Long-term survival and success of zirconia screw-retained implant-supported prostheses for up to 12 years: A retrospective multicenter study

Risk Factors for Early Implant Failure and Selection of Bone Grafting Materials for Various Bone Augmentation Procedures: A Narrative Review

Implant therapy is now an established treatment with high long-term success and survival rates. However, early implant failure, which occurs within one year of superstructure placement, occurs at a higher rate than late failure, which is represented by peri-implantitis caused by bacterial infection. Furthermore, various risk factors for early failure have been reported, including patient-related factors, such as systemic diseases, smoking, and bone quality and quantity, as well as surgery-related factors, such as surgeons' skill, osteogenesis technique, and selection of graft material, and implant-related factors, such as initial implant fixation and implant length diameter. Due to the wide variety of relevant factors reported, it is difficult to identify the cause of the problem. The purpose of this review is to discuss the risk factors associated with various types of bone augmentation which have a close causal relationship with early implant failure, and to determine the optimal bone grafting material for bone augmentation procedures to avoid early implant failure.

Accuracy of intraoral optical scan versus stereophotogrammetry for complete-arch digital implant impression: An in vitro study

PURPOSE

To assess and compare the accuracies of intraoral scanners (IOS) and stereophotogrammetry (SPG) devices for complete-arch digital implant impressions.

METHODS

A 4-analog model was digitized using a desk scanner to obtain a reference file. Thirty test scans were conducted using the investigated IOS device, while an additional 30 scans were performed using the SPG device. Using the best-fit algorithm, the resulting 60 test files were aligned with the reference file. Linear (ΔX, ΔY, and ΔZ-axis) and angular deviations (ΔANGLE) were evaluated. Three-dimensional (3D) deviation was calculated based on the Euclidean distance (ΔEUC). The analysis was stratified according to the scanning device and implant position. Fisher's F and t-tests were used to compare the variances and expected values of the two scanning systems.

RESULTS

IOS expressed a higher 3D (ΔEUC) mean deviation than SPG (52.8 µm vs. 33.4 µm, P < 0.0001), with extreme measurements up to 181.9 µm. A significantly higher standard deviation (SD) was associated with IOS (37.1 µm vs. 17.7 µm, P < 0.0001). Considering angular deviations, the IOS showed slightly higher angular mean deviations (ΔANGLE) than the SPG (0.28° vs. 0.24°, P = 0.0022), with extreme measurements of up to 0.73°. The SPG SD values were significantly lower than the IOS SD values (0.14° vs. 0.04°, P < 0.0001).

CONCLUSIONS

The SPG showed significantly higher 3D and angular accuracies for complete arch implant impressions, with consistent repeatability. IOS scanning revealed significantly higher extreme deviations exceeding the acceptable threshold value. Despite study limitations, SPG appears more feasible than IOS for complete-arch digital implant impressions.

Translucent monolithic zirconia titanium-supported FP1 full-arch prosthesis: A novel proof of concept to address esthetic, functional, and biologic challenges

OBJECTIVE

Despite the wide clinical use of translucent zirconia for full-arch implant prostheses, reduced flexural strength and fracture toughness compared with high-strength opaque zirconia needs to be addressed. A novel proof of concept for FP1 full-arch prosthesis featured by translucent monolithic zirconia and titanium framework was presented.

CLINICAL CONSIDERATIONS

Computer-guided implant planning and surgery were executed and digitally designed FP1 temporary prosthesis prefabricated. Implant and prosthetic placement were achieved with a set of three-dimensional (3D)-printed templates. Implants were immediately loaded. After 4 months intraoral optical scan was taken to record implant coordinates, soft tissue anatomy, and temporary FP1 prosthesis. A novel digital workflow was used to design and mill overlaying translucent zirconia and anatomically shaped titanium framework with a scalloped soft-tissue interface. Final FP1 prosthesis was assembled cementing zirconia jacket on titanium counterpart.

CONCLUSIONS

Translucent zirconia supported by titanium framework can address esthetic and mechanical requirements of FP1 full-arch prosthesis, minimizing risk of fracture and providing a rigid and passive joint with supporting implants. The smooth and highly polished titanium surface with an anatomic design, tightly matching scalloped soft tissue interface, can limit food impaction, air and saliva leakage and contribute to overall biologic integration of FP1 full-arch prosthesis.

CLINICAL SIGNIFICANCE

Translucent monolithic zirconia featured with anatomically shaped titanium framework with scalloped transmucosal part, combining a pleasant esthetic outcome with increased flexural strength and fracture toughness, may be indicated to increase the clinical performance of FP1 full-arch prosthesis.

One-piece versus two-piece zirconia abutment supported single implant crown in the esthetic region: 3-Year results from a split-mouth randomized controlled clinical trial

OBJECTIVES

To compare the clinical, radiographic, and immunological outcomes between one-piece versus two-piece zirconia abutments supported single implant crowns in the esthetic region.

MATERIALS AND METHODS

The study followed a split-mouth, double-blind, and randomized controlled clinical design for a duration of 3 years. Twenty-two eligible patients with 44 implants were randomly assigned to two groups: Group 1 (one-piece zirconia abutment with zirconia base, n = 22) and Group 2 (two-piece zirconia abutment with titanium base, n = 22). The primary outcome was the technical complication rate. Additionally, survival rates, cytokines concentrations in peri-implant crevicular fluid (PICF), peri-implant conditions, marginal bone loss, and pink/white esthetics score (PES/WES) were assessed as secondary outcomes.

RESULTS

Twelve of 22 patients attended the 1-year follow-up (due to the COVID pandemic), and 19 patients attended the 3-year examination. Two abutments in Group 1 were fractured after 10 and 12 months in function. Additionally, one screw loosening occurred in Group 1 at 1-year follow-up. The 3-year technical complication rate was significantly higher in Group 1 than that in Group 2 (15.79% vs. 0%, p < .001). The 3-year implant survival rate was 100% in both groups. The concentration of IFN-γ in PICF was significantly upregulated in Group 2 (p = .018). Furthermore, the IL-6 concentration was positively correlated with BOP% (p = .020).

CONCLUSIONS

Two-piece zirconia abutments exhibited superior technical performance compared to one-piece designs during a 3-year follow-up in the anterior region. However, further long-term research is necessary to verify the immunological stability of two-piece zirconia abutments.

Accuracy of complete-arch digital implant impression with intraoral optical scanning and stereophotogrammetry: An in vivo prospective comparative study

OBJECTIVES

To assess accuracy of intraoral optical scanning (IOS) and stereophotogrammetry (SPG), complete-arch digital implant impressions in vivo.

MATERIALS AND METHODS

Consecutive patients needing implant-supported screw-retained zirconia complete-arch fixed-dental prostheses (ISZ-FDP) were recruited. For each patient, three impressions were taken: IOS, SPG (tests), and open-tray plaster (reference). Linear (ΔX, ΔY, and ΔZ), three-dimensional (ΔEUC), and angular deviations (ΔANGLE) were evaluated and stratified according to scanning technology for each implant. Potential effects of impression device (IOS and SPG), arch (maxilla and mandible), and implant number (4 and 6) were evaluated through multivariable analysis. Significance level was set at .05.

RESULTS

A total of 11 complete arches (5 maxillae, 6 mandibles) in 11 patients were rehabilitated with ISZ-FDPs supported by 4 (n = 8) and 6 implants (n = 3). A total of 50 implants and 100 implant positions were captured by two investigated devices and compared to respective reference (mean ΔEUC IOS 137.2, SPG 87.6 μm; mean ΔANGLE 0.79, 0.38°). Differences between measurements (SPG-IOS) were computed for each implant, with negative values indicating better SPG accuracy. Significant mean ΔEUC difference of -49.60 μm (p = .0143; SD 138.15) and mean ΔANGLE difference of -0.40° (p < .0001; SD 0.65) were observed in favor of SPG. Multivariable analysis showed significant effect on ΔEUC (p = .0162) and ΔANGLE (p = .0001) only for impression devices, with SPG performing better.

CONCLUSIONS

SPG experienced significantly higher linear and angular accuracy. No effect of type of arch or implant number was detected. Higher extreme deviations were experienced for IOS. SPG can be feasible for complete-arch digital impressions with caution, and rigid prototype try-in is recommended before screw-retained prosthesis manufacturing.

Optimal impression materials for implant-supported fixed complete dentures: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Although polyvinyl siloxane (PVS) materials and polyether (PE) materials have been the recommended materials for making impressions for implant-supported fixed complete dentures (IFCDs), a consensus regarding the optimal impression materials has yet to be established.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate the effect of impression materials on the accuracy of conventional impressions for IFCDs and to provide guidance for selecting the optimal impression material.

MATERIAL AND METHODS

The PubMed, Web of Science, and Embase databases were searched and supplemented via hand searches. Studies comparing the accuracy of conventional impressions for IFCDs by using PVS and PE materials with either direct (open-tray) or indirect (closed-tray) techniques were included. Linear distance deviations and angular deviations between adjacent implants were evaluated. The mean difference (MD) with a 95% confidence interval (CI) was calculated for continuous data. A subgroup analysis was conducted to evaluate the impact of implant angulation (α=.05).

RESULTS

Among the 597 publications identified, 27 in vitro studies were included for qualitative analysis, and 12 were included for quantitative analysis. The general analysis revealed no significant differences in linear distance and angular deviations between the 2 impression materials with the direct or indirect technique. The subgroup analysis found that a statistically significant difference in linear distance deviations was found when implants were placed at an angle greater than 15 degrees, favoring PE materials when using the direct technique (P=.010, MD: 32.54 µm; 95% CI: 6.83 to 58.24) and indirect technique (P=.020, MD: 138.15 µm, 95% CI: 19.17 to 257.13). However, only 2 relevant studies assessed the indirect technique.

CONCLUSIONS

When providing IFCDs, conventional impressions obtained by using PVS and PE materials were found to have similar accuracy in most scenarios. PE materials yielded better outcomes when implants were placed at an angle greater than 15 degrees.

Evaluating the clinical behavior of veneered zirconia in comparison with monolithic zirconia complete arch implant-supported prostheses: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Because the use of zirconia in dentistry is relatively new, the number of published studies on the subject is scarce, even though material selection is an important factor in clinical performance. Therefore, a systematic assessment of the impact of the prosthetic material, framework design, veneering material, and manufacturing process is required.

PURPOSE

The purpose of this systematic review and meta-analysis was to investigate the survival and success rates of feldspathic porcelain veneered zirconia (VZir) in comparison with monolithic zirconia (MZir) complete arch implant-supported prostheses (CAISPs). A secondary objective was to assess the influence of the type of loading, the presence or absence of a cantilever, the type of zirconia used, the location, and the opposing arch on complications rates and patient satisfaction.

MATERIAL AND METHODS

An electronic search of the MEDLINE database (via PubMed), Scopus, Science Direct, Cochrane Library, and OpenGrey was carried out. The criteria described in the preferred reporting items for systematic reviews and meta-analyses statement were used. The search was restricted from January 2000 to January 2022.

RESULTS

The systematic search resulted in 20 articles that met the established criteria. In total, 751 patients (VZir=302; MZir=449) with 3038 CAISPs (VZir=368; MZir=2670) were analyzed. Higher prosthetic survival and success rates were found in MZir compared with VZir CAISPs (100% and 95.45%, respectively). The meta-analysis found significantly fewer complications related to MZir (9.4% [4.8%-14.1%]) compared with VZir (33.7% [17.5%-49.9%]).

CONCLUSIONS

Based on the findings of this systematic review, MZir CAISPs had higher survival and success rates than VZir CAISPs, with significantly fewer prosthetic complications. The influence of factors such as the type of functional loading, the presence of a cantilever, the material used in the prosthodontic workflow, the location of the CAISP, and the type of antagonist arch on the performance of Zir CAISPs remains unclear.

Mandibular Flexure and Its Significance: An In Vivo Cone Beam-Computed Tomography Proof-of-Concept Study

The aim of this study was to assess intra-arch mandibular dimensional changes that may occur during mouth opening using cone beam-computed tomography (CBCT). Fifteen patients in need of any type of treatment whose execution considered a pre- and post-CBCT assessment consented and were enrolled. CBCTs were taken with the following settings: 90 kV, 8 mA, field of view (FOV) 140 by 100 mm (height and diameter), Voxel size 0.25 mm (high resolution). The pre-CBCT was executed in the maximum mandibular opening (MO), while the post-CBCT was in the maximum intercuspation (MI). A thermoplastic stent with radiopaque fiducial markers (steel ball bearings) was fabricated for each patient. Measurements were made using radiographic markers between contralateral canines and contralateral first molars and between ipsilateral canines and first molars on both sides. Paired t-tests were performed to evaluate the difference between open and closed positions on these four measurements. In the MO position were registered a significative tightening of the mandible at the canine (-0.49 mm, SD 0.54 mm; p < 0.001) and molar points (-0.81 mm, SD 0.63 mm; p < 0.001) and a significative shortening of the mandible on the right (-0.84 mm, SD 0.80 mm; p < 0.001) and left sides (-0.87 mm, SD 0.49 mm; p < 0.001). Within the study limitations, mandibular flexure determined a significant shortening and tightening between maximum intercuspation to maximum opening positions. Mandibular dimensional changes should be considered in light of other patient factors in the treatment planning of implant positioning and long-span complete arch implant-supported fixed prostheses in order to avoid technical complications.

The Use of Zirconia for Implant-Supported Fixed Complete Dental Prostheses: A Narrative Review

The success of implant-supported fixed complete dental prostheses (ISFCDPs) depends on multiple factors: some are related to the fixtures, such as fixture material, surface characteristics, positioning, and type of connection to prosthetic components; others are related to the prostheses, such as design and materials used. Zirconia is a material widely used in fixed prosthodontics, whether on natural teeth or on implants, with excellent results over time. Regarding the use of zirconia for ISFCDPs, the 2018 ITI Consensus Report stated that "implant-supported monolithic zirconia prostheses may be a future option with more supporting evidence". Since CAD/CAM technology and zirconia are being continuously innovated to achieve better results and performances over time, a narrative review of the literature seems necessary to focus research efforts towards effective and durable solutions for implant-supported, full-arch rehabilitations. The objective of the present narrative review was to search the literature for studies regarding the clinical performance of zirconia-based ISFCDPs. According to the results of this review, the use of zirconia for ISFCDPs showed good clinical outcomes, with high survival rates ranging from 88% to 100% and prosthetic complications that were restorable by the clinicians in most cases.

Application in the analysis of the occlusal force of free-end missing tooth implant restoration with T-SCAN III

Introduction: The occlusal force of the teeth in the dental arch and the remaining adjacent natural teeth will change after implant restoration with a free-end missing tooth. This study intends to use the T-SCAN III scanner to collect dynamic quantitative data before and after the restoration of free-end implants and to explore the application of the T-SCAN III in redistributing the occlusal force of free-end implants.

Methods: In this study, 24 patients with free-end implant restoration were selected, and their occlusion was tested before, immediately after, and 3 months after implant restoration.

Results: In all 24 cases, the bite force of the first natural tooth adjacent to the implanted tooth after restoration changed from 19.12% ± 9.48%–12.93% ± 11.47% (p &lt; 0.01). For additional data analysis, all cases were further subdivided by single implant and fixed bridge restorations. In 17 cases, there was a successful follow-up after 3 months. The percentage of the total bite force of dental arch with implant increased from 41.92% ± 10.78%–53.06% ± 10.71% (p &lt; 0.01).

Discussion: This study shows that the free-end implant restoration protects the remaining natural teeth, and the patient’s missing dental arch bite force improves within 3 months of implant restoration.

Rehabilitation of Patients with Compromised Ridge Support Using Immediately Loaded Corticobasal Implant-supported Prostheses: A Prospective Observational Study

AIM

The aim of this prospective study is to evaluate the treatment outcomes and patient satisfaction following the use of fixed immediately loaded corticobasal implant-supported prostheses.

MATERIALS AND METHODS

One hundred and seventy-four corticobasal implants (basal cortical screw, BCS implant design) were inserted in 20 consecutive patients with compromised ridge support. Implant survival and success were assessed using the James-Misch implant health quality scale and the Albrektsson criteria for implant success. The peri-implant health was evaluated at 1 week and 3, 6, 9, 12, and 18 months postoperatively. Moreover, the radiographic and prosthetic parameters and patient satisfaction were assessed.

RESULTS

The implants showed optimum implant health and a 100% survival rate with none (0%) of the implants failing, mobile, lost, or fractured. Using Wilcoxon signed-rank test, significant decreases in both the modified gingival indexes and the probable pocket depth (PPD) and slight significant increases in the plaque index (PI) at 3, 9, 12, and 18 months and a nonsignificant increase at 6-month follow-up were reported with a range of 0-1. The calculus index (CI) was zero at all follow-up visits. Radiographic evaluations revealed increases in the bone-to-implant contact. Evaluation of the prostheses showed some treatable complications, and all the patients were satisfied.

CONCLUSION

The use of corticobasal implant-supported prosthesis meets the patient's demand for an immediate, fixed treatment modality, with high survival and success rates, optimum peri-implant soft tissue health, and high reported satisfaction.

CLINICAL SIGNIFICANCE

Corticobasal implants can improve the patient's esthetic, phonetic, mastication, and quality of life with the advantage of eliminating the need of bone grafting procedures.

Titanium Dental Implants: An Overview of Applied Nanobiotechnology to Improve Biocompatibility and Prevent Infections

This review addresses the different aspects of the use of titanium and its alloys in the production of dental implants, the most common causes of implant failures and the development of improved surfaces capable of stimulating osseointegration and guaranteeing the long-term success of dental implants. Titanium is the main material for the development of dental implants; despite this, different surface modifications are studied aiming to improve the osseointegration process. Nanoscale modifications and the bioactivation of surfaces with biological molecules can promote faster healing when compared to smooth surfaces. Recent studies have also pointed out that gradual changes in the implant, based on the microenvironment of insertion, are factors that may improve the integration of the implant with soft and bone tissues, preventing infections and osseointegration failures. In this context, the understanding that nanobiotechnological surface modifications in titanium dental implants improve the osseointegration process arouses interest in the development of new strategies, which is a highly relevant factor in the production of improved dental materials.

Selection of 1-mm venting or 2.5-mm screw access holes on implant crowns based on cement extrusion and retention capacity

Background

This in vitro study aimed to provide evidence regarding the selection of hole diameters of implant crowns to reduce excess cement extrusion at the abutment margin, and to examine the maintenance of their retention capacity in anterior and posterior cement-retained implant crowns.

Methods

Six groups of implant crowns were prepared according to the position of the teeth and the size of their holes as follows: anterior crown without hole (ANH), anterior crown with 1-mm mini venting hole (AMH), anterior crown with 2.5-mm regular screw access hole (ARH), posterior crown without hole (PNH), posterior crown with 1-mm mini venting hole (PMH), and posterior crown with 2.5-mm regular screw access hole (PRH). Temporary cement was used to bond the crowns to the abutments. The mean amount of excess cement extrusion among the different groups at the abutment margin was calculated. Retentive strength under different hole designs was measured as the dislocation force of the crown using a universal testing machine. One-way ANOVA and Welch’s t-test were used to analyze the results.

Results

The average amounts of extruded excess cement were 18.96 ± 0.64, 1.78 ± 0.41, and 1.30 ± 0.41 mg in the ANH, AMH, and ARH groups, respectively, and 14.87 ± 0.36, 1.51 ± 0.40, and 0.82 ± 0.22 mg in the PNH, PMH, and PRH groups, respectively. The hole opening in the crowns could significantly reduce residual cement regardless of its size (p < 0.001). The mean retentive strengths were 54.16 ± 6.00, 47.63 ± 13.54, and 31.99 ± 7.75 N in the ANH, AMH, and ARH groups, respectively, and 57.84 ± 10.19, 53.22 ± 6.98, and 39.48 ± 5.12 N in the PNH, PMH, and PRH groups, respectively. The retention capacity of the implant crown deteriorated rapidly as the holes on the crown surface enlarged.

Conclusions

The presence of a hole on the implant crown reduced the amount of excess cement. The retention ability of the implant crowns deteriorated as the size of the hole increased. Considering the esthetic effect of the crown and the possible influence on crown retention, an implant crown with a 1-mm mini venting hole is a better clinical choice than the one with a 2.5-mm regular screw access hole.

Navigation guided socket-shield technique for implant and pontic sites in the esthetic zone: A proof-of-concept 1-year prospective study with immediate implant placement and loading

OBJECTIVE

To assess clinical, radiological performance of novel navigation guided socket-shield technique (NSS) with immediate implant placement and loading.

MATERIALS AND METHODS

Eighteen patients (12 females; age 52.54 ± 4.92; 33-72) treated between January 2018 and June 2019, were investigated, and followed for at least 1 year after definitive prosthesis placement (mean 20.1 months, 18-23). Primary outcomes: implant and prosthetic success rates, surgical, biologic, prosthetic complications.

SECONDARY OUTCOMES

marginal bone loss (MBL), implant stability quotient (ISQ), pink esthetic score (PES), plaque and bleeding indexes.

RESULTS

Sixty-nine navigation guided socket-shield procedures were performed (27 implant-sites and 42 pontic-sites) and 27 implants (NobelParallel, NobelBiocare AG) positioned and immediately loaded. Mean insertion torque and ISQ at implant positioning were 49 ± 5.34 Ncm (36-74), 73 ± 5.72 (68-81). No implant failure was experienced. Two root-shield exposures with mucositis, ulceration and bleeding were reported at two pontic-sites (2.9%) and successfully treated. No complications were experienced at implant-site leading to an overall NSS success-rate of 100%. No prosthetic complications occurred. Mean MBL was -0.72 ± 0.26 mm (-0.42 to -1.06 mm). PES final at the last follow-up 12.84 ± 0.92. The plaque and bleeding scores were 18.5 ± 6.12 and 3.15 ± 2.21.

CONCLUSIONS

Within study limitations, dynamic navigation was effective to streamline execution of socket-shield technique at implant and pontic sites, shortening treatment time and reducing complications. Navigation guided socket-shield technique was reliable to achieve digitally planned shield-to-implant distance, facilitate immediate implant placement and loading and establish the mucosal dimension needed for underlying bone-to-implant protection and esthetic integration.

CLINICAL SIGNIFICANCE

The investigated NSS technique overcomes the difficulties related to root preparation at implant and pontic-sites, facilitating immediate implant placement and loading. Dynamic guided surgery contributed to make socket-shield technique less technical-sensitive, shortening time for execution, reducing complication rate.