The Influence of Vertical Implant Position With Immediate Provisionalization on the Marginal Bone Loss.

Multiple clinical studies have established high survival rates and tremendous predictability of dental implant treatment. However, a pleasant esthetic outcome is the patient's primary expectation regarding implants in the esthetic zone and several esthetic factors have been evaluated to contribute to an esthetic appearance. Among these, the midfacial soft tissue level is considered to be one of the most important factors; Cosyn and co-workers reported that among factors including soft tissue phenotype, the midfacial recession was associated with the position of the implant . Therefore, subcrestal implant placement has been advocated as it has been associated with the reduction of crestal bone loss in cases with decreased soft tissue thickness. If the vertical soft tissues on the crest of the alveolar ridge are 2 mm or less at the time of implant placement, implants will undergo unavoidable bone resorption by establishing sufficient biologic protection. Another option was proposed by Linkevicius et al, who introduced the subcrestal implant placement as a method to accommodate the problem of thin soft tissues. Research question: Does the placement of delayed implants with different vertical depth affect the marginal bone loss with immediate provisionalization?

Preservation of crestal bone is crucial and must be prioritized from the onset of implant placement. Adequate amount of peri-implant bone contributes to esthetic success and implant stability. Crestal bone contributes to both esthetics and function. Resorption of crestal bone is seen as loss of interproximal papillary support and gingival recession, which gives way to peri-implantitis and compromises esthetics. With respect to the depth of insertion, implants can be placed at various levels in the bone, in which affects the peri-implant tissues with the surrounding marginal bone. Therefore, Placement of an implant in a deeper position with re¬spect to the bone crest (subcrestal placement) has been suggested as a method that could contribute to main¬tain the periimplant soft and hard tissues in comparison with crestal placement, though this affirmation is sub¬ject to controversy. Rationale for conducting the research: Limiting the extent of peri-implant bone loss has been recognized for decades to be an important aspect of long-term implant success, and stable peri-implant bone conditions play an important role in maintaining esthetics. the opinion expressed widely in the scientific literature has been that subcrestal implant placement leads to increased crestal bone resorption. However, clinical studies addressing the implant placement depth in relation to crestal bone have been rare. Data on subcrestal versus crestal placement have mostly come from animal studies. Even fewer data are available regarding the effects of crestal versus subcrestal positioning of platform-switched implants. In a prospective research, Nagarajan et al. implanted equicrestal and subcrestal implants to examine the crestal bone levels prior to loading. The crestal bone levels of the implants placed equicrestally (1.31 mm 1.04 mm and 0.68 mm 1.08 mm on mesial and distal surfaces, respectively) were higher than those of implants placed subcrestally (0.49 mm 0.49 mm and 0.025 mm 6.06 mm on mesial and distal surfaces, respectively), with a P value of crestal bone level for both groups being 0.12 and 0. They came to the conclusion that there was no difference in the amount of crestal bone loss prior to prosthetic loading between implants placed at subcrestal and equicrestal levels. In this study eqi-crestal implant will be used as a comparator but with immediate loading.