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

Abstract

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 (ρ = -.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.

Keywords: buccal malposition; bucco-palatal implant position; dental implant; maxillary esthetic zone; sagittal implant position; soft tissue level.