Production time, effectiveness and costs of additive and subtractive computer-aided manufacturing (CAM) of implant prostheses: A systematic review.

OBJECTIVE: To systematically review the dental literature for clinical studies reporting on production time, effectiveness and/or costs of additive and subtractive computer-aided manufacturing (CAM) of implant prostheses. MATERIALS AND METHODS: A systematic electronic search for clinical studies from 1990 until June 2020 was performed using the online databases Medline, Embase and Cochrane. Time required for the computer-aided design (CAD) process, the CAM process, and the delivery of the CAD-CAM prostheses were extracted. In addition, articles reporting on the effectiveness and the costs of both manufacturing technologies were included. RESULTS: Nine clinical studies were included reporting on subtractive CAM (s-CAM; 8 studies) and additive CAM (a-CAM; 1 study). Eight studies reported on the s-CAM of prosthetic and auxiliary components for single implant crowns. One study applied a-CAM for the fabrication of an implant bar prototype. Time was provided for the CAD process of implant models (range 4.9-11.8 min), abutments (range 19.7-32.7 min) and crowns (range 11.1-37.6 min). The time for s-CAM of single implant crown components (abutment/crown) ranged between 8.2 and 25 min. Post-processing (e.g. sintering) was a time-consuming process (up to 530 min). At delivery, monolithic/veneered CAD-CAM implant crowns resulted in additional adjustments chairside (51%/93%) or labside (11%/19%). CONCLUSIONS: No scientific evidence exists on production time, effectiveness and costs of digital workflows comparing s-CAM and a-CAM. For both technologies, post-processing may substantially contribute to the production time. Considering effectiveness, monolithic CAD-CAM implant crowns may be preferred compared to veneered CAD-CAM crowns.

Digital technique for in vivo assessment of internal and marginal fit of fixed dental prostheses.

Digital approaches to assess the misfit of fixed dental prostheses have been limited to in vitro evaluation. The present article describes a fully digital technique for the in vivo assessment of the fit of fixed dental prostheses by means of a chairside optical scanner and software for 3-dimensional (3D) analysis. The 3D digital capture is performed in 3 steps: an extraoral scan of the restoration, an intraoral scan of the abutment tooth, and an intraoral registration scan of the restoration positioned on the abutment tooth.

Digital technologies to support planning, treatment, and fabrication processes and outcome assessments in implant dentistry. Summary and consensus statements. The 4th EAO consensus conference 2015.

OBJECTIVE: The task of this working group was to assess the existing knowledge in computer-assisted implant planning and placement, fabrication of reconstructions applying computers compared to traditional fabrication, and assessments of treatment outcomes using novel imaging techniques. MATERIAL AND METHODS: Three reviews were available for assessing the current literature and provided the basis for the discussions and the consensus report. One review dealt with the use of computers to plan implant therapy and to place implants in partially and fully edentulous patients. A second one focused on novel techniques and methods to assess treatment outcomes and the third compared CAD/CAM-fabricated reconstructions to conventionally fabricated ones. RESULTS: The consensus statements, the clinical recommendations, and the implications for research, all of them after approval by the plenum of the consensus conference, are described in this article. The three articles by Vercruyssen et al., Patzelt & Kohal, and Benic et al. are presented separately as part of the supplement of this consensus conference.

Randomized controlled multicentre study comparing short dental implants (6 mm) versus longer dental implants (11-15 mm) in combination with sinus floor elevation procedures. Part 1: demographics and patient-reported outcomes at 1 year of loading.

AIM: To test whether or not the use of short dental implants (6 mm) results in an implant survival rate similar to long implants (11-15 mm) in combination with sinus grafting. METHODS: This multicentre study enrolled 101 patients with a posterior maxillary bone height of 5-7 mm. Patients randomly received short implants (6 mm) (group short) or long implants (11-15 mm) with sinus grafting (group graft). Six months later, implants were loaded with single crowns and patients re-examined at 1 year of loading. Outcomes included treatment time, price calculations, safety, patient-reported outcome measures (OHIP-49 = Oral Health Impact Profile) and implant survival. Statistical analysis was performed using a non-parametric approach. RESULTS: In 101 patients, 137 implants were placed. Mean surgical time was 52.6 min. (group short) and 74.6 min. (group graft). Mean costs amounted to 941EUR (group short) and 1946EUR (group graft). Mean severity scores between suture removal and baseline revealed a statistically significant decrease for most OHIP dimensions in group graft only. At 1 year, 97 patients with 132 implants were re-examined. The implant survival rate was 100%. CONCLUSIONS: Both treatment modalities can be considered suitable for implant therapy in the atrophied posterior maxilla. Short implants may be more favourable regarding short-term patient morbidity, treatment time and price.

In vitro assessment of artifacts induced by titanium, titanium-zirconium and zirconium dioxide implants in cone-beam computed tomography.

AIM: The aim of this study was to test whether or not the intensity of artifacts around implants in cone-beam computed tomography (CBCT) differs between titanium, titanium-zirconium and zirconium dioxide implants. MATERIALS AND METHODS: Twenty models of a human mandible, each containing one implant in the single-tooth gap position 45, were cast in dental stone. Five test models were produced for each of the following implant types: titanium 4.1 mm diameter (Ti4.1 ), titanium 3.3 mm diameter (Ti3.3 ), titanium-zirconium 3.3 mm diameter (TiZr3.3 ) and zirconium dioxide 3.5-4.5 mm diameter (ZrO3.5-4.5 ) implants. For control purposes, three models without implants were produced. Each model was scanned using a CBCT device. Gray values (GV) were recorded at eight circumferential positions around the implants at 0.5 mm, 1 mm and 2 mm from the implant surface (GVT est ). GV were assessed in the corresponding volumes of interest (VOI) in the control models without implants (GVC ontrol ). Differences of gray values (ΔGV) between GVT est and GVC ontrol were calculated as percentages. One-way ANOVA and post hoc tests were applied to detect differences between implant types. RESULTS: Mean ΔGV for ZrO3.5-4.5 presented the highest absolute values, generally followed by TiZr3.3 , Ti4.1 and Ti3.3 implants. The differences of ΔGV between ZrO3.5-4.5 and the remaining groups were statistically significant in the majority of the VOI (P ≤ 0.0167). ΔGV for TiZr3.3 , Ti4.1 and Ti3.3 implants did not differ significantly in the most VOI. For all implant types, ΔGV showed positive values buccally, mesio-buccally, lingually and disto-lingually, whereas negative values were detected mesially and distally. CONCLUSIONS: Zirconium dioxide implants generate significantly more artifacts as compared to titanium and titanium-zirconium implants. The intensity of artifacts around zirconium dioxide implants exhibited in average the threefold in comparison with titanium implants.

In vitro assessment of artifacts induced by titanium dental implants in cone beam computed tomography.

OBJECTIVE: The objective of this study was to evaluate the geometric pattern and the intensity of artifacts around titanium implants in cone beam computed tomography (CBCT) using an in vitro model. MATERIAL AND METHODS: Ten test models, each containing one 4.1-mm-diameter titanium implant, were cast from a human mandible using silicone impression material and dental stone. Each model contained an implant in one of the following single-tooth gaps: 37, 36, 34, 33, 31, 41, 43, 44, 46, and 47. For control purposes, three models without implants were produced. Each model was scanned five times using a CBCT scanner. Gray values (GV) were recorded at eight circumferential positions around the implants at 0.5 mm, 1 mm, and 2 mm from the implant surface (GVTest ). GV were measured in the corresponding volumes of interest (VOI) in the models without implants (GVControl ). Differences of gray values (ΔGV) between GVTest and GVControl were calculated as percentages. To detect differences between GVTest and GVControl , the 95% confidence interval (CI) was computed for the values of ΔGV. Repeated measures ANOVA was used for the comparison of ΔGV at 0.5 mm, 1 mm, and 2 mm from the implant surface. RESULTS: Artifacts reflected by altered GV were always present in the proximity of titanium implants, regardless of the implant position. When comparing GVTest and GVControl , increased GV were found at the buccal and lingual aspects of the implant sites, whereas regions with reduced GV were located along the long axis of the mandibular body of the test models. A significant decrease in artifact intensity was found with increasing distance from the buccal implant surface (ΔGV0.5 mm : 45 ± 10% [SD], ΔGV1 mm : 28 ± 14% [SD], ΔGV2 mm : 14 ± 7% [SD]) (P < 0.001). CONCLUSION: Artifacts around titanium implants in CBCT images were distributed according to a geometrical pattern.

Systematic review of parameters and methods for the professional assessment of aesthetics in dental implant research.

OBJECTIVE: The purpose of the present systematic review was to evaluate the scientific literature regarding the professional assessment of aesthetics in implant dentistry. MATERIAL AND METHODS: An electronic search of Medline database and Cochrane Central Register of Controlled Trials was performed, and complemented by a manual search. Clinical or validation studies (Part 1) and randomized-controlled trials (RCTs) (Part 2) reporting parameters and methods for the assessment of aesthetics were included. The information regarding the assessment of aesthetics was extracted. The methodological quality of RCTs was evaluated by means of the Cochrane Collaboration's Tool for assessing risk of bias. RESULTS: The search yielded 149 and 32 publications in Part 1 and Part 2, respectively. A great diversity with regard to parameters, methods and measurement units used for the assessment of aesthetics was found among the included studies. With respect to time points of assessment there were significant differences between the RCTs. Only two RCTs fulfilled all the criteria of the The Cochrane Collaboration's Tool for assessing risk of bias. CONCLUSIONS: Due to the differences of the study designs, parameters and methods used for the assessment of aesthetics, comparisons between studies should be interpreted with caution. Only a limited number of RCTs offer sound evidence on aesthetic outcomes in implant dentistry.

Assessment of the potential of growth factors for localized alveolar ridge augmentation: a systematic review.

OBJECTIVE: To systematically assess the literature regarding the clinical, histological, and radiographic outcome of bone morphogenetic proteins (BMP-2, BMP-7), growth/differentiation factor-5 (GDF-5), platelet-derived growth factor (PDGF), and parathyroid hormone (PTH) for localized alveolar ridge augmentation. MATERIAL AND METHODS: Five separate Medline searches were performed in duplicate for human and animal studies, respectively. The primary outcome of the included studies was bone regeneration of localized alveolar ridge defects or craniofacial defects. RESULTS: In six human studies, BMP-2 affected local bone augmentation with increasing volume for higher doses. A majority (43 of 45) of animal studies using BMP-2 showed a positive effect in favour of the growth factor (GF). In six of eight studies, a positive effect was associated with the use of BMP-7. Only one animal study was included for GDF-5 revealing statistically significantly higher bone volume. Regarding PDGF, statistically significantly higher bone volume was observed in five of 10 included studies. Four animal studies using PTH revealed statistically significantly more bone regeneration compared with controls. CONCLUSIONS: Differing levels and quantity of evidence were noted to be available for the GFs evaluated, revealing that BMP-2, BMP-7, GDF-5, PDGF, and PTH may stimulate local bone augmentation to various degrees. Human data for the potential of rhBMP-2 are supportive.