Long-Term Marginal Bone Stability of BOPT Restorations on Bone-Level vs. Tissue-Level Implants: An 8-Year Prospective Clinical Study
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Published on: February 10, 2014
M-A Navarro-Moxica1, M García-Selva, A Roig-Vanaclocha
1Marina García Selva Faculty of Medicine and Dentistry (Unit of Prosthodontics and Occlusion). Universitat de València, C/ Gascó Oliag, 1. 46010 Valencia, Spain. marina.garcia@uv.es.
Background:
The Biologically Oriented Preparation Technique (BOPT) has been applied to implant-supported restorations to promote peri-implant tissue stability. However, long-term evidence regarding marginal bone behavior remains limited. This study evaluated marginal bone loss after eight years of functional loading in bone-level and tissue-level implants restored according to the BOPT concept, as well as the influence of prosthesis type and arch location.
Materials And Methods:
This prospective randomized clinical study included 122 posterior implants in 71 patients after eight years of follow-up: 57 bone-level implants and 65 tissue-level implants. All implants were restored with cement-retained metal-ceramic single crowns or fixed partial dentures. Marginal bone loss was assessed using standardized periapical radiographs obtained at prosthetic loading and after eight years. Generalized estimating equation models were used to account for multiple implants within the same patient.
Results:
Tissue-level implants showed significantly lower mesial marginal bone loss than bone-level implants (0.49 ± 0.77 mm versus 0.78 ± 0.93 mm; p = 0.031). No significant differences were observed for distal or mean marginal bone loss. Fixed partial dentures were associated with greater mesial bone loss than single crowns (p = 0.025), whereas arch location did not significantly affect bone remodeling (p = 0.838).
Discussion:
Both implant systems demonstrated limited long-term marginal bone remodeling. Nevertheless, the significant difference was restricted to the mesial aspect, and the findings cannot be attributed exclusively to implant placement level or to the BOPT concept because the two implant systems differed in macrogeometry, surface characteristics and transmucosal configuration.
Conclusions:
Tissue-level implants showed lower mesial marginal bone loss after eight years, whereas distal and mean marginal bone loss did not differ significantly between systems. These findings should be interpreted considering the differences between the implant systems and the limitations of two-dimensional radiographic assessment.