DOI: 10.25549/usctheses-c40-386602
title: The effect of vertical and horizontal level discrepancy of teeth and adjacent dental implants on periodontal and peri-implant bone level changes: a retrospective radiographic analysis

description: Introduction: The purpose of the present study was to investigate the effect of vertical and horizontal discrepancies between implants and adjacent teeth and alterations in crestal bone. The hypothesis tested was that “vertical level discrepancy (VLD) of implants and adjacent teeth is associated with marginal bone loss (MBL), the effects of which increases as the horizontal position of between implants to teeth decreases or the vertical distance increases”. Therefore, the aim of the present retrospective study is to evaluate the longitudinal alterations in radiographic proximal marginal bone levels on implants and adjacent teeth in relation horizontal and vertical distances between units. ❧ Materials & methods: Radiographic records of patients (n=100) who had received single or multiple adjacent dental implants adjacent to a natural tooth, at three treatment centers were examined. Inclusion criteria consisted of: 1) single or multiple adjacent dental implants restored with splinted or non-splinted restorations, 2) availability of diagnostic quality radiographs at time of implant installation, prosthesis installation and at least one year post implant loading. Parameters of interest were as follows: vertical discrepancy between the platform of the adjacent implants and teeth (VD-TCEJ, horizontal distance between the implants and teeth, distance between the implant platform and bone level at the first implant bone contact at the mesial and distal surfaces of the implants designated as bone level, bone level of teeth measured from the CEJ. Pearson correlation coefficient was calculated to determine the relationship between implant-tooth proximity measurements, marginal bone loss and crestal bone loss. In order to determine the effect of implant position on marginal bone level, the data were categorized into different horizontal and vertical subgroups. Two-tailed independent student t test with alpha value of .05 was used to evaluate the difference in mean marginal bone level between the compared groups. The results were presented as mean values ± standard deviations. ❧ Results: 100 patients with the mean age of 62 ± 11.2 years having 233 implants and 102 teeth with the mean follow up period of 55.3 ± 27.6 months fulfilled the inclusion criteria. The mean VD-TCEJ was 3.82 ± 1.88 mm and the mean horizontal distance between the implants was 3.02 ± 1.59 mm. The mean vertical discrepancy between implant platform and adjacent bone crest was 1.57 ± 1.88 mm. A significant negative correlation (P= 0.021, R² =−0.199) was found between implant diameter and crestal bone loss on teeth between placement to prosthesis delivery. Same was observed, between placement and final follow up (P=0.024, R² = −0.189). A significant difference in marginal bone loss on the implants and teeth between placement and final follow up was observed among implants &lt;5 mm diameter versus those ≥ 5mm (P = 0.001), with the later experiencing greater MBL.  When the vertical discrepancy between implant platform and CEJ of the adjacent tooth was more than 3mm, there was a significant positive correlation (P= 0.029) between implant marginal bone loss (from placement and follow up) and VD-TCEJ. Additionally, a highly significant negative correlation (P=0.003) was found between tooth crestal bone loss between placement and follow up and vertical discrepancy between the implant platform and bone crest. Finally, Astra Tech implants and Nobel Biocare implants experienced significantly less marginal bone loss than 3i implants. ❧ Conclusion: In the presence of implant diameter ≥ 5mm, greater marginal bone loss occurs on the implant and adjacent tooth. In the presence of a vertical discrepancy of &gt;3mm between implant platform and tooth CEJ, greater implant marginal bone loss occurs. When the vertical discrepancy between implant platform and bone crest &gt;1mm, greater tooth crestal bone loss occurs.