THE EFFECT OF DIFFERENT SUPERSTRUCTURE MATERIALS OF IMPLANT SUPPORTED RESTORATION. A SYSTEMATIC REVIEW.

e (n = 95 ) Full-text articles assessed for


Search methods for identification of studies:-Electronic databases searches:-
The resulting inclusion criteria (table 1) were obligatory to: complication of implant supported restoration (biological complication), articles published in English. Case report, case study, invitro study, article in press and animal studies articles were excluded (table2).
To identify the research question, the PubMed database, the Cochrane and ovoid databases were searched electronically. Databases were searched for articles from 2000 through October 2017 using the next (MeSH) terms: implant superstructure (b) implants crown (c) zirconia implant superstructure (d) All ceramic implant superstructure (e) metallic implant superstructure (f)titanium implant superstructure (g) periodontal loss (h) periodontal pocket (i) periodontal pocket index, (j) alveolar bone loss (k) rescission and the combinations. Other applicable non-MeSH words were used in the search to recognize articles showing periodontal inflammatory parameters. These included -yettria-stabilized zirconia abutment‖ -zirconia implant superstructure‖ -inflammation implant superstructure‖ -bleeding index implant superstructure‖ and -peri-implant pocket‖ and -clinical attachment loss around implant abutment.‖ The studies collected after the 1072

Data collection and analysis:-Study selection:-
The 144 articles were screened independently by two reviewer (M.M, A.M) through titles and abstracts. articles that meet the inclusion criteria and that have no sufficient data to take optimum choice, the full text was gotten. The full reports that are collected from the different electronic and hand searching were checked independently by two authors (M.M, N.F) to get an absolute decision of whether these articles met the inclusion criteria or not. Disagreements were resolved among authors by open discussion; where a third review author (M.M, N.F, A.M) was a consulted and firmness was not possible, 26 studies meet the inclusion criteria, data extraction were done under constant protocol. Studies rejected at this stage or following stages were collected. A table for the excluded studies  and the reasons for exclusion was reported. (table 3).
Data extraction:-Independently using constant designed data extraction forms fourteen studies undergo data extraction by two review authors (M.M, M.R). Data extraction were shown and modified on several papers before agreement to use. Any disagreement among author were debated in open discussion and a review author (N.F) consulted was essential. Data of disagreement were excluded until clarification was presented. For each study, the extracted data was listed as follow ( Missing data Protocol: -Efforts was done to regain missing data from trials authors. and if cross-sectional data were accessible; Change data can be done, the standard deviation -SD‖ of the changes was to be assessed using the no. within patient correlation, which will give information to the conservative estimate of the SD for change. This technique was described by Follmann (13). To guess the standard error of the difference for split mouth studies when the proper data were not accessible and could not be found.

Heterogeneity Assessment:-
Cochran's test for heterogeneity was used to assess the significance of any differences. heterogeneity would have been considered significant if P < 0.1. All 14 included studies results were pooled using the random model effect as statistical heterogeneity among studies was significance where (I4 = 93% P <0.00001).

Results:-
A total of twenty-six studies  of implant single crown superstructure were included in this study. The analyzing data of the selected studies are described in Table 1. All the studies were published from 2000-2017. In nineteen studies (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) the implants were placed by means of a standard surgical protocol in a healed normal implant site of bone Type III or IV. an ‗early' implant placement in two studies (Type II) was performed and immediate implant placement in other three studies (Type I) was done. some special issues were addressed in Several studies, such as early implants loaded after only six weeks or immediate implants loading immediately, Also, two studies informed on small-implants diameter, where the diameters ranged of 3 mm to 2.9 mm and used to support Single crown superstructure. 1076 The studies were directed in an official environment, such as medical universities or implant specialized clinics. Two of the included studies were done in multi-clinic studies. The twenty-six studies  involved of a total of 1530 single crown superstructure. Twenty-six of the included studies reported on implant superstructures material, 80% of the implant superstructures were metal-ceramic, 15% were all-ceramic implant superstructures while the rest were of gold-acrylic design. Only 10% of the implant superstructures were screw retained and 90% were cemented retained implant superstructures ( Table 2).
The effect of superstructure materials:-Single crown superstructures survival was defined as the Single crown superstructures lasting in situ with or without complication for the observation period. after a mean follow-up time of 5 years, thirteen studies ( with a total number of 534 Single crown superstructures gives data on the survival of the superstructures (Table 4). Fifteen out of the thirty-three Single crown superstructures were lost while the supporting implants were lost but in the lasting eighteen cases only the superstructures failed. The rate of failure per 100 Single crown superstructures years have ranged from 0 to 2.19 (Fig. 3). according to the superstructures material the studies were also divided utilized: a group of 7 studies with a total of 236 porcelain fused to metal crowns and a group of 2 studies with a total of 162 nonmetallic ceramic crowns. The group with porcelain fused to metal crowns showed a significantly higher survival rate. Peri-implantits were reported in 10 studies as Biological complications but in several ways by the different authors. Two studies used the universal term of ‗soft tissue complications'; ‗signs of inflammation' were reported in four other studies as probing pocket depth combined with bleeding on probing, and Gotfredsen et al. described cases with ‗soft tissue dehiscence.' Other studies described on fistula formation. In ten studies, radiographic analysis used to evaluate the marginal bone height.

Discussion:-
Survival rate of crowns on single implant supported tooth was documented to be high in 5 years period in addition to, increase in technical and biological complications. In case of absence of single tooth many treatments can restore it such as implant supported single tooth restoration, conventional fixed partial denture or cantilevered fixed partial denture. (25) RCTs are seemed to be of high evidence level to contrast between different treatment patterns. consequently, obscurity of RCTs in comparing these various treatment patterns will lead to depreciation the evidence level. i.e. in this systematic review retrospective and prospective studies were involved. a tremendous importance clinically was to contrast and evaluate wide range of treatment patterns as to select the most suitable treatment for patient advice. More over, the on top systematic reviews were accomplished according to the same standards. Containing retrospective and prospective studies with a perception time not less than five years. however, It can be contended that a subsequent time of five years is too short to get dependable data on survival rates and intricacy rates. (30,31) Ways that all studies were incorporated into this review is releasing with in the most recent ten years and more than 33% inside the most recent two years shows that the utilization of dental implants to help single crowns is generally recent. Henceforth, a follow-up time of no less than five years was an important trade off. Conversely, ten years contemplates on the life span of traditional fixed partial dentures go back to the 1990s. Subsequently, alert must be practiced in the correlation of technical complications (i.e., veneer cracks) of regular FPDs made over twenty years prior and implant supported single crowns made five to ten years back. Most of the examinations on ordinary fixed partial dentures investigated gold-acrylic fixed partial dentures while the implant-supported single crowns are for the mostly made of metal-ceramic. (40) The survival of superstructure materials:-After five years the survival rate of single crowns on implants became 94.5% inside this study. This evidence derived from 13 research which include 534 implant-supported single crowns. A very similar survival percentage was verified after five years of 95% (95% CI: 92.2-96.8%) in evaluating 1289 implant supported fixed partial dentures. (33,34) with the intention to contrast the adverse remedy modalities for a missing single tooth, the final results for the implant-supported single crowns need to be compared with the outcomes of conventional fixed partial dentures and cantilever fixed partial dentures. contrasting the rate of survival after five years, the values for the implant-supported single crowns are very much like the ones from the conventional fixed partial denture and slightly better in comparison with the cantilever fixed partial dentures. (31) 1077 in the next five years duration the percentage of failure of the implant supported fixed partial dentures and the Cantiliver fixed partial dentures have raised according to Pjetursson et al. (28,29) Consequently, it would be of terrific significance to collect long-time period records for the implant-supported single crowns. The existing study additionally evaluated the impact of the crown material on the survival rate. It became verified that metallic-ceramic crowns (95.4%) showed a statistically notably higher survival rate in contrast with all-ceramic crowns (91.2%). Moreover, studies comparing the final results of metal ceramic crowns with the all ceramic crowns in the same study were absent in this review. (24) The values for all-ceramic implant crowns inside this research had been much like the values of a current systematic review examining all-ceramic crowns on tooth abutments (Wassermann et al.) (26) In 12 incorporated research, In cream Alumina crowns of 1724 were determined over a minimal duration of 1-3 months as much as a maximum period of 100 months. Survival rates ranged from 86.5% to 100%. With the Kaplan-Meier approach for the In-ceram Aluminia crowns the cumulative survival rate was of 92% after five years. Biological complications, peri-implant mucosal lesions (9.7% after 5 years) seems to be the most common biological complications for implant-supported single crowns. consequently, this value is similar to the pooled cumulative survival rate of biological complications after five years [8.6% (95% CI: 5.1-14.1%)] for patients handled with implant-supported fixed partial denture. inside the current study, it was documented that the crown layout (screw-retained vs. cemented) had no effect on the biological complications. This finding may be in understanding with a clinical study assessing the peri-implant microflora of implants for cemented and screw-retained superstructures. It might have been finished up that those sway of the dental microflora on the microbial colonization of the implants shows to be more significant over the mode of stabilization of the superstructure. (19,20) Analyzing implant-supported single crowns with tooth-supported fixed partial denture, the tooth supported fixed partial denture indicated increased biological complications.
it was stated that about 9.1-9.5% of the abutment teeth contained caries after 10 years. In addition to, about 10% of the abutment tooth loss its vitality in the same 10 years period (36) . Also, the remedy of the peri-implant mucosal lesion my be less time consuming and less technique sensitive when compared with the treatment of non-vital or carious tooth.