Bucco-palatal implant position and its impact on soft tissue level in the maxillary esthetic zone.

AIM: The term "buccal implant position" is commonly used but lacks a precise definition and missing a reference point. Considering its major impact on peri-implantitis and esthetic failures the purpose of this study was to find a correlation between bucco-palatal implant positioning and the midfacial soft tissue level of implant crowns using newly defined Emergence-points. MATERIALS AND METHODS: Patients with unilateral single-tooth implant crowns in the region of the central or lateral maxillary incisor were included in this study. Digital intraoral scans were superimposed over a scan of the master cast or the original digital data set and analyzed in a computer planning program. In relation to the corresponding natural tooth, an ideal Emergence-point (E(IDEAL) -point) was defined from a frontal view. The distance to the real Emergence-point (E(REAL) -point) of the implant crown was correlated to apical displacement (AD) of peri-implant soft tissue. The distance of the implant shoulder (I-point) to the real Emergence-point (E(REAL) -point) of the implant crown was also correlated to the AD of peri-implant soft tissue. In cross sections, the horizontal distance between E(REAL) - and I-point represents the sagittal implant position (SIP), and the vertical distance represents the vertical implant position (VIP). RESULTS: Seventy-three patients met the inclusion criteria. AD ranged from 0 to 3.5 mm (AD = 0.87 +/- 1.01), SIP from 0.2 to 5.1 mm (AD = 2.66 +/- 1.64). Statistical analysis showed a significant inverse correlation between AD and SIP (rho = -.55, p < .001). VIP, the implant inclination, time span since implant insertion, and phenotype revealed no significant correlation to AD. CONCLUSION: The more palatal the implant was positioned, the less AD was observed. The position of the implant shoulder should preferably be planned more than 2 mm behind the ideal E-point. This E-point can be used for implant planning as it defines the ideal crown length for prospective planning.