Pontic site development for fixed dental prostheses with and without soft tissue grafting: 1-year results of a cohort study
Authors: Strauss Franz J. , Huber Brandon J. , Valdés Ana , Jung Ronald E. , Mühlemann Sven , Thoma Daniel S. 
Published: July 2022

Abstract

Aim
To describe and compare the pontic site development for fixed-dental prostheses (FDPs) with and without soft tissue grafting up to one-year post insertion of FDPs.

Materials and methods
A convenience sample of 24 patients participating in an ongoing RCT was provided with three-unit tooth-borne FDPs. Six patients received a subepithelial connective tissue graft (SCTG) at the pontic site, whereas 18 patients were treated without any soft tissue graft (CONTROL). Digital impressions were taken prior to tooth preparation, after tooth preparation, after insertion of the final FDP, and at the 1 year of follow-up. The obtained stereolithography files (STL) were superimposed and profilometric as well as linear changes of the soft tissue profile were assessed at the pontic regions. Profilometric outcomes included changes of the ridge contour, the alveolar ridge width, and the crown height of the pontic. Further outcomes assessed included: the papilla index, the pink esthetic score (PES), probing depth (PD), bleeding on probing (BOP), and plaque control record (PCR). Descriptive and nonparametric statistics were applied for all outcome measures.

Results
The median profilometric contour between tooth preparation and 1 year after the insertion of the final FDP decreased by − 0.25 mm [Q1, Q3: − 0.36, 0.14] in the CONTROL group and increased by 0.61 mm [Q1, Q3: − 0.18, 1.06] in the SCTG group (intergroup p = 0.038). The alveolar ridge width between prior to tooth preparation and the one-year follow-up amounted to − 0.12 mm [Q1, Q3: − 0.74, 0.70] (= loss) in the CONTROL group and to 2.23 mm [Q1, Q3: 0.62, 3.86] (= gain) in the SCTG group (intergroup p = 0.032). At one year, the median crown height of the pontic tended to decrease by − 1.24 mm [Q1, Q3: − 2.05, − 1.05] in the SCTG group (intragroup p = 0.094) and by − 0.22 mm [Q1, Q3: − 0.58, 0.66] in the CONTROL group (intragroup p = 0.831), with significant differences between the groups (intergroup p = 0.022). The papilla index between prior to tooth preparation and one year of follow-up improved significantly in both groups (p < 0.05). Between FDP delivery and one year of follow-up, the PES values decreased significantly in the CONTROL group (intragroup p = 0.007), while in the SCTG group the change was not significant (intragroup p = 0.875). Clinical parameters (PD, BOP, and PCR) remained stable over time and did not differ between the groups at any time point (intergroup p > 0.05).

Conclusion
Within the limitations of the present study, soft tissue grafting tends to limit contour changes at pontic sites, thus maintaining the esthetic outcomes over time. The lack of soft tissue grafting results in stable clinical outcomes; however, it may lead to a decrease in aesthetic outcomes over time.

Clinical relevance
Autogenous soft tissue grafting seems to be a valid therapeutic option for the development of the pontic site to restore ridge defects prior to the delivery of fixed dental prostheses and to limit dimensional changes over time.