Dental implants are commonly prescribed as a treatment modality for the replacement of missing teeth, recognized for their high survival rates and satisfactory clinical performance. However, complications may occur. Patients’ expectations may also have increased, adding to the challenge of meeting anticipated outcomes. The International Team for Implantology’s SAC (straightforward, advanced, complex) criteria (Dawson et al. 2022) were developed as a vital communication tool to educate patients as to their individual risk factors.

Within the available literature, the significance of the association between the peri-implant hard and soft tissue dimensions at the time of implant placement related to the occurrence of biological and esthetic complications is as yet unknown.

Biological, mechanical, and technical factors may influence hard and soft tissue dimensions. Peri-implant mucositis with progression to peri-implantitis (characterized by inflammation in the peri-implant mucosa and the subsequent progressive loss of bone (Berglund et al. 2018)) is the most apparent biological cause. Peri-implantitis is challenging to treat and can ultimately result in the loss of the implant (Derks et al. 2016). Peri-implant bone loss may also result in undesirable esthetic changes related to the marginal position of the peri-implant soft tissues (Chackartchi et al. 2019), with mechanical complications (such as loosening and fracture of the retaining components (Sailer et al. 2022)) potentially contributing to vertical bone loss related to inflammation if left unmanaged. Technical complications such as implant malposition (Chen et al. 2023) may influence the final position of the gingival margin because the peri-implant supra-crestal soft tissue (averaging 3.4 mm in an animal model (Askar et al. 2020)) follows the underlying bony contours.

After tooth extraction, hard tissue dimensional changes occur with one third of the ridge width lost within the first 3 months and 50% at 12 months (Schropp et al. 2003). Once healed, cortical bone forms the outer layer of the buccal bone wall and has a blood supply from both the periosteum and cancellous bone (Roush et al. 1989). Surgical interventions interrupt the blood supply and may cause a degree of avascular necrosis (Mankin 1992), leading to bony remodeling with a greater emphasis towards the buccal aspect (Monje 2019). Buccal bone wall thickness (BBT) around an implant has long been identified as a factor that may influence the development of peri-implant disease and stability of the peri-implant mucosa (Farroneto et al. 2020), as vertical bone loss (VBL) may result in mucosal recession (Schwarz et al. 2016). An implant fully integrated into bone around its micro-rough surface may be more likely to withstand the onset of peri-implant disease when compared to an implant with a bony dehiscence as bacterial contamination of the micro rough surface may lead to further bone loss (Roux & Orcel 2000) and, potentially, to the loss of the implant (Spray et al. 2000). Not all reports have shown this correlation, with one clinical study delivering results that rejected the cause-and-effect status afforded to complications associated with a bony dehiscence (Temmerman et al. 2015). The report cited no negative impact on clinical and radiographic outcomes at three years of follow-up when considering alveolar bone dimensions. Therefore, understanding the role BBT plays in tissue stability and onset of disease appears to be of clinical significance.

The integrity of the supra-crestal soft tissue is of equal importance to the peri-implant bone health, so investigating the role of soft tissue augmentation (STA) in preventing mucosal complications is paramount. STA allows clinicians to modify the phenotype of the peri-implant mucosa with several potential benefits (Avila-Ortiz et al. 2020; Zuchelli et l. 2020). STA provides the opportunity to augment the volume of soft tissue around implants or to reposition the gingival margin around both teeth and implants, with both interventions providing the possibility to improve pink esthetic scores (Furhauser et al. 2005) (PES). Increasing the thickness of peri-implant tissue may camouflage the negative esthetic impact of a darker abutment material on the overlying mucosa (Jung et al. 2017). Studies have suggested that both keratinized mucosal width (KMW) and mucosal thickness (MT) have protective effects on the underlying marginal bone levels (MBL) and stability of the soft tissue margin (Bhat et al. 2015). Limited or absent keratinized mucosa may present challenges to patients’ oral hygiene related to discomfort on brushing. STA to increase the width of keratinized mucosa has been shown to improve patient-reported outcomes (PROMS) when performing oral hygiene measures (Perussolo et al. 2018). By association, any improvement in plaque control around a dental implant may ultimately reduce the risk of peri-implant mucositis and its potential progression to peri-implantitis.

Group 1 was tasked with reporting on the available literature relating to the surgical techniques and biological parameters of two themes.

Firstly, to investigate the influence of BBT and the critical overall dimensions of alveolar bone on hard and soft tissue stability around an implant at the time of placement, therefore also to explore the need for simultaneous bone augmentation procedures according to the residual BBT.

Secondly, to investigate the medium- and long-term effects of STA at implant sites and to explore the effect of different approaches including clinical, patient reported and health-related parameters.

The overarching ITI Consensus Report for surgical techniques was based on the two systematic reviews, which were prepared in advance. Subsequent expert discussions took place to deliver a Consensus Report and Statements that included clinical recommendations, recommendations for future research and reflections on patient perspectives.