Influence of the implant-abutment connection on the ratio between height and thickness of tissues at the buccal zenith: a randomized controlled trial on 188 implants placed in 104 patients

Davide Farronato,Andrea Alain Orsina,Pietro Mario Pasini,Marco Farronato,Mattia Manfredini,Cristian Scognamiglio

doi:10.1186/s12903-020-1037-5

Davide Farronato, Andrea Alain Orsina + Show 4 more

Open Access

https://doi.org/10.1186/s12903-020-1037-5

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Abstract

BackgroundTo compare tissue response to two implant systems, featuring internal hexed connections with different designs.MethodsPatients enrolled in this randomized controlled trial were assigned to two groups. In Group 1, patients were treated with implants with a 5° conical internal hexed connection (Anyridge®, MegaGen, South Korea). In Group 2, patients were treated with implants with an internal hexed connection (Core®, Kristal, Italy). After implant placement and a provisionalisation period of 12 months, impressions were taken, stone casts were poured and digitised with a desktop scanner (D700®, 3Shape, Copenhagen, Denmark). In a digital environment, for each fixture, two values were collected at the buccal zenith: the height of the peri-implant mucosa (mucosal height; MH), calculated from the vestibular shoulder of the implant analogue to the upper gingival margin of the supra-implant tissue; and the width of the peri-implant mucosa (mucosal thickness; MT), calculated from the vestibular shoulder of the analogue to the external mucosa point perpendicular to the implant major axis. The mean and standard deviation for MH and MT, as well as their ratios, were calculated for each group; the sectors in which the implants were placed were also considered. Finally, correlation between MH, MT, connection type and sector was assessed by Pearson’s correlation coefficient, with significance level set at 0.05, and a confidence interval (CI) set at 95%.ResultsData deriving from 188 implants placed in 104 patients were evaluated. The mean MH values were 3.32 (± 0.12) and 2.70 (± 0.16) mm for Groups 1 and 2, respectively. The mean MT values were 4.37 (± 0.16) and 3.93 (± 0.18) mm for Groups 1 and 2, respectively. Group 1 showed higher MH and MT values and a better ratio (1.50 ± 0.88) than Group 2 (1.81 ± 1.20). The MH, MT and MH/MT ratio were significantly influenced both by sector (p = 0.015) and group (p = 0.047).ConclusionsWithin the limits of this study, the 5° connection implants supported a more extended tissue height and thickness at the buccal zenith, and a better ratio between them.Trial registrationThis study was retrospectively registered in Clinicaltrials.gov, with number NCT04160689, dated 13/11/2019.

Highlights

To compare tissue response to two implant systems, featuring internal hexed connections with different designs
As unequivocally demonstrated by the literature, after tooth extraction, a physiological mechanism of bone resorption is triggered [7, 8]; this resorption, concentrated in the first 4–6 months after extraction, is followed by soft tissues recession, and can compromise the aesthetic result of the implant therapy [9]. Such tissue contraction can be marked in the anterior aesthetic area of the maxilla, where the thin bundle bone is mainly vascularized by the periodontal ligament, and more prone to resorption [9, 10]; this can represent a challenge for the clinician, exspecially in the case of immediate implant placement [11, 12]
Regarding the correct time for implant placement, a systematic review suggests that, in post-extractive conditions, early placement might be the safest choice to avoid recessions; immediate positioning is subject to a greater variability in outcomes and a higher frequency of recessions > 1 mm of the midfacial mucosa compared to early placement [12]

Summary

Introduction

To compare tissue response to two implant systems, featuring internal hexed connections with different designs. As unequivocally demonstrated by the literature, after tooth extraction, a physiological mechanism of bone resorption is triggered [7, 8]; this resorption, concentrated in the first 4–6 months after extraction, is followed by soft tissues recession, and can compromise the aesthetic result of the implant therapy [9]. Such tissue contraction can be marked in the anterior aesthetic area of the maxilla, where the thin bundle bone is mainly vascularized by the periodontal ligament, and more prone to resorption [9, 10]; this can represent a challenge for the clinician, exspecially in the case of immediate implant placement [11, 12]

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Results

Discussion

Conclusion