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Purpose: The objectives of this review were to (1) identify if prosthodontic parameters influence the esthetic outcome of implant-supported restorations and (2) make clinically relevant recommendations based upon the findings. Materials and Methods: Electronic and manual searches of dental literature were performed to collect information on esthetic outcomes based on objective criteria. The prosthodontic parameters included optimal three-dimensional implant position, the utilization of provisional restorations, the timing of provisional restoration with regard to implant placement, the choice of prosthodontic platform size and form, the abutment and definitive restoration material, and the mode of prosthesis retention. Regions including maxillary and mandibular anterior teeth and premolars were considered. All levels of evidence, including case studies, were accepted. Results: From 472 titles, 152 full-text articles were evaluated and 58 records included for data extraction (15 randomized controlled trials, 6 cohort studies, and 37 case series studies). Considerable heterogeneity in study design was found. A meta-analysis of controlled studies was not possible. It was consistently reported that facial malpositioning of implants increases the likelihood of mucosal recession. No studies directly compared esthetic outcomes associated with the use or non-use of provisional restorations. The literature contains a greater number of case series studies evaluating esthetic outcomes for protocols including, rather than excluding, provisional restorations. It is not possible to identify any significant variation in esthetic outcomes based on the character of the abutment platform from the current literature. Based on the findings, no significant difference can be established between all-ceramic and metal-ceramic prostheses with regard to esthetic indices over short observation periods. No firm conclusions relating esthetic benefits for cement in comparison to screw retention can be identified. Conclusions: There is a need for RCTs comparing accepted procedures in routine practice. The utilization of provisional restorations remains strongly recommended in order to trial the planned definitive restoration, to facilitate maturation of healing tissues and for patient convenience. Implant positioning according to the planned prosthesis remains a requirement to achieve a long-lasting esthetic outcome. The majority of studies reported on single-tooth replacement, and many of the outcomes may not be relevant or applicable to the large number of esthetic indications involving more than one tooth. Keywords: abutment material, final restoration material, implant position, implant restoration mode of retention, implant-supported provisional restoration, restorative implant platform size and form, timing of provisional restoration

Purpose: Excess residual cement around the implant margin has been shown to be detrimental to the peri-implant tissue. This in vitro study examines the retentive strengths of two different cementing techniques and two different luting agents on a machined titanium abutment and solid screw implants. The amount of reduction of excess cement weight between the two cementation techniques was assessed. Materials and Methods: Forty gold castings were fabricated for 4.1 mm in diameter and 10 mm in length solid-screw dental implants paired with 5.5-mm machined titanium abutments. Twenty implants received a provisional cement, and 20 implants received a definitive cement. Each group was further divided into two groups. In the control group, cement was applied and the castings seated over the implant-abutment assembly. The excess cement was then removed. In the study group, a "practice abutment" was used to express excess cement prior to cementation. The weight of the implant-casting assembly was measured and the residual weight of cement was calculated. The samples were then stored for 24 hours at 100% humidity prior to tensile strength testing. Results: Statistical analysis revealed significant differences in tensile strength across the groups. Further Tukey tests showed no significant difference in tensile strength between the practice abutment technique and the conventional technique for both definitive and provisional cements. There was a significant reduction in residual cement weight, irrespective of the type of cement, when the practice abutment was used prior to cementation. Conclusions: Cementation of implant restorations on a machined abutment using the practice abutment technique and definitive cement may provide similar uniaxial retention force and significantly reduced residual cement weight compared to the conventional technique of cement removal. Keywords: cementation, dental cement, dental implants, tensile strength

Purpose: The aim of this review was to determine the effect of several potential local risk factors on implant survival and success (primary outcomes) as well as on mucosal recession, bleeding on probing, and proximal marginal bone loss (secondary outcomes). Materials and Methods: A comprehensive review of the literature was conducted. The selection of publications reporting on human clinical studies was based on predetermined inclusion criteria and was agreed upon by three reviewers. After title and abstract screening of 2,681 publications obtained from the search, 19 articles were deemed to be relevant to the topic and the search criteria. Results: Limited data show that when an implant is placed within 3 mm of the neighboring tooth, proximal bone is at risk. The data regarding the placement of implants into infected sites are still insufficient, but studies have shown that this may be possible. Soft tissue thickness has not been shown to be a risk factor in implant survival. There is also no evidence to support a relationship between the width of keratinized tissue and implant survival. No studies were found that directly related bone density to implant survival. Implant stability was also difficult to examine due to the lack of validated stability measures. Discussion and Conclusion: One critical factor that faced the group during the review of the literature and interpretation of the data was the multifactorial nature of implant therapy. This makes isolation of specific risk factors difficult. Conclusions are limited by the current lack of quality clinical trials in this area. Keywords: dental implants, hard tissue, infection, interdental space, local risk factors, soft tissue

Purpose: Screw retention is recommended for implant supported and retained prostheses in the anterior maxilla. This is because machined components have improved fit charactersitics and excess cement removal is difficult when restorative margins are located greater than 2mm subgingivally. Recently, in order to increase predictability of an aesthetic result, restorative options have increased. The use of screw-retained customized abutments in conjunction with cement retained crowns is one of these options. This procedures is associated with several advantages. Machined components can be utilized deep in the ginigival sulcus and the cement line is moved coronally where it is readily accessible. The use of customized abutments also increases the degree of flexibility for the oro-facial implant axis, as restorative inclination can be modified in the abutment.It is common for the oro-facial implant axis to change between screw and cement retention. In other words, the oro-facial implant axis needs to be set up toward palatal side of the incisal edge for a screw retained implant prosthesis. On the other hand, the oro-facial implant axis of cement retained implant prostheses requires an implant axis that passes through the incisal edge. This gives a more ideal emergence profile and improves cement line location. The difference between these axes influences traditional contour (particularly emergence) of the prosthesis. Therefore, it is possible that differences the oro-facial implant axis (and the use of this inclination as a measureable parameter) may help in obtaining and predicting aesthetic treatment results. For this study, the angle between planned implant axis for screw and cement retention was measured using the Cone-Beam CT (CBCT) images. Materials and Method: Adequate bone volume in the anterior maxilla is necessary for optimal restoration-based implant placement. Measurements were initially performed using CBCT images of maxillary central incisal areas characterized by an absence of periodontal disease or prosthesis. The angle formed between the axis of an implant planned for cement retention (Point A), and the axis of an implant planned for screw retention (Point B) was measured. Furthermore, the distance between the buccal alveolar crest (point C) and the palatal alveolar crest (point D) was measured. Result and Conclusion: The oro-facial implant axis of implants planned for screw and cement retained prostheses was examined using the CBCT images of the normal maxillary central incisor region. Proceedings of the 3rd ITI Consensus Conference identified the optimal three-dimensional implant position. Accordingly, when the implant axis for screw retention inclines unfavorably in comparison to the implant axis for cement retention, the prosthesis tends to become a ridge-lap design with aesthetic compromise. The tolerance level of this angle made between implant axes planned for screw and cement retention is one of the important factors for ensuring a satisfactory emergence profile and optimal aesthetic result. Keywords: Oro-facial Implant Axis, Anterior Maxilla, Cone-beam CT