Influence of apico‐coronal positioning of tissue‐level implants on marginal bone stability during supracrestal tissue height establishment: A multi‐center prospective study

Abstract

Introduction Supracrestal tissue height establishment is a crucial factor influencing peri‐implant marginal bone modifications prior to prosthesis delivery. If mucosal thickness is insufficient, peri‐implant marginal bone resorption occurs to allow appropriate supracrestal tissue height formation. This study evaluates if marginal bone resorption occurring around tissue‐level implants before prosthetic loading could be compensated by adapting apico‐coronal positioning to mucosal thickness. Methods Patients requiring placement of one single implant in the posterior mandible were treated with tissue‐level implants with a 3‐mm high transmucosal machined component and moderately rough implant body. Based upon vertical mucosal thickness measured after buccal flap reflection, implants were placed with the treated part: (group 1) 2 mm below crestal level in presence of thin mucosa (<2.5 mm); (group 2) 1 mm below the crestal level in presence of medium mucosa (2.5–3.5 mm); (group 3) at equicrestal level in presence of thick mucosa (>3.5 mm). Results Forty‐nine implants, placed in 49 patients were included in final analysis (group 1: 18 implants; group 2: 16 implants; group 3: 15 implants). Mean marginal bone resorption after 5 months of healing was 0.66 ± 0.49 mm, 0.32 ± 0.41 mm, and 0.22 ± 0.52 mm in groups 1, 2, and 3, respectively. Inter‐group analysis highlighted significant differences between the three groups after ANOVA test (p = 0.025). However, adaptation of apico‐coronal implant positioning in relation to mucosal thickness, allowed to avoid early exposure of the treated surface in 100%, 93.7%, and 53.3% of the implants in groups 1, 2, and 3, respectively. Conclusion During supracrestal tissue height formation, tissue‐level implants inserted adapting apico‐coronal positioning in relation to mucosal thickness exhibited greater marginal bone resorption at sites with thin mucosa than at sites with medium or thick mucosa. However, anticipating supracrestal tissue height establishment by adapting apico‐coronal implant positioning in relation to mucosal thickness may effectively prevent unwanted exposure of treated implant surface.

Marginal bone changes around platform‐switched conical connection implants placed 1 or 2 mm subcrestally: A multicenter crossover randomized controlled trial

“…At T2, 6 Control group implants exhibited PBL below the implant platform (11.8% of Control group implants), whereas no early implant surface exposure was recorded in Test group. This outcome, consistent with previous studies, 8,35,53,69 suggests that 2 mm subcrestal positioning could be beneficial in terms of preventing further MBL 24 and future onset of peri-implantitis. 27,28 Moreover, Test implants resulted in a significant more subcrestal position at T2, when compared with Control implants (1.44 ± 0.50 and 0.60 ± 0.43 mm, respectively).…”

“…At T1, after 5 months of unsubmerged healing, Test implants lost significantly more bone than Control implants (0.44 ± 0.30 and 0.28 ± 0.32 mm; p = 0.005). This finding is consistent with numerous clinical studies showing greater bone remodeling related to supracrestal tissue height establishment when an implant is placed in a deeper subcrestal position 8,35,53–55 …”

“…Implant site preparation was performed by experienced clinicians after a calibration session held prior to the study. Most clinical variables potentially influencing EMBL were controlled in the study protocol (site‐related factors [crestal bone width ≥6 mm 1–3 ; mucosal thickness ≥2.5 mm 8,45 ; keratinized mucosal band width ≥4 mm 46,47 ], surgical‐related factors [bone overheating 48 and excessive implant IT 5,49 ] and prosthetic factors [platform‐switched conical connection 19,50 ; 3 mm high prosthetic abutment 14–16 ; one abutment‐one time protocol 12,13 ; and screwed prosthetic retention 51,52 ]).…”

“…During the first year of function, peri-implant crestal bone undergoes a remodeling process with multifactorial etiology and variable entity. This noninfective process, namely early marginal bone loss (EMBL), is affected by various surgical and prosthetic factors including insufficient bone crest width and/or implant malpositioning, [1][2][3] excessive surgical trauma, 4,5 supracrestal tissue height adhesion, [6][7][8] microleakage and bacterial accumulation at the implant-abutment microgap, [9][10][11] repeated abutment disconnection/reconnections, 12,13 prosthetic abutment height, [14][15][16][17][18] implant-abutment connection mechanical stability 19 and structural bone adaptation to functional loading. 20 Traditionally, EMBL up to 1.5-2 mm followed by a maximum of 0.2 mm annually thereafter, was commonly observed and considered a defining criterion of implant success.…”

Impact of peri‐implant soft tissue characteristics on health and esthetics

“…According to the findings of a study aimed at assessing the effect of STH on the development and resolution of experimental peri‐implant mucositis, mucosal tunnel ≥3 mm was associated with a less favorable pattern of disease resolution compared to sites presenting a mucosal tunnel of ≤1 mm 63 . Therefore, it is important to carefully plan and appropriately execute the surgical intervention to place the implant fixture at the ideal depth, balancing anatomical, implant and prosthetic factors 64 …”