 0-, 15-, and 30-degree implant angulation groups followed by Tukey's multiple comparison test. Two sample t-tests were used to compare 0-degree vs. 15-degree implant groups with straight abutments and 30-degree implant groups with straight abutments vs. 30-degree implant groups with angulated abutments.

RESULTS

Regardless of implant angulation or abutment correction, the change in retention exhibited by the Novaloc® system after testing was not statistically significant for all patrice types (p>0.05); however, the change in retention exhibited by the Locator® system was statistically significant for the tested group (p = 0.0272). In both the Novaloc® and Locator® systems, the baseline and final retention values provided by the different patrices were significantly different except for the white and green Novaloc® patrices in the 15-degree divergent implant group which did not meet the specified level of significance (p = 0.0776).

CONCLUSION

Within the limitations of this study, implant angulations up-to 15 degrees do not affect differential change in retention of Novaloc® patrices. There is no difference between Novaloc® white inserts (light retention value) and green inserts (strong retention values) when implants diverge up-to 15-degrees. When Novaloc® straight abutments were placed on implants diverging by 30-degrees, blue extra-strong retention inserts outperformed yellow medium retention inserts by maintaining a higher retention value after 30,000 cycles. When utilizing Novaloc® 15-degree angulated abutments that correct the overall implant angulation to zero degrees, the red light retentive patrice provides steady retention. Finally, the Locator®-green patrice system provides greater retention than the comparable Novaloc®-blue patrice combination; however, it also loses more retention after 30,000 cycles. This article is protected by copyright. All rights reserved.

EPA Consensus Project Paper: Failure Rates of Direct Versus Indirect Single-Tooth Restorations. A Systematic Review and Meta-Analysis

INTRODUCTION

The purpose of this systematic review and meta-analysis was to evaluate and compare the failure rates of direct and indirect restorations for single-tooth restorations.

METHODS

A literature search was conducted by using electronic databases and relevant references for clinical studies on direct and indirect dental restorations with a follow-up of at least 3 years. The risk of bias was assessed with the ROB2 and the ROBINS- I tools. The I2 statistic was used for the assessment of heterogeneity. The authors reported summary estimates of annual failure rates of single-tooth restorations using a random-effects model.

RESULTS

Of 1415 screened articles, 52 (18 RCTs, 30 prospective, 4 retrospective) met the inclusion criteria. No articles with direct comparisons were identified. No significant difference was found in the annual failure rates of single teeth restored with either direct or indirect restorations, which were calculated as 1% using a random-effects model. High heterogeneity was found, ranging from 80% (P⟨0.01) for studies on direct restorations to 91% (P⟨0.01) for studies on indirect restorations. Most of the studies presented some risk of bias.

CONCLUSIONS

Annual failure rates were similar for direct and indirect single-tooth restorations. Further randomized clinical trials are needed to draw more definitive conclusions.

Survival rates, patient satisfaction, and prosthetic complications of implant fixed complete dental prostheses: a 12-month prospective study

PURPOSE

To determine the survival rate, incidence of prosthetic complications, and patient satisfaction of implant fixed complete dental prostheses (IFCDPs) after a mean observation period of 1.4 years.

MATERIALS AND METHODS

Twenty-eight (28) eligible participants were recruited according to specific inclusion and exclusion criteria. The definitive metal-acrylic resin IFCDPs consisted of titanium bars veneered with acrylic resin and acrylic denture teeth. Prosthodontic complications, divided into major and minor, were monitored. Parameters such as gender, jaw location, bruxism, and occlusal scheme were evaluated. Moreover, a questionnaire was administered throughout the study to assess patient satisfaction. Poisson regression as well as repeated measures ANOVA were used for statistical analysis.

RESULTS

Fourteen (14) males and 14 females were enrolled and followed-up at 3, 6, and 12 months. All IFCDPs survived (100% survival rate). The most frequent minor complication was the loss of material used to close the screw access hole (20% out of total complications). The most frequent major complication was chipping of the acrylic denture teeth (77.14% out of total complications). Gender (p = 0.008) and bruxism (p = 0.030) were significant predictors for the total major complications (major wear and major chipping) while occlusal scheme was a significant predictor for major chipping events (p = 0.030).

CONCLUSIONS

While IFCDPs demonstrated high prosthetic survival rates, they also exhibited a high number of chipping events of the acrylic veneering material, especially in males, bruxers, and individuals with canine guidance occlusion. However, the occurrence of these prosthetic complications did not negatively affect patient satisfaction.

Reverse scan body: A complete digital workflow for prosthesis prototype fabrication

PURPOSE

To assess the accuracy of fit of prosthesis prototypes fabricated via a complete digital workflow protocol with a reverse scan body skipping intraoral scanning for implant data acquisition.

MATERIALS AND METHODS

A maxillary stone cast with four multiunit abutment implant analogs (Screw-Retained Abutments, Institut Straumann AG, Basel, Switzerland) with adequate anteroposterior spread simulated a common clinical patient situation. This stone cast served as the master cast and an interim screw-retained prosthesis was fabricated on it. Novel reverse scan bodies were connected to the interim prosthesis, and extraoral scanning was performed with a white light intraoral scanner. The produced standard tessellation language (STL) files were then imported to computer-assisted design software and after the digital design, the STL file was exported to a computer-assisted machining milling machine and a three-dimensional (3D) printer to produce a total of 50 milled and 50 printed fixed complete denture prototypes, respectively. Two clinicians assessed the accuracy of fit of each digitally fabricated prosthesis prototype on the master cast, utilizing the screw-resistance test and radiographic evaluation. Out of the 100 prototypes, 94% (94/100) were fitting accurately. Fisher's exact test was used to test the difference among the groups. The test revealed statistically significant results (p = 0.027).

RESULTS

Out of the 50 digitally fabricated milled prosthesis prototypes, 50 (100%) presented with accurate fit under in vitro assessment. Out of the 50 digitally fabricated 3D printed prototypes, 44 (88%) presented with accurate fit under in vitro assessment.

CONCLUSIONS

Accurately fitting digitally fabricated prosthesis prototypes can be milled after extraoral scanning with reverse scan bodies without intraoral implant data acquisition.

Complete Digital Workflow for Prosthesis Prototype Fabrication with Double Digital Scanning: Accuracy of Fit Assessment

PURPOSE

To assess the accuracy of a complete digital workflow protocol for fabrication of printed prosthesis prototypes for maxillary immediate loading treatment.

MATERIALS AND METHODS

A maxillary stone cast with 4 abutment-level implant analogs with adequate antero-posterior spread was fabricated. This stone cast served as a reference cast and a zirconia prosthesis was also fabricated to serve as an interim prosthesis. Double digital scanning was used for digital scans of the reference cast and the interim prosthesis, respectively. An intraoral scanner (TRIOS^® 3) was used to capture the standard tessellation language (STL) files. These STL files were then imported to computer-aided design (CAD) software (Exocad DentalCAD) and superimposed into a final design STL file that was exported to 3 different (Form 3b+, Carbon M2, Sprintray Pro95) three-dimensional (3D) printers to produce a total of 90 printed prototypes (n = 30 from each 3D printer). Two blinded clinicians assessed the accuracy of fit of each digitally fabricated prosthesis prototype on the reference cast, utilizing the screw-resistance test and radiographs. The Fisher's exact test was used to test the difference between the groups.

RESULTS

Out of the 90 digitally fabricated prototypes, 86 (95.6%) presented with accurate fit. The accuracy of fit ranged from 87% (26/30) for Sprintray Pro95 to 100% (30/30) for the Form 3b+ and M2 Carbon groups.

CONCLUSIONS

Digitally fabricated prosthesis prototypes can be generated with a complete digital workflow leading to clinically acceptable fit, while reducing the number of appointments and treatment time. The 3D printer had an effect on the accuracy of prosthesis prototype fit.

Complete digital workflow for prosthesis prototype fabrication with double digital scanning: A retrospective study with 45 edentulous jaws

PURPOSE

To assess the accuracy of fit of complete-arch printed prosthesis prototypes generated with a digital workflow protocol for completely edentulous jaws.

MATERIALS AND METHODS

Forty-five edentulous jaws (35 patients) underwent intraoral complete-arch digital scans with the double digital scanning (DDS) technique and the generated standard tessellation language (STL) files were superimposed and imported into computer-aided design software. After STL merging, each master STL file was used for printing a prosthesis prototype. The primary outcome was the accuracy of fit assessment of the printed prototypes on verified master stone casts. Two experienced clinicians tested the accuracy of fit with radiographs and screw-resistance tests. Secondary outcomes were the effect of the scan body shape and implant number on the accuracy of fit.

RESULTS

Out of the 45 DDS-generated prosthesis prototypes, 39 presented with accurate fit on verified master stone casts, yielding an 86.70% accuracy of fit. Cylindrical scan bodies led to 100% accuracy of fit (25/25), whereas polygonal scan bodies presented with 70% accuracy of fit (14/20). Four implant-supported prostheses yielded 100% accuracy of fit (12/12), compared with 25/29 (86.30%) accuracy of fit for the six-implant-supported ones. Fisher's exact test was used to assess the effect of different scan body shapes (p = 0.005) and implant number on accuracy of fit. Chi-squared test was used to assess the association between the number of implants per arch and the accuracy of fit (p = 0.039).

CONCLUSIONS

Thirty-nine out of 45 complete-arch prosthesis prototypes generated with a completely digital workflow presented with clinically acceptable fit. The effect of the scan body design and implant number was statistically significant, favoring cylindrical scan bodies and four-implant-supported prostheses.

Complete Digital Workflow for Prosthesis Prototype Fabrication with the Double Digital Scanning (DDS) Technique: A Prospective Study on 16 Edentulous Maxillae

PURPOSE

To assess the accuracy of fit of milled prosthesis prototypes for completely edentulous patients using a digital workflow.

MATERIALS AND METHODS

Sixteen patients received intraoral full-arch digital scans with the double digital scanning (DDS) technique and the generated standard tessellation language (STL) files were superimposed and imported into computer-aided design software (Exocad DentalCAD, exocad GmbH, Darmstadt, Germany) for design. After the design, each master STL file was used for computer-aided manufacturing of the prosthesis prototypes through a complete digital workflow. The primary outcome was the accuracy of fit assessment of the digitally fabricated prototypes on verified patient master stone casts. Two blinded clinicians tested the accuracy of fit of the milled prosthesis prototypes on the verified master stone casts utilizing the screw-resistance test and direct observation.

RESULTS

Out of the 16 digitally fabricated prototypes from intraoral full-arch digital scans, all 16 presented with an accurate fit on verified master stone casts.

CONCLUSIONS

Digitally fabricated full-arch prosthesis prototypes can be generated with a complete digital workflow leading to clinically acceptable fit.

Insertion and removal torque of dental implants placed using different drilling protocols: An experimental study on artificial bone substitutes

PURPOSE

The aim of this in vitro study was to measure the insertion and removal torque values of dental implant replicas inserted into artificial bone blocks using different surgical burs and drilling protocols.

MATERIALS AND METHODS

Four types of artificial, polyurethane bone blocks were used with different thicknesses (1 and 2 mm) and densities (soft-1 mm, soft-2 mm, dense-1 mm, and dense-2 mm) of the simulated cortical and cancellous bone, respectively. Each bone construct was drilled with Straumann and Densah drills in both clockwise and counterclockwise directions for a total of 16 experimental conditions. For every scenario, 38 implant replicas were inserted and then removed after 1 min. Outcomes of interest were the insertion and removal torque values which were recorded by a torque meter. ANOVA and Tukey HSD tests were used to assess differences across each combination of drill, direction, and bone type.

RESULTS

Densah counterclockwise registered statistically greater values for both insertion and removal torque, followed by Densah clockwise, Straumann counterclockwise, and Straumann clockwise. Increasing insertion and removal torque values were progressively reported for bone type (soft-1 mm, dense-1 mm, soft-2 mm, and dense-2 mm). The mean values of insertion and removal torque were significantly different (p < 0.05) across the four bone types, different burs, and with the two drilling modalities.

CONCLUSIONS

Densah bur resulted in significantly greater values of torque compared to the Straumann drills for all the experimental conditions. The thickness of the cortical layer and the counterclockwise drilling direction play a significant role in determining the implant insertion torque.

Titanium Nitride Coated Implant Abutments: From Technical Aspects And Soft tissue Biocompatibility to Clinical Applications. A Literature Review

PURPOSE

To review the most up to date scientific evidence concerning the technical implications, soft tissue biocompatibility, and clinical applications derived from the use of titanium nitride hard thin film coatings on titanium alloy implant abutments.

MATERIALS AND METHODS

A review was performed to answer the following focused question: "What is the clinical reliability of nitride coated titanium alloy abutments?". A MEDLINE search between 1980 and 2021 was performed for investigations pertaining to the clinical use of nitride coated titanium alloy implant abutments (TiN) in case reports, case series, and short- and long-term non/randomized controlled clinical trials. Literature analysis led to addition evaluation of research related to the technical and biological aspects, as well as the physicochemical characteristics of TiN hard thin film coatings and their impact on titanium abutment biocompatibility, mechanical properties, macroscopic surface topography, and optical properties. Therefore, preclinical data from biomechanical and in vitro investigations were also considered as inclusion criteria.

RESULTS

The limited number of clinical investigations published made a systematic review and meta-analysis not possible, therefore a narrative review was conducted. TiN coatings have been applied to dental materials and instruments to improve their clinical longevity. Implant abutments are coated with titanium nitride to mask the titanium oxide surface and enhance its surface characteristics providing the TiN abutment surface with a low friction coefficient and a very high chemical inertness. TiN coating is suggested to reduce early bacterial colonization and biofilm formation and enhance fibroblast cell proliferation, attachment and adhesion when compared to Ti controls. Additionally, studies indicate that hard thin film coatings enhance the mechanical properties (hardness and wear resistance) of titanium alloy and appears as a yellow color when deposited on the titanium alloy substrate. To date, clinical investigations show that nitride coated titanium abutments provide promising short-term clinical outcomes.

CONCLUSIONS

Published research on nitride-coated abutments is still limited, however, the available biomedical research, mechanical engineering tests, in vitro investigations, and short-term clinical trials have, to date, reported promising mechanical, biological, and esthetic outcomes.

Screw-Retained Surgical Guide for Implant Placement in Terminal Dentition Patients With Existing Implants

For patients with existing implants in need of additional implant placement, the use of the existing implants for guide fixation seems to be a logical alternative. Current options for the fabrication of surgical guides involve creating surgical guides that are mucosa-borne and/or retained by fixation pins. Since these existing techniques involve inherent inaccuracies, the fabrication of surgical guides that are screw-retained at the implant- or abutment-level would eliminate the introduction of those same fundamental inaccuracies. The purpose of the present technical report is to illustrate a step-by-step digitally planned guided implant placement protocol for terminal dentition patients with salvageable existing implants requiring full-arch implant rehabilitation. The advantages of this protocol include enhancing the accuracy of guided implant placement with screw-retention vs the traditional mucosa- or fixation pin support. Thus, this simplifies the transition from failing teeth to implants by ensuring that fixed provisionalization serves both functional and esthetic requirements. This protocol can also predictably reduce chairside time and adjustments at the surgical implant placement appointment. This article is protected by copyright. All rights reserved.

Digital VS Conventional Full-Arch Implant Impressions: A Retrospective Analysis of 36 Edentulous Jaws

PURPOSE

There is a paucity of comparative clinical studies assessing the accuracy of full-arch digital versus conventional implant impressions. The aim of this retrospective study was to compare the three-dimensional (3D) deviations between full-arch digital and conventional implant impressions for edentulous maxillae and mandibles.

MATERIALS AND METHODS

Twenty-seven patients (36 edentulous jaws) were treated with one-piece, screw-retained implant-supported fixed complete dental prostheses (IFCDPs). Twenty-one jaws were maxillary, and 15 were mandibular. Full-arch conventional impressions and intraoral digital scans with scan bodies and an intraoral scanner had been taken during the impression phase. Following verification of the conventional stone casts, the casts were digitized. The generated standard tessellation language (STL) files from both impression techniques were merged and analyzed with reverse engineering software. The primary aim was to evaluate the accuracy between conventional and digital full-arch scans, while the effect of the edentulous jaw in 3D accuracy was the secondary aim.

RESULTS

The cumulative 3D (mean ±SD) deviations between virtual casts from intraoral full-arch digital scans and digitized stone casts generated from conventional implant impressions were found to be 88 ±24 μm. In the maxillary group, the mean ±SD 3D deviation was 85 ±25 μm, compared to 92 ±23 μm for the mandibular group (P = .444).

CONCLUSION

The 3D implant deviations found between the full-arch digital and conventional impressions lie within the clinically acceptable threshold. No statistically significant difference was identified between maxillary and mandibular jaws in terms of 3D deviations. This article is protected by copyright. All rights reserved.

Digital Workflow in Implant Treatment Planning For Terminal Dentition Patients

Treatment planning for the transition of patients from terminal dentition to full-arch implant rehabilitation poses challenges. Such challenges pertain to achieving the new orientation of the occlusal and esthetic plane as well as the change of vertical dimension of occlusion (VDO), while the fixed provisionalization using a digital workflow, still tends to be considered complex and hard to perform. This article illustrates step-by-step the utilization of a digital workflow protocol in the treatment planning for rehabilitation of terminal dentition patients, simplifying the smile design and ensuring that fixed provisionalization serves both the functional and esthetic requirements. This protocol includes facially-driven, three-dimensional (3D) digital smile design and chairside mock-up restoration workflows that enable prosthetically-driven assessment prior to implant treatment planning and 3D printing of surgical templates, which can predictably reduce chairside time and adjustments at the surgical and fixed provisionalization appointment. This article is protected by copyright. All rights reserved.

Clinical Evaluation of Pink Esthetic Score of Immediately Impressed Posterior Dental Implants

PURPOSE

While comparative outcome results for peri-implant crestal bone levels, mucosal margin position, and peri-implant indices have been reported, no studies are available that evaluate and compare the esthetic result of impressions performed immediately with that of impressions performed of healed implants. The purpose of this cross-sectional study was to evaluate the Pink Esthetic Score (PES) of posterior implants restored with an immediate impression workflow compared to implants restored with a delayed impression workflow.

MATERIAL AND METHODS

Twenty-eight eligible participants who had received a single implant crown either in the premolar or molar regions at least 4 months before the study, were identified by an electronic health record review and scheduled for a single-visit study appointment. Esthetic outcomes were measured using the Pink Esthetic Score (PES). Several local- and prosthesis-related factors were recorded and their association with the selected outcome was assessed. Two-sample t-test was used for comparisons between the groups.

RESULTS

PES ranged between 4 and 12 (mean: 8). No significant difference between immediate (8.36 ± 1.12) and delayed (7.76 ± 2.14) impression workflow groups were seen for the total PES (p = 0.25). In addition, individual comparisons between immediately and delayed impressed implants for mesial papilla (1.27 ± 0.47; 0.88 ± 0.78), distal papilla (0.73 ± 0.65; 0.76 ± 0.83), tissue margin (1.73 ± 0.47; 1.47 ± 0.51), tissue contour (1.27 ± 0.65; 0.82 ± 0.64), alveolar process (0.82 ± 0.60; 1.00 ± 0.87), color (1.27 ± 0.65; 1.29 ± 0.69), and texture (1.36 ± 0.50; 1.53 ± 0.62) did not show significant differences.

CONCLUSIONS

The current study suggests that the Pink Esthetic Score is not significantly different between single posterior implants impressed with the immediate and delayed implant workflows. This article is protected by copyright. All rights reserved.

Esthetic and Functional Rehabilitation of an Adolescent Patient with Severe Dental Fluorosis: A Clinical Report

Dental fluorosis is a developmental defect affecting amelogenesis. It presents clinically in different forms depending on the concentration, duration, and time of exposure to fluoride. Several therapeutic modalities have been described to manage mild and moderate forms of dental fluorosis; however, limited literature is available on the restorative management of severe forms of dental fluorosis, specifically in young individuals. This clinical report describes a complete prosthodontic rehabilitation of an adolescent patient with severe dental fluorosis affecting his permanent dentition. The patient was treated with a combination of monolithic, minimally-veneered zirconia crowns and direct composite resins. At the 1-year follow-up appointment, there were no complications, and both the patient's oral health and the integrity of the restorations remained stable.

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.

Removable Partial Dentures with Polyetheretherketone Framework: The Influence on Residual Ridge Stability

PURPOSE

To provide, in a clinical case-control study, 1-year data on edentulous residual ridge dimensional changes for patients wearing removable partial dentures (RPD) with Polyetheretherketone (PEEK) framework, fabricated with a digital workflow, and a control group of untreated patients.

MATERIALS AND METHODS

Ten patients were treated with PEEK RPD, and six controls were studied. Intraoral scans at baseline (T0) and after a median period of 1 year (T1) were superimposed, trimmed, and reoriented (T0r and T1r), moved to a metrology software, and realigned. A curve (C0) was then traced on T0r, along the residual ridge crest; its projection (C1) on T1r was obtained. The mean distance C0-C1 was the dependent variable of interest and represented the 1-year changes in the height of the edentulous ridge. In addition, mean 3D distance between T0 and T1 at each edentulous area was measured. Differences in these outcomes measured between RPD treated and control groups were statistically assessed.

RESULTS

Twenty-six and 14 edentulous areas were investigated in the RPD treated and control groups, respectively. No significant differences were observed for potentially confounding variables, such as median follow-up time (12.5 vs. 13 months, respectively), the alignment accuracy between T0r and T1r (0.01 mm vs. 0 mm, respectively), the median number of remaining teeth (6 vs. 8.5, respectively), and the median length of edentulous areas (25.5 mm vs. 22.8 mm, respectively). For the outcomes of interest, no statistically significant difference was seen in the mean distance between C0 and C1 (i.e., changes in residual ridge height: -0.39 ± 0.52 mm vs. -0.52 ± 0.54 mm, respectively) or in the mean 3D distance at corresponding points of the denture bearing areas (-0.3 ± 0.46 mm vs. -0.4 ± 0.35, respectively).

CONCLUSIONS

Although 1 year is a relatively short observation period, this clinical study shows that there are no short-term differences in edentulous residual ridge height and overall dimensions between patients wearing PEEK RPD, fabricated with a digital workflow, and controls without an RPD.

Complete Digital Workflow for Mandibular Full-Arch Implant Rehabilitation in 3 Appointments

The aim of this clinical report is to describe a complete digital workflow protocol for mandibular full-arch implant rehabilitation from guided surgery to definitive prosthesis in only 3 appointments. This expedited protocol allows for guided implant placement with a system of stackable surgical templates and CAD/CAM prosthodontic rehabilitation using a digital workflow. At the first appointment, a guided implant placement protocol with the stackable template concept was done followed by immediate loading with a prefabricated interim prosthesis. At the same appointment, the Double Digital Scanning (DDS) technique was used for scanning, maxillomandibular relationship registration and virtual articulation. The anchor pins from guided surgery were used as fiducial markers for DDS data superimposition. At the second appointment, the prosthesis prototype was tried-in and adjustments were made. At the third appointment, the definitive monolithic zirconia full-arch prosthesis was delivered.

Clinical Evaluation of Crestal Bone Levels, Peri-Implant Indices, and Mucosal Margin Position of Immediately Impressed Posterior Dental Implants: A Cross-Sectional Study

PURPOSE

This is a cross-sectional clinical study to evaluate crestal bone levels, mucosal margin position, probing depths, bleeding on probing, and plaque and bleeding indices of implants restored with an immediate impression workflow compared to implants restored with a delayed impression workflow.

MATERIALS AND METHODS

Patients who had received a posterior single implant crown in the premolar and molar regions were identified and scheduled for a single-visit study appointment. Outcome measurements included soft tissues peri-implant indices, peri-implant mucosal margin position, and crestal bone levels. Several systemic-, local-, and prosthesis-related factors were recorded. Bitewing radiographs were used to assess crestal bone levels. Wilcoxon rank sum test was used to compare the medians of continuous measurements and Pearson chi-square test (or Fisher's exact test) was used to compare the distributions of categorical variables between the two groups.

RESULTS

Twenty eight patients were included. Crestal bone levels, peri-implant mucosal margin position and peri-implant soft tissue parameters for the immediately impressed group were not statistically different from the delayed impressed group, except for probing depth for the immediately impressed buccal site, which was less than that of the delayed group. Mesial bone level for cement-retained crowns was significantly more coronal than for screw-retained ones.

CONCLUSIONS

While an isolated statistical difference was found in probing depth, the current study suggests that there is no clinically significant difference between implants impressed with immediate and delayed implant workflows when considering crestal bone levels, peri-implant mucosal margin position, and most peri-implant indices.

A Comparison Between Fixed and Removable Mandibular Implant-Supported Full-Arch Prostheses: An Overview of Systematic Reviews

PURPOSE

To evaluate the current literature and provide clinical recommendations related to the number of implants, implant characteristics, loading protocols, survival rates, biologic and mechanical complications, patient satisfaction, and financial considerations for mandibular implant-supported full-arch prostheses.

MATERIALS AND METHODS

A PubMed/MEDLINE search for literature published between January 1, 1980 and February 8, 2019, was performed for systematic reviews on this topic. The PICO question was: In mandibular fully edentulous patients treated with implant full-arch prostheses, is there any difference between fixed and removable implant prostheses in terms of implant and prosthesis survival rates? Only systematic reviews with or without meta-analyses were included. The findings varied based on the type of implant full-arch prosthesis.

RESULTS

High survival rates for implants and prostheses have been reported for fixed and removable implant full-arch prostheses in the mandible. Immediate loading procedures present with high survival rates for both fixed and removable prostheses. There are differences in the number of implants, implant characteristics, complications, and financial implications between these two types of prostheses, which clinicians need to account for as part of the treatment planning process.

CONCLUSION

Implant-supported overdentures and implant-supported fixed complete dentures represent clinically successful treatment approaches. In cases where both treatment options are indicated, patient expectations and cost should be the determining factors for selecting a treatment modality.

Recommendations for Implant-Supported Full-Arch Rehabilitations in Edentulous Patients: The Oral Reconstruction Foundation Consensus Report

The tasks of Working Groups 1 to 6 at the 4th Consensus Meeting of the Oral Reconstruction Foundation were to elucidate clinical recommendations for implant-supported full-arch rehabilitations in edentulous patients. Six systematic/narrative reviews were prepared to address the following subtopics: (1) the influence of medical and geriatric factors on implant survival; (2) the prevalence of peri-implant diseases; (3) the influence of material selection, attachment type, interarch space, and opposing dentition; (4) different interventions for rehabilitation of the edentulous maxilla; (5) different interventions for rehabilitation of the edentulous mandible; and (6) treatment choice and decision-making in elderly patients. Consensus statements, clinical recommendations, and implications for future research were determined based on structured group discussions and plenary session approval.

Accuracy of 3D Printed Implant Casts Versus Stone Casts: A Comparative Study in the Anterior Maxilla

PURPOSE

To conduct an in vitro comparison of the amount of three-dimensional (3D) deviation of 3D printed casts generated from digital implant impressions with an intraoral scanner (IOS) to stone casts made of conventional impressions.

MATERIAL AND METHODS

A maxillary master cast with partially edentulous anterior area was fabricated with two internal connection implants (Regular CrossFit, Straumann). Stone casts (n = 10) that served as a control were fabricated with the splinted open-tray impression technique. Twenty digital impressions were made using a white light IOS (TRIOS, 3shape) and the Standard Tesselation Language (STL) files obtained were saved. Based on the STL files, a digital light processing (DLP) and a stereolithographic (SLA) 3D printer (Varseo S and Form 2) were used to print casts (n = 10 from each 3D printer). The master cast and all casts generated from each group were digitized using the same IOS. The STL files obtained were superimposed on the master cast STL file (reference) to evaluate the amount of 3D deviation with inspection software using the root mean square value (RMS). The independent-samples Kruskal-Wallis test and Dunn's test with Bonferroni correction (for post hoc comparisons) were used for statistical analyses.

RESULTS

The Varseo S group had the lowest median RMS value [77.5 µm (IQR = 91.4-135.4)], followed closely by the Conventional group [77.7 µm (IQR = 61.5-93.4)]. The Form 2 had the highest mean value [98.8 µm (IQR = 57.6-87.9)]. The independent-samples Kruskal-Wallis test revealed a significant difference between the groups (p = 0.018). Post hoc testing revealed a significant difference between Varseo S and Form 2 (p = 0.009).

CONCLUSION

The casts generated from the Varseo S 3D printer had better 3D accuracy than did those from the Form 2 3D printer. Both the Varseo S group and the conventional stone casts groups had similar 3D accuracy.

The Relationships Between Tooth-Supported Fixed Dental Prostheses and Restorations and the Periodontium

PURPOSE

To search the literature and to critically evaluate the findings on the periodontal outcomes of restorations and tooth-supported fixed prostheses.

MATERIALS AND METHODS

PubMed was searched according to a systematic methodology, previously reported, but updated to include a larger database. Filters applied were: Case reports, clinical trial, review, guideline, randomized controlled trial, meta-analysis, systematic reviews, and English. A narrative review was then synthesized to discuss periodontal outcomes related to restorations and tooth-supported fixed prostheses. Relevant data was organized into four sections: Direct restorations, indirect restorations, biologic width or supracrestal tissue attachment and tooth preparation/finish line design.

RESULTS

While increased gingival index, bleeding on probing, probing depth and clinical attachment loss have been associated with subgingival restorations, intracrevicular margins do not cause periodontal diseases. Inflammation and bone loss occur, for both direct and indirect restorations, only with large overhangs. Different restorative materials are associated with different clinical responses when placed in the gingival sulcus or within the epithelial and connective tissue attachments. When the connective tissue attachment is removed, histological changes occur causing its apical shift and subsequent re-establishment. Gingival displacement during impression procedures can cause gingival recession. Emergence profile can have a range of values, not associated with periodontal diseases. Periodontal response appears to be clinically not different when compared among different finish line designs.

CONCLUSIONS

Contemporary procedures and materials used for the placement and fabrication of tooth-supported restorations and fixed prostheses are compatible with periodontal health when adequate patient education and motivation in self-performed oral hygiene are present. Periodontal diagnostic criteria should be thoroughly reviewed before fixed restorative treatments are planned and executed.

A combined analog and digital workflow for retrofitting a monolithic ceramic crown to an existing removable partial denture

A clinical and laboratory workflow for fabricating and retrofitting a monolithic ceramic crown to an existing removable partial denture (RPD) is described. A conventional polyvinyl siloxane impression was made of the prepared tooth with the RPD in place. A stone cast was poured and, after die sectioning, scanned with a tabletop scanner. The ceramic crown was designed and fabricated by using a digital workflow to fit the RPD clasp assembly, providing an adequate undercut for the clasp. The crown was then delivered and the RPD evaluated for adequate fit.

Peri-Implant Diseases and Biologic Complications at Implant-Supported Fixed Dental Prostheses in Partially Edentulous Patients

PURPOSE

This is a single center, retrospective study to assess the prevalence of peri-implant disease and biologic complications in a cohort of partially edentulous subjects in relation to selected prosthetic factors.

MATERIALS AND METHODS

Subjects previously treated with one or more implant-supported fixed dental prosthesis (ISFDPs) were recalled for a comprehensive examination. Clinical and radiographic records were taken and questionnaires were administered. The prevalence of implant failure, peri-implant disease and other biologic complications were correlated with selected prosthetic, clinical and patient-related factors using chi-square and multiple regression analyses.

RESULTS

A convenience sample of 71 subjects with 100 prostheses supported by 222 dental implants were enrolled in the study. The mean follow-up time after prosthesis delivery was 3.3 ± 1.5 years (range of 1-9 years). The cumulative implant survival rate was 99.1%. Peri-implantitis was the most frequent major biologic complication (5% of implants), while the most frequent minor biologic complication was peri-implant mucositis (84.10% of implants). A diagnosis of peri-implant mucositis was more likely associated with cement-retained prostheses compared to screw-retained prostheses (OR 6.8, 95% CI 1.1-78.6, p = 0.045) and for short-span prostheses (≤3 prosthetic units) (OR 2.3, 95% CI 1.1-5.0, p = 0.034). Subject-reported quality of life measures were high regardless of the existence of major and/or minor complications, but decreased with increasing number of minor and total biologic complications.

CONCLUSIONS

Peri-implant mucositis and other minor biologic complications were highly prevalent. The distribution of the observed complications differed based on the method of prosthesis retention and the number of prosthetic units replaced.

Prosthesis Survival Rates and Prosthetic Complications of Implant-Supported Fixed Dental Prostheses in Partially Edentulous Patients

PURPOSE

To determine the prevalence and distribution of prosthetic complications affecting implant-supported fixed dental prostheses (ISFDPs).

MATERIALS AND METHODS

Subjects previously treated with one or more ISFDP(s) were identified from an electronic health record search and recalled for comprehensive clinical examination. Past prosthesis failures and complications were identified from the patient records while any existing complications, not previously recorded, were assessed during examination. ISFDP survival and failure rates were calculated with Kaplan-Meier curves and life table analysis, while regression Poisson analysis was used to identify associations between outcomes and possible patient- and prosthesis-based risk factors.

RESULTS

Seventy-four subjects with 107 ISFDPs were enrolled in the study with a mean time between prosthesis delivery and exam of 3.14 years (range: 1.00-9.00 years). Four prostheses failed, resulting in a cumulative prosthesis survival rate of 96.26%. Prosthetic complications affected 48.59% of ISFDPs, the majority (94.87%) of them minor complications. Only the use of a nightguard was associated with a lower prevalence of prosthetic screw loosening (HR 0.11, 95% CI 0.02-0.59, p = 0.007) while no outcome differences were noted for other variables. Patient satisfaction was high regardless of presence or number of complications.

CONCLUSIONS

ISFDPs demonstrated a high survival rate and overall high, patient-reported satisfaction. Minor prosthetic complications were common but were only significantly associated with nightguard use.

An alternative approach for vestibular extension using temporary coverage of epithelialized palatal grafts

An alternative approach was used to increase the buccal vestibular depth of two edentulous patients, using free epithelialized palatal grafts. Two edentulous patients presented with shallow vestibules and inadequate keratinized tissue width in the mandibular anterior region. These sites were treated with vestibuloplasty followed by placement of an epithelialized palatal graft. In order to minimize graft movement and possible mechanical trauma to the area, the graft was covered with the buccal flap during the initial stages of healing. The patients maintained an increase in the vestibular depth as well as the keratinized tissue width at 14 months and 5 years postoperatively. Successful outcomes in terms of increase in vestibular depth can be achieved with the use of epithelialized palatal graft that is covered during the initial stage of healing. The dental practitioner fabricating the complete denture should be aware of the advantages offered by this alternative surgical technique.

Survival rates and prosthetic complications of implant fixed complete dental prostheses: An up to 5-year retrospective study

STATEMENT OF PROBLEM

Implant fixed complete dental prostheses (IFCDPs) are widely used in the rehabilitation of completely edentulous patients, yet limited information is available on the relationship between prosthetic complications and patient-associated and prosthesis-associated risk factors.

PURPOSE

The purpose of this retrospective study was to assess the prosthetic complication and survival rates of IFCDPs after a mean observational period of 3.5 years.

MATERIAL AND METHODS

Eligible participants were identified by an electronic health record review. The study consisted of a review of the dental record and a single-visit study appointment when a comprehensive examination was performed, including a review of the medical and dental history, clinical and radiographic examination, intraoral photographs, patient satisfaction questionnaire, and occlusal analysis. Prosthodontic parameters and risk factors were assessed, including time with the prosthesis in place, bruxism, occlusal device use, prosthesis material, number of implants, cantilever length, and mode of prosthesis retention. Association between these prosthodontic parameters and risk factors and the observed prosthetic complications was assessed.

RESULTS

A total of 37 participants (mean age 62.35 ±10.39 years) with 48 IFCDPs were included. Thirty-eight prostheses were metal-acrylic resin (MR group), whereas 10 were metal-ceramic (MC group). Five of the 48 prostheses failed during the follow-up period, a cumulative prosthesis survival rate of 88%. Minor complications were more frequent than major complications. The most frequent minor complication was loss of screw access hole material (5.18%/year), whereas the most frequently observed major complication was major wear of the prosthetic material (5.85%/year). A significant association was found between not wearing an occlusal device and minor chipping, loss of access hole material, and framework fracture. Minor chipping was significantly associated with bruxism, whereas the opposing dentition significantly affected the total number of prosthetic complications.

CONCLUSIONS

High survival rates were observed with both MR and MC IFCDPs. No significant difference was found between MR and MC groups in terms of patient satisfaction, as well as total number of prosthetic complications.

Dimensional stability of double-processed complete denture bases fabricated with compression molding, injection molding, and CAD-CAM subtraction milling

STATEMENT OF PROBLEM

Studies evaluating the dimensional stability of denture bases fabricated by the double processing method are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the dimensional stability of denture bases fabricated by 3 different techniques: compression molding, injection molding, and computer-aided design and computer-aided manufacturing (CAD-CAM) subtraction milling.

MATERIAL AND METHODS

Forty-five mandibular denture bases were fabricated from a master cast by a standardized process. A double processing protocol was used with 3 methods: compression molding (PRESS), injection molding (INJECT), or CAD-CAM (CAD). The bases were compared with the titanium master cast after the first processing. By a digital subtraction process, the dimensional stability of the bases was measured at 22 different locations on the intaglio surface. Denture teeth were then positioned according to a standardized protocol, and the denture was processed a second time and finished. The dimensional discrepancy was reassessed after the second processing and compared with the titanium master cast.

RESULTS

In all groups, most of the dimensional changes occurred during the first processing (P<.05), with no statistically significant deformation occurring during the second processing (P>.05). The CAD group presented significantly smaller dimensional changes than PRESS (P<.05) and INJECT (P<.05) groups. No significant difference was found in the dimensional stability in the PRESS and INJECT groups (P>.05).

CONCLUSIONS

Denture bases fabricated by a CAD-CAM methodology exhibit fewer dimensional changes than either compression or injection molding. Distortion occurred during the fabrication of the denture base, and a second processing did not significantly affect the dimensional stability of the denture base.

Technical Complications and Prosthesis Survival Rates with Implant-Supported Fixed Complete Dental Prostheses: A Retrospective Study with 1- to 12-Year Follow-Up

PURPOSE

To report the rate of technical complications and prosthesis survival in a cohort of edentulous patients treated with implant-supported fixed complete dental prostheses (IFCDPs) after a mean observation period of at least 1 year.

MATERIALS AND METHODS

The single-visit examination included clinical and radiographic assessment, occlusal analysis, photographs and questionnaire assessing patient satisfaction in a cohort of 52 patients rehabilitated with 71 IFCDPs (supported by 457 implants). The IFCDPs were assessed for technical complications, number of implants and cantilever extension, retention type and prosthetic material type. Comparison was made between ceramic IFCDPs (Group 1) and metal-resin IFCDPs (Group 2). Kaplan-Meier survival curve analysis was carried out for assessment of prosthesis survival and was done for both Groups 1 and 2 separately. The Cox proportional hazard model was used for survival analysis, adjusting for a number of potential confounders, to evaluate the association between prosthesis survival and several risk factors such as type of opposing occlusion, nightguard use, and presence of bruxism. Responses to patient satisfaction questions were compared with Fisher's exact test.

RESULTS

Out of 71 edentulous arches (52 patients) restored with IFCDPs, 6 IFCDPs had failed, yielding a cumulative prosthesis survival rate of 91.6 % after a mean observation period of 5.2 years (range: 1-12 years) after definitive prosthesis insertion. Three IFCDPs were lost due to implant failures after 5.8 to 11 years of functional loading. Additionally, 3 metal-resin IFCDPs failed due to technical complications. Minor complications were the most frequent complications observed, namely wear of the prosthetic material (9.8% annual rate) being the most common, followed by decementation of cement-retained IFCDPs (2.9%), and loss of the screw access filing material of the screw-retained IFCDPs (2.7%). The most frequently observed major complication was fracture of the prosthetic material (1.9% annual rate), followed by fracture of occlusal screw (0.3%), and fracture of framework (0.3%). The annual rate of wear of prosthetic material was 7.3% for porcelain IFCDPs (n = 19/55) and 19.4% for metal-resin IFCDPs (n = 13/16), yielding a statistically significant difference between the 2 groups (p = 0.01).

CONCLUSIONS

After a mean exposure time of 5.2 years, 91.6% prosthesis survival rates were achieved (65 out of 71 IFCDPs). The most frequent minor technical complication was wear of the prosthetic material with estimated 5-year rate of 49.0%, while the most frequent major complication was fracture of the prosthetic material with estimated 5-year dental unit-based rate of 9.5%. The cumulative rates for "prosthesis free of minor complications" at 5- and 10-years were 60.5% (95% CI: 47.2-71.3%) and 8.9% (95% CI: 2.9-18.0%), respectively. The cumulative rates for "prosthesis free of major technical complications" at 5- and 10-years were 85.5% (95% CI: 73.0-92.5%) and 30.1% (95% CI: 12.0-50.6%), respectively. Presence of bruxism, and absence of a nightguard were associated with increased risk for chipping of the prosthetic material of the IFCDPs.

Complications and survival rates of 55 metal-ceramic implant-supported fixed complete-arch prostheses: A cohort study with mean 5-year follow-up

STATEMENT OF PROBLEM

Long-term outcomes with metal-ceramic (MC) implant-supported fixed complete dental prostheses (IFCDPs) are scarce.

PURPOSE

The purpose of this retrospective study was to assess the rate of biologic and technical complications in a cohort of edentulous patients treated with MC IFCDPs by residents after a mean clinical follow-up of 5 years (range: 1 to 12 years).

MATERIAL AND METHODS

Forty-one participants with 55 MC IFCDPs underwent a single-visit comprehensive examination that included a medical and dental history review and clinical and radiographic examinations. All supporting implants and prostheses were examined for biologic and technical complications. Life table analysis and Kaplan-Meier survival curves were calculated.

RESULTS

Of 359 moderately rough surface dental implants, 2 had failed in 1 patient after 11 years of functional loading, yielding a cumulative implant survival rate of 99.4%. Owing to the implant failure, 1 of 55 edentulous arches restored with IFCDPs failed, yielding a cumulative prosthesis survival rate of 98.2% after mean observation period of 5.0 years. Soft tissue recession was the most frequent minor biologic complication (annual rate 7.8% at the prosthesis level) for both cement and screw-retained IFCDPs (group C and S), and peri-implantitis (annual rate 1.6% at the implant level) the most frequent major biologic complication. Wear of porcelain (annual rate 8.0% at the prosthesis level) was the most frequent minor technical complication for both groups, and fracture of porcelain (annual rate 0.8% at the dental-unit level) was the most frequent major technical complication. Minor complications were the most frequent in both the groups (cement and screw retained).

CONCLUSIONS

High implant and prosthesis survival rates (above 98%) were achieved, yet substantial complication rates were encountered. The most frequent major biologic complication was peri-implantitis, with a 5-year implant-based rate of 8% (95% confidence interval [CI]: 5.8-11.1), whereas the most frequent major complication was fracture of porcelain with a 5-year dental unit-based rate of 4%. The estimated cumulative rates for "prosthesis free of biologic complications" were 50.4% (95% CI: 36.4% to 63.0%) at 5 years and 10.1% (95% CI: 3.5% to 20.8%) at 10 years, whereas for "prosthesis free of technical complications," they were 56.4% (95% CI: 41.7% to 68.8%) at 5 years and 9.8% (95% CI: 3.2% to 21.0%) at 10 years.

Double Full-Arch Fixed Implant-Supported Prostheses: Outcomes and Complications after a Mean Follow-Up of 5 Years

PURPOSE

To retrospectively assess complications and clinical and radiographic outcomes of edentulous patients treated with double full-arch implant-supported fixed complete dental prostheses (IFCDPs) after a mean observation period of 5.1 years.

MATERIALS AND METHODS

The single-visit clinical and radiographic examination included medical and dental history review and clinical assessment of biologic and technical complications encountered with all implants and IFCDPs. Life table analysis and Kaplan-Meier survival curves were calculated. Analysis was conducted to evaluate the association between prosthesis survival and several risk factors such as type of opposing occlusion, nightguard use, and presence of bruxism.

RESULTS

Nineteen edentulous patients restored with 38 IFCDPs were included. A total of 249 implants were placed and 2 implants failed after a mean observation period of 5.1 years (range: 1-12 years), yielding an overall implant survival rate of 99.2% and prosthesis survival rate of 92.1%. Three out of 38 IFCDPs were lost, 1 after implant losses and 2 due to technical complications. The most frequent minor biologic complication was soft tissue recession with an estimated 5-year rate of 45.5% (95% CI: 39.4-57.5), while the most frequent major complication was peri-implantitis with an estimated 5-year implant-based rate of 9.5% (95% CI: 6.7-11.3). The most frequent minor technical complication was wear of the prosthetic material with an estimated 5-year rate of 49.0% (95% CI: 37.4-76.4), while the most frequent major technical complication was fracture of the prosthetic material with an estimated 5-year dental unit-based rate of 8.0% (95% CI: 6.6-10.1).

CONCLUSIONS

After a mean use time of 5.1 years, high implant and prosthesis survival rates were observed. The most frequent major biologic complication was peri-implantitis, and the most frequent major technical complication was fracture of the prosthetic material. The 5-year estimated cumulative rates for "prosthesis free of biologic complications" was 50.7% (95% CI: 33.7-65.4) and for "prosthesis free of technical complications" was 57.1% (95% CI: 39.3-71.5).

Effect of framework design and firing cycle on the success rate of bilayered zirconia crowns

OBJECTIVE

This study investigated the effect of framework design and modification of porcelain firing cycle on the occurrence of fractures of metal-ceramic and bilayered zirconia crowns after cyclic loading.

METHOD AND MATERIALS

Twenty-four zirconia crowns with two different apicocoronal incisal veneering porcelain lengths (ZS = 2.0 mm and ZL = 4.0 mm) were fabricated. Twenty-four metal-ceramic crowns with the same apicocoronal incisal veneering porcelain lengths (MS = 2.0 mm and ML = 4.0 mm) served as the control. All the specimens (n = 48) were thermally and mechanically cycle-loaded (49 N) for 1,200,000 cycles, and then evaluated for cracks and/or bulk fractures with an optical stereomicroscope (×10). In the second part of the study, the influence of firing cycle modification on the success rate of twenty-four bilayered zirconia crowns was also evaluated. Finally, two specimens from each group (n = 12) were sectioned and analyzed using a scanning electron microscope. Load-to-failure of the specimen that did not present bulk fracture was further assessed using a universal testing machine. Statistical analysis was performed with Fisher exact test and Kruskal-Wallis test.

RESULTS

A statistically significant lower occurrence of fractures (P < .05) was found after cyclic loading for bilayered zirconia versus metal-ceramic crowns. Modification of the firing cycle did not significantly influence the outcome after cyclic loading for zirconia bilayered crowns (P > .05).

CONCLUSION

Within the limitations of this study, porcelain-firing cycle with an extended cooling time did not appear to influence the occurrence of cracks and fractures of bilayered zirconia crowns.

Implant survival rates and biologic complications with implant-supported fixed complete dental prostheses: A retrospective study with up to 12-year follow-up

OBJECTIVES

To assess the rate of biologic complications and implant survival in edentulous patients treated with implant-supported fixed complete dental prostheses (IFCDPs) after a mean observation period of 5.2 years (range: 1-12 years).

MATERIALS AND METHODS

A single-visit clinical and radiographic examination was performed to assess types and rates of biologic complications with ceramic IFCDPs (Group 1) and metal-resin IFCDPs (Group 2).

RESULTS

Of 457 rough surface dental implants supporting 71 IFCDPs (52 patients), six had failed, yielding an implant survival rate of 98.7% after a mean observation period of 5.2 years after definitive prosthesis insertion. The most frequent minor biologic complication was soft tissue recession (7.7% annual rate), inflammation under the IFCDP (7.4% annual rate), and peri-implant mucositis (6.3% annual rate). The most frequent major biologic complication was peri-implantitis (2.0% annual rate), in 46/457 implants (10.1%) supporting 19 IFCDPs and late implant failure (0.3% annual rate). The frequency of biologic complications was not statistically different between Group 1 and Group 2. The presence of high plaque index had significant effect on bone loss.

CONCLUSIONS

After a mean exposure time of 5.2 years postdefinitive prosthesis insertion (range: 1-12 years), implant survival rate of 98.7% was achieved. The six implant failures in three patients occurred after 5 years and affected the prosthesis survival. Soft tissue recession was the most frequent minor biologic complication, whereas peri-implantitis was the most frequent major biologic complication. A 10-year implant-based mucosal recession rate of 77% (95% CI: 68.2-87.9) and a 10-year implant-based peri-implantitis rate of 20% (95% CI: 16.9-24.9) were found.

A meta-analysis of complications during sinus augmentation procedure

OBJECTIVE

The purpose of this systematic review was to assess the difference in the incidence of intraoperative and postoperative complications between the conventional and alternative surgical techniques, during sinus floor augmentation surgery.

DATA SOURCES

Electronic databases were searched for publications related to sinus floor augmentation surgery performed with different techniques (ie, conventional lateral window, piezosurgery, osteotome, trephine) and the incidence of complications. The articles were evaluated by independent reviewers, according to predetermined inclusion/exclusion criteria and processed for meta-analysis, following the PRISMA protocol. Initial search returned 3,940 articles, after inclusion/exclusion criteria, and quality assessment 11 articles were included in the meta-analysis: five randomized clinical trials and six retrospective studies. All the 11 included studies compared the incidence of complications in conventional lateral window sinus augmentation surgery versus alternative techniques, including: osteotome (five articles), piezosurgery (four articles), sonic surgery (one article), and trephine (one article). Meta-analysis of the incidence of intraoperative and postoperative complications during conventional lateral window sinus floor augmentation surgery versus alternative techniques, showed a significantly lower incidence of intraoperative complications for the retrospective studies. However, when data from the clinical trials alone were included in the meta-analysis, a statistically significant difference could not be detected for the incidence of intraoperative and postoperative complications.

CONCLUSIONS

The use of alternative techniques for sinus floor augmentation surgery (ie, piezosurgery, sonic surgery, osteotome, and trephine) does not necessarily reduce the incidence of intraoperative and/or postoperative complications compared to the conventional technique.

Multivariate evaluation of the cutting performance of rotary instruments with electric and air-turbine handpieces

STATEMENT OF PROBLEM

Laboratory studies of tooth preparation often involve single values for all variables other than the one being tested. In contrast, in clinical settings, not all variables can be adequately controlled. For example, a new dental rotary cutting instrument may be tested in the laboratory by making a specific cut with a fixed force, but, in clinical practice, the instrument must make different cuts with individual dentists applying different forces. Therefore, the broad applicability of laboratory results to diverse clinical conditions is uncertain and the comparison of effects across studies difficult.

PURPOSE

The purpose of this in vitro study was to examine the effects of 9 process variables on the dental cutting of rotary cutting instruments used with an electric handpiece and compare them with those of a previous study that used an air-turbine handpiece.

MATERIAL AND METHODS

The effects of 9 key process variables on the efficiency of a simulated dental cutting operation were measured. A fractional factorial experiment was conducted by using an electric handpiece in a computer-controlled, dedicated testing apparatus to simulate dental cutting procedures with Macor blocks as the cutting substrate. Analysis of variance (ANOVA) was used to assess the statistical significance (α=.05).

RESULTS

Four variables (targeted applied load, cut length, diamond grit size, and cut type) consistently produced large, statistically significant effects, whereas 5 variables (rotation per minute, number of cooling ports, rotary cutting instrument diameter, disposability, and water flow rate) produced relatively small, statistically insignificant effects. These results are generally similar to those previously found for an air-turbine handpiece.

CONCLUSIONS

Regardless of whether an electric or air-turbine handpiece was used, the control exerted by the dentist, simulated in this study by targeting a specific level of applied force, was the single most important factor affecting cutting efficiency. Cutting efficiency was also significantly affected by factors simulating patient/clinical circumstances and hardware choices. These results highlight the greater importance of local clinical conditions (procedure, dentist) in understanding dental cutting as opposed to other hardware-related factors.

Challenges in implant-supported dental treatment in patients with Sjogren's syndrome: A case report and literature review

Sjogren's syndrome (SS) is a systemic autoimmune disease that has several oral manifestations, with reduced salivary flow being the most prevalent. As a result of the dry mouth and irritated oral tissues, dental treatment may be challenging. In particular, a patient's satisfaction with removable prosthesis may be limited. This case report and the literature review discuss the feasibility of implant-supported dental prostheses. The clinical and functional advantages provided by implant prostheses might outweigh the slightly lower overall implant success rate in SS patients. The impacts of SS on dental treatment are summarized in this review.