Advisory Committee Chair
Advisory Committee Members
Date of Award
Degree Name by School
Master of Science in Dentistry (MScD) School of Dentistry
Guided bone regeneration (GBR) can be used to augment deficient alveolar ridges in preparation for dental implant placement. Mucogingival deformities can result from the periosteal releasing incision during GBR. This can be addressed by additional soft tissue augmentation procedures to increase the width of keratinized tissue and vertical soft tissue thickness, both of which have demonstrated clinical benefits around implants. The drawbacks of soft tissue augmentation following ridge augmentation include an additional procedure, increased patient morbidity, and less patient acceptance of treatment. In general, soft tissue augmentation can be performed at various time points throughout treatment, but literature on soft tissue augmentation at the time of GBR is lacking.The present study combined hard and soft tissue augmentation into one procedure and compared the clinical outcomes using autogenous connective tissue grafts (CTG) or allogeneic acellular dermal matrix (ADM). A total of 24 patients completed the study. The patients were randomized into the CTG group, ADM group, or the control group. The patients underwent 2 surgical procedures. A cone beam computed tomography (CBCT) scan and intraoral scan were obtained prior to both surgical procedures. Surgery 1 involved GBR and soft tissue grafting, if applicable. After a healing period of at least 6 months, surgery 2 involved a soft tissue biopsy from the augmented site and implant placement. Outcome measures were obtained clinically at the time of the surgical procedures and digitally in software after the completion of both surgical procedures. Width of keratinized tissue was assessed clinically, while soft tissue (horizontal) thickness 4 mm from the alveolar crest and soft tissue (vertical) thickness at the incision line were assessed both clinically and digitally. The soft tissue samples were analyzed histologically. Means and standard deviations of the clinical and digital measurements were calculated. The augmented ridges for some patients included 1-3 tooth sites, and all sites were included for statistical analysis. In these patients, because the outcome measures were nested within the same individual the assumption of independence could not be made, and a Type 3 Generalized Estimating Equation (GEE) analysis was utilized to compare the differences across the means of 3 groups. When this analysis showed a significant effect, Tukey’s Honest Significant Difference (HSD) test was used to compare the means between 2 groups. Clinically, only the change at the crest demonstrated a significant difference (CTG: 1.9091 mm; ADM: 1.6000 mm; control: 0.3333 mm) (P = 0.0168). There were significant differences between CTG and control (P = 0.0008) and between ADM and control (P = 0.0040), but no significant differences were found between CTG and ADM. Digitally, only the change at the crest measured from the superimpositions of the CBCT and intraoral scans had statistical significance (CTG: 1.6400 mm; ADM: 0.6158 mm; control: -0.1880 mm) (P = 0.0133). There were significant differences between CTG and control (P < 0.0001). Histologically, both CTG and ADM appeared to be well incorporated in the native tissues as a dense collagen matrix. The idea behind simultaneous soft tissue and hard tissue augmentation is to decrease patient morbidity by reducing the number of surgical visits. However, in some patients, a second procedure may still be needed to deepen the vestibule or increase the width of keratinized tissue. Therefore, this simultaneous protocol may not have eliminated the need for a second procedure. In conclusion, within the limits of this study, both gains in alveolar ridge width and vertical soft tissue thickness can be achieved in one procedure. However, the need for a second procedure may not have been prevented. Therefore, if this protocol is utilized, ADM should be used at the time of GBR, so that if a second procedure is needed, a palatal graft can be used predictably to increase the width of keratinized tissue. Thus, there is still the possibility of only one surgical procedure, but if a second surgery is necessary, the patient will only have to undergo a palatal graft once.
Liu, Kenneth, "A randomized controlled trial to compare the histomorphometric and clinical outcomes of soft tissue augmentation at the time of lateral ridge augmentation procedures" (2021). All ETDs from UAB. 845.