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Soft Tissue Volume Augmentation at Single Implant Sites Applying Collagen Matrices or Connective Tissue Grafts:
Franz J Strauss1,2, Margherita G Liguori3, Thomas J W Gasser4
1Discipline of Periodontics, The University of Sydney, School of Dentistry, Sydney, New South Wales, Australia.
Aim:
To compare up to 10 years clinical, profilometric and patient-reported outcomes of implant sites previously augmented using a volume-stable collagen matrix (VCMX) or connective tissue graft (SCTG) in the aesthetic zone.
Methods:
The original non-inferiority randomized controlled trial (RCT) enrolled 20 patients who received soft tissue volume augmentation with VCMX or SCTG at single implant sites. Clinical assessments and standardized measurements were performed at baseline after crown insertion and at 6 months, 1, 3, 5, 7.5, and 10 years. The primary outcome was mucosal thickness. Secondary outcomes included marginal bone levels (MBL), probing depth (PD), bleeding on probing (BOP), plaque control record, Pink Aesthetic Score (PES), OHIP-14 and buccal profilometric changes. Group comparisons were performed using mixed-effects and generalized estimating equation (GEE) models, which account for within-patient correlations due to repeated measurements and allow inclusion of all available data without requiring imputation for missing observations.
Results:
Of the 20 originally enrolled patients, 10 (5 in the SCTG group and 5 in the VCMX group) were available for re-examination at 10 years. The adjusted between-group difference in mucosal thickness was -0.02 mm (95% CI -0.99 to 0.96). As the lower bound of the confidence interval remained above the prespecified non-inferiority margin of -1 mm, non-inferiority of VCMX was shown. Buccal contour changes were comparable during the early follow-up, while a trend toward a greater long-term contour decrease was observed in group VCMX (-0.31 mm [95% CI, -0.65 to 0.03]; p = 0.07). Mean PES values were 10.6 in the SCTG group and 9.6 in the VCMX group, with no significant between-group differences (p = 0.45). Both groups revealed high levels of oral health-related quality of life, with low median OHIP-14 scores (SCTG, 0.0; VCMX, 1.0; p = 0.26).
Conclusion:
These preliminary long-term findings showed no clinically relevant differences between SCTG and VCMX in terms of clinical, profilometric and patient-reported outcomes. While SCTG remains the reference standard, VCMX represents a less invasive alternative but with a slight tendency toward greater long-term contour reduction.
Clinical Significance:
Volume-stable collagen matrices serve as a viable alternative to autogenous connective tissue grafts for peri-implant soft tissue volume augmentation, particularly in patients seeking a reduced morbidity, without compromising long-term clinical or aesthetic outcomes.
Trial Registration:
German Clinical Trials Register: DRKS00017484.
