Digital workflow: In vitro accuracy of 3D printed casts generated from complete-arch digital implant scans.

STATEMENT OF PROBLEM: Data on the accuracy of printed casts from complete-arch digital implant scans are lacking. PURPOSE: The purpose of this in vitro study was to compare the 3D accuracy of printed casts from a complete-arch digital implant intraoral scan with stone casts from conventional impressions. MATERIAL AND METHODS: An edentulous mandibular cast with 4 multiunit abutments with adequate anteroposterior spread was used as the master cast. Digital scans (n=25) were made by using a white light intraoral scanner (IOS). The generated standard tessellation language (STL) data sets were imported into a computer-assisted design (CAD) software program to generate complete-arch implant casts through 3D printing technology. The 25 printed casts and the mandibular master cast were further digitized by using a laboratory reference scanner (Activity 880; Smart Optics). These STL data sets were superimposed on the digitized master cast in a metrology software program (Geomagic Control X) for virtual analysis. The root mean square (RMS) error and the average offset were measured. RESULTS: When compared with the master cast, the printed casts had a mean ±standard deviation RMS error of 59 ±16 µm (95% CI: 53, 66). The maximum RMS error reached 98 µm. The average offsets were all negative, with a significant difference compared with zero (P<.001). CONCLUSIONS: The implant 3D deviations of the printed casts from complete-arch digital scans had statistically significant differences compared with those of the master cast but may still be within the acceptable range for clinical application.

Differences in micromorphology of the implant-abutment junction for original and third-party abutments on a representative dental implant.

STATEMENT OF PROBLEM: Evidence for micromorphology and precision of fit of third-party prosthetic components compared with the original manufacturer's components is lacking. PURPOSE: The purpose of this in vitro pilot study was to evaluate the micromorphological differences among different commercial brands of zirconia, titanium, and gold abutments for dental implants in terms of tight surface contact. MATERIAL AND METHODS: The following abutments (n=3 per type) were preloaded on Straumann Bone Level implants according to the manufacturer's instructions for zirconia (Zr, Zr2, Zr3), titanium (Ti and Ti2), and gold (Gold 1, Gold 2). The micromorphology of the implant-abutment units was investigated by using scanning electron microscopy (original magnification ×10 to ×500) after microtome sectioning. After we calibrated, the length of the areas with tight contact (TC) (discrepancy ≤3 µm) was calculated at the level of conical connection (CC), lower internal connection (LIC), and screw threads (STs). The interexaminer agreement was assessed by using intraclass correlation coefficient(s) (ICC). One-way ANOVA was used for the overall comparison of the Zr groups, and the Student paired t test was used for pairwise comparisons of the abutments of the same group. After we adjusted for multiple comparisons, the significance level for the overall and pairwise comparisons of Ti and Gold groups was set at a P value of .008 and a P value of .003 for the Zr groups. RESULTS: Major differences were found among the different abutment types in terms of design and extent of surface contact. The TC showed significant differences among the abutments of Zr group, depending on the side and level of evaluation (Zr1 > Zr2 > Zr3 on the left side for CC; Zr1, Zr2 > Zr3 on the right side for CC, and, Zr2 > Zr3 on the right side for LIC; P<.003). In Ti group, no significant differences were found (P>.008). The Gold and Gold 2 groups had significantly greater contact on the left side of CC (P<.008). CONCLUSIONS: A difference in design of the abutments was apparent. The tight surface contact was significantly different among the examined abutments or abutment screws and the respective area of the inner surface of the implants.

Complete mouth rehabilitation and gastroesophageal reflux disease: Conventional and contemporary treatment approaches.

This report describes the diagnosis and prosthodontic management of 2 patients with a history of chronic gastroesophageal reflux disease and worn dentition. Different treatment approaches were used for oral rehabilitation. Use of conventional and contemporary restorative materials resulted in functional and esthetic prosthodontic rehabilitation with a favorable prognosis.

Evaluation of Surface Roughness of Ceramic and Resin Composite Material Used for Conservative Indirect Restorations, after Repolishing by Intraoral Means.

PURPOSE: To evaluate and compare the mean surface roughness (Ra) of one ceramic and one resin composite material used for indirect restorations, after grinding and repolishing by intraoral means. MATERIALS AND METHODS: The materials used were the lithium disilicate glass ceramic IPS e.max Press (EMP) and the indirect resin composite restoration system Gradia (GR). Twelve specimen disks were prepared from each material according to the manufacturer of each material. Five initial measurements of the Ra (Ra1 ) were made on each specimen as a referral basis, and the specimens were ground with a fine (red) diamond bur. The specimens were repolished using (a) Komet Dialite Polishing Kit for EMP and (b) Enhance Finishing and Polishing System and Prisma Gloss Polishing Paste for GR. Five final Ra (Ra2 ) measurements were performed on each specimen. All measurements were made using a laser profilometer. Scanning electron microscopy (SEM) was also used to visualize the initial surface morphology and the morphological changes on the specimens' surface after repolishing. RESULTS: A highly significant difference was found between Ra1EMP and Ra2EMP (p < 0.001), between Ra1GR and Ra2GR (p < 0.001), as well as between Ra2EMP and Ra2GR (p < 0.001), when compared in pairs. A highly significant difference (p < 0.001) was also found between ΔRaEMP and ΔRaGR , with ΔRaGR being higher than ΔRaEMP . The RaGR values were higher than the RaEMP values at all times. SEM revealed that both EMP and GR repolished surfaces presented with irregularities; however, in GR specimens major voids and craters were present. CONCLUSIONS: EMP was found to perform better when polished by intraoral means compared with GR. Both materials exhibited Ra2 above the critical threshold for increased plaque accumulation and periodontal inflammation. If enamel-to-enamel roughness found in occlusal contact areas is considered as baseline, both materials were clinically acceptable after repolishing.

Full-arch implant fixed prostheses: a comparative study on the effect of connection type and impression technique on accuracy of fit.

PURPOSE: The aim of this study was to assess the effect of connection type and impression technique on the accuracy of fit of implant-supported fixed complete-arch dental prostheses (IFCDPs). MATERIALS AND METHODS: An edentulous mandibular cast with five implants was fabricated to serve as master cast (control) for both implant- and abutment-level baselines. A titanium one-piece framework for an IFCDP was milled at abutment level and used for accuracy of fit measurements. Polyether impressions were made using a splinted and non-splinted technique at the implant and abutment level leading to four test groups, n = 10 each. Hence, four groups of test casts were generated. The impression accuracy was evaluated indirectly by assessing the fit of the IFCDP framework on the generated casts of the test groups, clinically and radiographically. Additionally, the control and all test casts were digitized with a high-resolution reference scanner (IScan D103i, Imetric, Courgenay, Switzerland) and standard tessellation language datasets were generated and superimposed. Potential correlations between the clinical accuracy of fit data and the data from the digital scanning were investigated. To compare the accuracy of casts of the test groups versus the control at the implant and abutment level, Fisher's exact test was used. RESULTS: Of the 10 casts of test group I (implant-level splint), all 10 presented with accurate clinical fit when the framework was seated on its respective cast, while only five of 10 casts of test group II (implant-level non-splint) showed adequate fit. All casts of group III (abutment-level splint) presented with accurate fit, whereas nine of 10 of the casts of test group IV (abutment-level non-splint) were accurate. Significant 3D deviations (P < 0.05) were found between group II and the control. No statistically significant differences were found between groups I, III, and IV compared with the control. Implant connection type (implant level vs. abutment level) and impression technique did affect the 3D accuracy of implant impressions only with the non-splint technique (P < 0.05). CONCLUSION: For one-piece IFCDPs, the implant-level splinted impression technique showed to be more accurate than the non-splinted approach, whereas at the abutment-level, no difference in the accuracy was found.

Transition from failing dentition to complete-arch implant rehabilitation with a staged approach: a 3-year clinical report.

The transition of patients from failing dentition to complete-arch implant rehabilitation often means that the patient is rendered edentulous and has to wear a removable complete denture for a time. Many patients find this objectionable. A staged treatment approach provides a fixed interim prosthesis for use throughout the rehabilitation process, allowing patient comfort and prosthodontic control. This clinical report describes a staged approach protocol with a new type of interim prosthesis. The prosthesis is supported by hopeless teeth and the soft tissues of the maxillary tuberosities and mandibular retromolar pads for the complete-arch implant rehabilitation of a patient with failing dentition. This protocol allows for a fixed interim prosthesis with combined tooth and mucosa or implant support during the entire rehabilitation process, thus avoiding the use of complete dentures. The implants and prostheses were functioning successfully after 3 years of clinical service.

Reversible, non-plaque-induced loss of osseointegration of successfully loaded dental implants.

OBJECTIVES: Excess loading has been often cited as a reason for the failure of dental implants or bone loss post-osseointegration. The available data from animal studies have failed to show a clear role for excessive loading in the loss of osseointegration. The present case documentations aimed at providing a deeper insight into the medium- to long-term influence of occlusal loading on osseointegrated implants, and describe the clinical manifestations of such pathology. MATERIAL AND METHODS: Two cases of loss of osseointegration are documented with single implants in the posterior maxilla. Implant mobility was in both cases the first and only sign of pathology, with the absence of plaque-induced inflammation and marginal bone loss. RESULTS: Re-osseointegration of the implants was achieved after the removal of the prosthetic reconstruction. CONCLUSIONS: The two cases reported that the loss of osseointegration in the absence of plaque-induced peri-implant inflammation is possible, although the clinical manifestations were very different to these of peri-implantitis. Once the occlusal loading was withdrawn, re-osseointegration was clinically confirmed in a period of 6-8 months.

Implant and prosthodontic survival rates with implant fixed complete dental prostheses in the edentulous mandible after at least 5 years: a systematic review.

BACKGROUND: The treatment of mandibular edentulism with implant fixed complete dental prostheses (IFCDPs) is a routinely used treatment option. PURPOSE: The study aims to report the implant and prosthodontic survival rates associated with IFCDPs for the edentulous mandible after an observation period of a minimum 5 years. MATERIALS AND METHODS: An electronic MEDLINE/PubMED search was conducted to identify randomized controlled clinical trials and prospective studies with IFCDPs for the edentulous mandible. Clinical studies with at least 5-year follow-up were selected. Pooled data were statistically analyzed and cumulative implant- and prosthesis survival rates were calculated by meta-analysis, regression, and chi-square statistics. Implant-related and prosthesis-related factors were identified and their impact on survival rates was assessed. RESULTS: Seventeen prospective studies, including 501 patients and 2,827 implants, were selected for meta-analysis. The majority of the implants (88.5% of all placed implants) had been placed in the interforaminal area. Cumulative implant survival rates for rough surface ranged from 98.42% (95% confidence interval [CI]: 97.98-98.86) (5 years) to 96.86% (95% CI: 96.00-97.73) (10 years); smooth surface implant survival rates ranged from 98.93% (95% CI: 98.38-99.49) (5 years) to 97.88% (95% CI: 96.78-98.98) (10 years). The prosthodontic survival rates for 1-piece IFCDPs ranged from 98.61% (95% CI: 97.80-99.43) (5 years) to 97.25% (95% CI: 95.66-98.86) (10 years). CONCLUSION: Treatment with mandibular IFCDPs yields high implant and prosthodontic survival rates (more than 96% after 10 years). Rough surface implants exhibited cumulative survival rates similar to the smooth surface ones (p > .05) in the edentulous mandible. The number of supporting implants and the antero-posterior implant distribution had no influence (p > .05) on the implant survival rate. The prosthetic design and veneering material, the retention type, and the loading protocol (delayed, early, and immediate) had no influence (p > .05) on the prosthodontic survival rates.

Accuracy of implant impressions for partially and completely edentulous patients: a systematic review.

PURPOSE: To compare the accuracy of digital and conventional impression techniques for partially and completely edentulous patients and to determine the effect of different variables on the accuracy outcomes. MATERIALS AND METHODS: An electronic and manual search was conducted to identify studies reporting on the accuracy of implant impressions. Pooled data were descriptively analyzed. Factors affecting the accuracy were identified, and their impact on accuracy outcomes was assessed. RESULTS: The 76 studies that fulfilled the inclusion criteria featured 4 clinical studies and 72 in vitro studies. Studies were grouped according to edentulism; 41 reported on completely edentulous and 35 on partially edentulous patients. For completely edentulous patients, most in vitro studies and all three clinical studies demonstrated better accuracy with the splinted vs the nonsplinted technique (15 studies, splint; 1, nonsplint; 9, no difference). One clinical study and half of the in vitro studies reported better accuracy with the open-tray vs the closed-tray technique (10 studies, open-tray; 1, closed-tray; 10, no difference). For partially edentulous patients, one clinical study and most in vitro studies showed better accuracy with the splinted vs the nonsplinted technique (8 studies, splint; 2, nonsplint; 3, no difference). The majority of in vitro studies showed better accuracy with the open-tray vs the closed-tray technique (10 studies, open-tray; 1, closed-tray; 7, no difference), but the only clinical study reported no difference. CONCLUSION: The splinted impression technique is more accurate for both partially and completely edentulous patients. The open-tray technique is more accurate than the closed-tray for completely edentulous patients, but for partially edentulous patients there seems to be no difference. The impression material (polyether or polyvinylsiloxane) has no effect on the accuracy. The implant angulation affects the accuracy of implant impressions, while there are insufficient studies for the effect of implant connection type. Further accuracy studies are needed regarding digital implant impressions.

Tooth- and tissue-supported provisional restorations for the treatment of patients with extended edentulous spans.

UNLABELLED: Dental implants have been used successfully for decades in the treatment of edentulous patients and offer great comfort compared with complete dentures. However, completely edentulous patients or patients with several teeth with poor prognosis that will be all extracted have to be provided with an interim complete denture until the implants have been uncovered. Complete dentures are a less attractive option for the patients because of functional, esthetic, and psychological reasons. The use of complete dentures over implants during the patients' healing period has been associated with numerous complications. The aim of this paper was to present a new type of provisional restoration supported by hopeless teeth and soft tissues. CLINICAL SIGNIFICANCE: These provisional restorations can be used during the osseointegration period to avoid the use of a complete denture. The teeth can thus be restored with fixed restorations during the whole osseointegration period to provide better comfort and avoid the psychological stress of using a removable prosthesis. Additionally, the problems associated with dentures over implants or grafts (pressure, implant exposure, etc.) can be eliminated.