Zirconia abutments: Biological, mechanical, and esthetic considerations – An umbrella review of available systematic reviews and meta-analyses

Evaluation of the peri-implant tissues in the esthetic zone with prefabricated titanium or zirconia abutments: A randomized controlled clinical trial with a minimum follow-up of 7 years

The aim of the present study was to give a detailed analysis on eight proposed implant esthetic indices including a total of 48 parameters with respect to validity and reproducibility as well as its correlation to patients' perception of esthetics. Standardized intraoral photographs of 189 patients with 189 implant-supported crowns and adjacent peri-implant soft tissue in the esthetic zone (central and lateral incisors, canine, first premolar) served as basis for this evaluation. Eight indices (Papilla Index [PI], Pink Esthetic Score [PES], Implant Crown Aesthetic Index [ICAI], Pink and White Esthetic Score [PES/WES], Complex Esthetic Index [CEI], Implant Aesthetic Score [IAS], Subjective Esthetic Score [SES], and Rompen Index) with a total of 48 parameters were selected. Esthetic evaluation was performed twice by five examiners with an interval of 4weeks between the evaluations. A total of 1,890 evaluations including eight esthetic indices served as basis for the statistical analysis. Among the overall main scores tested for inter-rater reliability, the highest values were computed for CEI, PES, PI, and IAS scores. By contrast, SES and Rompen showed the worst inter-rater reliability, respectively. The highest level of intra-rater reproducibility was noted for PI, PES, and CEI. The lowest level of intra-rater reproducibility showed Rompen, SES, and ICA. The Papilla Index demonstrated the highest level of inter-rater reliability. The remainder of the single variables (n=46) did not reach the level of 0.6. The single variables PI mesial, PI distal as well as CEI P4 showed the highest with statistical significance higher than 0.8. The lowest agreement was observed among the variables ICA3, WES5, and IASm2. In general, VAS did not show any good correlation to the esthetic indices proposed so far. The influence of esthetic parameters on subjective patient satisfaction was generally low. In conclusion, significant differences regarding reliability and validity could be observed in the present comparison of eight esthetic indices. Objective evaluation of the esthetic outcome of implant therapy inherently fails to reflect subjective patient opinion, however, requires consistency of results to enable between-study comparison and meta-analysis.

The primary objective was to provide an overview of soft tissue metric parameters, methods, and aesthetic indices in implant dentistry. The secondary objective was to describe reliability and validity of aesthetic indices. Two independent reviewers conducted an electronic literature search in Pubmed, Web of Science, Embase, and Cochrane databases up to October 2020 to identify studies on soft tissue metric parameters, methods, and aesthetic indices. Aesthetic indices were evaluated in terms of reliability and validity. Data extraction was performed by the same reviewers. Five metric parameters (papilla height, linear changes in soft tissue level, color assessment, soft tissue thickness, and profilometric soft tissue changes) registered by means of several methods (intra-oral registrations, radiographic assessments, digital analyses, and ultrasonic assessments), and 15 aesthetic indices (Papilla Index (PI), ad hoc questions scored with Visual Analogue Scales, Pink Esthetic Score (PES), Implant Crown Aesthetic Index (ICAI), Implant Aesthetic Score (IAS), Rompen Index, Subjective Esthetic Score, White Esthetic Score, Copenhagen Index, Complex Esthetic Index, Californian Dental Association Index (CDAI), Peri-Implant, and Crown Index, Functional Implant Prosthodontic Score, Implant Restoration Esthetic Index (IREI), and Mucosal Scarring Index (MSI)) could be identified. With respect to metric parameters and methods, intra-oral registrations were least accurate whereas profilometric soft tissue changes on the basis of digital surface models were most accurate. Six aesthetic indices showed good inter-rater reliability (PI, PES, ICAI, CDAI, IREI, and MSI). Good validity could only be shown for two indices (PES and CEI). Given this and on the basis of ease of use and ease of interpretation, PES qualified best for clinical research on single implants. None of the indices fulfilled the quality criteria for clinical research on multiple implants. Many soft tissue assessment methods with varying reliability and validity have been described and used, which hampers uniform reporting in implant dentistry. Clinical investigators are advised to measure linear and profilometric soft tissue changes using digital surface models, and to use a reliable and validated aesthetic index. Currently, PES qualifies best for aesthetic evaluation of single implants. An index is to be developed to assess the aesthetic outcome of rehabilitations on multiple implants.

To compare five different implant treatment protocols in the anterior maxilla, including immediate, early, and delayed implant placement, as well as implant placement in conjunction with simultaneous guided bone regeneration and implant placement 3 months following horizontal autologous bone block grafting. Aesthetic indices used included the Pink Esthetic Score (PES), Papilla Index (PI), Subjective Esthetic Score (SES), and White Esthetic Score (WES). Subjective evaluation of implant aesthetics was performed using a visual analogue scale (VAS). The VAS consisted of a 10 cm-long line representing the degree of discontent (0%) or satisfaction (100%). A total of 153 implants in 153 patients (80 women, 73 men) were evaluated after a mean follow-up of 4.5 ± 2.9 years. Mean peri-implant bone loss was 1.6 ± 0.9 mm and not affected by treatment protocol, time after implant placement, or crown length. Papilla presence, by contrast, differed significantly between the protocols: Papilla formation was more pronounced following delayed and immediate implant placement. No statistical significance was found among treatment modalities with regard to PES, SES, or WES. Longer crowns were associated with lower PES and PI ratings and correlated with greater midfacial recession. SES was also influenced by time after implant placement and keratinized mucosa. Patient satisfaction differed significantly among treatment protocols, favoring immediate implant placement. Agreement between objective and subjective aesthetic ratings was low. The present study suggests that comparable clinical, radiological, and aesthetic results can be achieved with all treatment protocols. Gingival recession, however, seems to occur in the long term irrespective of the technique used.

The aim of this study was to test whether zirconia abutments exhibit the same clinical and esthetic outcomes as titanium abutments in single-tooth implant restorations in the esthetic area. The 24 treated patients were randomly assigned to a test (zirconia abutment) or control (titanium abutment) group. Objective evaluations were carried out using the Implant Crown Aesthetic Index (ICAI) and the Papilla Index (PI) at the 1-month and 12-month follow-up examinations after crown cementation. No significant differences, either in ICAI or in other periodontal or radiographic measurements, were observed. At 1 year, zirconia and titanium abutments exhibited the same esthetic outcomes.

ABSTRACTObjectiveThis study aimed to compare the technical and biological complications of single implants with veneered porcelain on either titanium or zirconia abutments after 10 years in function.Materials and MethodsAll single‐implant surgeries performed at a specialist prosthodontic clinic between 2011 and 2013 were reviewed. After applying the inclusion criteria, 174 implants in 132 patients were included for further analysis. Marginal bone loss relative to baseline and technical complications, including porcelain fractures, were recorded from patient data.ResultsA total of 65 patients with 87 implants were followed until the 10‐year evaluation, including 29 implants connected to a veneered zirconia abutment and 58 to a veneered titanium abutment. One implant with a zirconia abutment was lost due to peri‐implantitis after 7 years, while all other implants survived. Marginal bone loss did not differ significantly between the two abutment groups. At 10 years, implants with titanium abutments showed a mean marginal bone loss of 0.31 mm, whereas implants with zirconia abutments had a mean marginal bone loss of 0.28 mm. Peri‐implant mucositis was observed in 34% of implants with zirconia abutments, compared to 16% of those with titanium abutments. Technical complications were noted in 10.3% of the implants at the 10‐year follow‐up. The most common complication was the chipping of the veneering porcelain, followed by abutment screw loosening.ConclusionImplant survival did not differ significantly between the two veneered abutment materials. Both abutment types exhibited low marginal bone loss at the 10‐year follow‐up. However, peri‐implant mucositis was more frequently observed around zirconia abutments. Technical complications were moderate, primarily presenting as chipping of the veneering porcelain. The success rate for implants with zirconia abutments was 93%, compared to 82% for those with titanium abutments.

Today there are several treatment techniques available to replace a missing tooth. Since the beginning of the 1990s, it has become increasingly common to treat individual tooth loss with dental implants. Important patient factors are survival, success, functionality, aesthetics, oral health and quality of life. The range of indications and possibilities for implant treatment has broadened compared to the originally proposed treatment indications. A variety of methods, components and materials are available today. Improvements of the implant surface have led to shorter healing periods, which has affected the overall treatment time. Methods for computer-assisted implant planning and surgical guides have been developed to improve treatment planning. Several techniques are involved in the manufacturing of implant-supported single crowns, from the traditional plaster models, wax, casting and porcelain veneering to 3D scanning, computer aided design and manufacturing. It is important that all these treatment modalities are evaluated in a systematic and scientific way to ensure that the treatment given is the best one possible according to the individual conditions that exist. The general aim of this project was to evaluate the treatment outcome between different treatment modalities for single dental implants. Study I aims to retrospectively evaluate implant survival. Patient reported outcome measures, marginal bone loss (MBL), clinical and esthetic outcomes following conventional single implant treatment. The aim of study II, a prospective randomized clinical study, was to compare the overall treatment outcome following immediate loading (IL) and delayed loading (DL) of single implants. In study III the aim was to in a vitro setting evaluate the deviation in final dental implant position after the use of surgical guides fabricated from two different desktop 3D printers using a digital workflow. For study IV the aim was to, in a non-randomized study, compare clinical and aesthetic outcomes between immediately loaded single implants placed with and without a fully guided-surgery procedure (DIL). In study I a total of 85 implants were examined after a mean follow-up time of 7.51 years. The 5-year implant survival rate was98.4% (95% CI: 96.3% - 100%), with a crown survival rate of91.8% (95% CI: 86.3%-97.3%). Overall mean MBL was -0.13 mm. Final and initial total Pink esthetic score (PES) were 9.61 and 11.49 (P<.001) Mean White esthetic score (WES) was 6.48 at final follow-up. Visual analog scale (VAS) score for soft tissue and implant-supported crown aesthetics were 73.5 and 82.1 (maximum score 100). A oral health impact profile-14 (OHIP-14) 14 score of 16.11 was observed at the final follow-up. Study II and IV found implant survival rates of 100%, 96% and 90.5 % for IL, DL and DIL, respectively, after 1-year. No statistically significant differences were found for MBL, PES, WES and OHIP-14after 1-year. Statistically significant lower papilla index scores were found for the IL. Overall statistically significant improvement inPES, WES and OHIP-14 were found over time. In the DIL group a moderate correlation between aesthetics and deviation in fixture position was found. For Study III a statistically significant difference between stereolithography and direct light processing (DLP) was found fordeviation at entry point (P = .023) and the vertical implant position(P = .009). Overall lower deviations were found for the guides from the DLP printer, with the exception of deviation in horizontal implant position.The results from these studies suggest that good clinical results can be achieved with different treatment modalities for single implants. Positive advantages with immediate loading and guided surgery is primarily seen in the early faces of the treatment procedure only. Care needs to be exerted with technically complicated treatment procedures as the effect on implant survival should not be underestimated. Further studies have to be performed to evaluate guided surgery and immediate loading to identify possible factors effecting survival.

Objective To compare the influence of platform switching or regular platform implants on radiographic and aesthetic outcome in the maxillary anterior zone. Methods Patients who had received single implant in the anterior maxilla from 2013 to 2016 in Hospital of Stomatology, Sun Yat-sen University were enrolled. A total of 24 patients receiving 25 implants meeting the inclusion criteria were recruited and divided into two groups: platform-switching interface group (n= 12) and matching butt-joint interface group (n= 13) . The overall mean follow-up period was 14 months. Photographs were taken and the aesthetic outcome was assessed according to pink esthetic score and white esthetic score (PES and WES) and marginal bone loss (MBL) was measured with standardized digital intra-oral radiographs. Non parametric variables were statistically analyzed with Mann-Whitney U-test. Results The survival rate of implants in both the two groups was 100%. MBL in the platform switching group (0.38 ± 0.39) mm was less than that in the platform matching group (0.98 ± 0.48) mm, which was statistically different (U= 133.5, P= 0.002) . According to the professional assessments, PES in platform switching group was 9.33 ± 2.61, while PES in platform matching group was 8.15 ± 1.73, which was not statistically different (U= 52.5, P= 0.168) . WES in platform switching group was 6.83 ± 1.59, while WES in platform matching group was 7.15 ± 2.58, which was not statistically different either (U= 92.5, P= 0.437) . Conclusions Platform witching and regular platform implants yielded high survival rate and comparable aesthetic outcome in the maxillary anterior zone. MBL in platform switching group was less than that in platform matching group. Key words: Esthetics, dental; Bone resorption; Platform switching, dental implant; Pink esthetic score; White esthetic score

The aim of this systematic review was to evaluate the influence of zirconia and titanium as abutment materials on peri-implant soft tissue color. The searched electronic databases included MEDLINE/PubMed, LILACS, Web of Science, Scopus, and LIVIVO. Two types of studies were included: randomized clinical trials (RCTs) and controlled clinical trials (CCTs) that compared zirconia (Zr) and titanium (Ti) abutments. The outcomes measured were as follows: implant crown esthetic index, visual analog scale, esthetic index, gingiva discoloration index-spectrophotometry, papilla index, recession index, and pink esthetic score. Two reviewers selected the records, assessed quality, and extracted data of included studies independently. A total of 323 patients enrolled in 13 studies were included in this analysis with 11 RCTs and 2 CCTs. Due to the wide variety of methodologies used, meta-analysis was only possible for RCTs that performed spectrophotometric analysis. The use of zirconia or titanium for implant abutments does not seem to be the principal factor for influencing peri-implant soft tissue color. The meta-analysis showed no difference between zirconia and titanium abutments. This study does not support any better advantage of the use of zirconia in comparison to the use of titanium related to peri-implant tissue color.

Patients’ esthetic expectations are increasing, and the options of the prosthetic pathways are currently evolving. The objective of this randomized multicenter clinical trial was to assess and compare the esthetic outcome and clinical performance of anterior maxillary all-ceramic implant crowns (ICs) based either on prefabricated zirconia abutments veneered with pressed ceramics or on CAD/CAM zirconia abutments veneered with hand buildup technique. The null hypothesis was that there is no statistically significant difference between the 2 groups. Forty implants were inserted in sites 14 to 24 (FDI) in 40 patients in 2 centers, the Universities of Bern and Geneva, Switzerland. After final impression, 20 patients were randomized into group A, restored with a 1-piece screw-retained single crown made of a prefabricated zirconia abutment with pressed ceramic as the veneering material using the cut-back technique, or group B using an individualized CAD/CAM zirconia abutment (CARES abutment; Institut Straumann AG) with a hand buildup technique. At baseline, 6 mo, and 1 y clinical, esthetic and radiographic parameters were assessed. Group A exhibited 1 dropout patient and 1 failure, resulting in a survival rate of 94.7% after 1 y, in comparison to 100% for group B. No other complications occurred. Clinical parameters presented stable and healthy peri-implant soft tissues. Overall, no or only minimal crestal bone changes were observed with a mean DIB (distance from the implant shoulder to the first bone-to-implant contact) of −0.15 mm (group A) and 0.12 mm (group B) at 1 y. There were no significant differences at baseline, 6 mo, and 1 y for DIB values between the 2 groups. Pink esthetic score (PES) and white esthetic score (WES) values at all 3 examinations indicated stability over time for both groups and pleasing esthetic outcomes. Both implant-supported prosthetic pathways represent a valuable treatment option for the restoration of single ICs in the anterior maxilla (ClinicalTrials.gov NCT02905838).

Mechanical behavior of titanium and zirconia abutments at the implant-abutment interface: A systematic review

Long-Term Survival and Peri-Implant Health of Titanium Implants with Zirconia Abutments: A Systematic Review and Meta-Analysis.

The aim of this study was to compare the effect of different surface treatments applied to short titanium and zirconia abutments on the bond strength of single-unit zirconia crowns. Sixty titanium abutments were shortened to 3 mm in length, fixed to analogs, and embedded in acrylic blocks. Three-dimensional views of abutments were obtained by scanning; then, zirconia abutments and copings were produced. The samples, which included titanium (n = 60) and zirconia (n = 60) abutments, were divided into five different groups (n = 12), and surface treatments were carried out; 1.5-W and 3-W Er,Cr:YSGG laser treatment, AL2O3 sandblasting, and tribochemical silica coating were applied to the groups, and the control group had no surface treatment. Copings were cemented to the samples with self-adhesive resin cement. The samples were then subjected to the pull-out test, and the results were processed via statistical analysis. There was a significant difference between the titanium and zirconia groups (P < .001). The mean bond strength values of the titanium samples were higher than those of the zirconia samples. The tribochemical silica coating gave a higher bond strength than the other treatments when applied to titanium abutments. For the zirconia abutments, the 1.5-W laser treatment, 3-W laser treatment, tribochemical silica coating, and Al2O3 sandblasting groups differed significantly from the control group; however, they were not significantly different from each other. The bond strength of zirconia crowns to short titanium and zirconia abutments increases with surface treatments. Furthermore, the surface treatments were more effective in increasing the bond strength for the titanium abutments than for the zirconia abutments.

Evaluation of the sealing capability of implants to titanium and zirconia abutments against Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum under different screw torque values

To address the following question: "Is the timing of implant placement and/or loading influencing the esthetic outcomes of implant-supported single crowns?" A literature screening was performed in four electronic databases until June 2020. Randomized controlled clinical trials with a minimum of 10 patients and 1year of follow-up and reporting on dimensional changes of the peri-implant mucosa (midfacial recession, papilla level) and esthetic indexes were included. Cochrane Risk of Bias Tool was used, and comparable trials were subjected to meta-analyses. Out of 8549 articles, 72 full-text articles were assessed for eligibility and 18 were included. Nine trials evaluated the timing of implant placement, and nine trials evaluated the timing of loading. The included trials comparing immediate implant placement to delayed implant placement evaluating the midfacial recession reported heterogeneous findings. No differences were found at 1 and 2-years, when comparing midfacial recession and papilla level between immediate and early implant placement. In immediate and delayed implant placement, when comparing conventional and immediate loading, the midfacial mucosal margin change was not statistically significant at the 1-year follow-up. When evaluating the timing of implant placement and/or loading the included trials found no differences in the Pink Esthetic score, White Esthetic score, and Papilla Index between groups. Both immediate and early implant placement protocols presented stable treatment results in terms of esthetic outcomes at the 1-, 2-, and 10-years follow-up. Loading protocols did not seem to influence esthetic outcomes in short- and medium-term follow-ups.