Evaluation of bone tissue healing following alveolar ridge preservation with deproteinized bovine bone mineral covered with xenogenic collagen matrix: A clinical and histological study in humans

The objective of the study was to histologically evaluate the new bone formation (Nevins et al. 2011; Nevins et al. 2014) and tissues dimensional changes (Nevins et al. 2006; Laurito et al. 2016) following two different healing protocols (16-weeks and 32-weeks) using deproteinized bovine bone mineral (DBBM) covered with a collagen matrix (CM) for alveolar ridge preservation in the aesthetic area. Sixteen patients requiring the extraction of a single tooth in the frontal area were recruited. Following surgical tooth extraction, in each patient the alveolus was filled with DBBM with 10% collagen (Bio-Oss® Collagen; Geistlich Pharma). A xenogenic reabsorbable CM (Mucograft®, Geistlich Pharma) was subsequently adapted to cover the DBBM. The vertical distance from the center of the buccal and palatal/lingual alveolar crest (AC) and the cemento-enamel junction (CEJ) of the adjacent teeth and the buccal-palatal/lingual alveolar width and thickness was measured. Then each patient was randomized in short-term (16 weeks) or long-term(32 weeks) healing protocol. A Student t-test was performed for the analysis of clinical and histological changes between groups. p<0.05 was set as statistically significant. No significant difference were found in the thickness of the buccal plate (short 1.09±0.26mm vs long term 1.15±0.31mm), in the CEJ-AC buccal distance change (short 2.38±0.22mm vs long term 2.49±0.26mm), in the palatal/lingual CEJ-AC distance (short 2.41±0.31mm vs long term 2.37±0.24mm) and in the buccolingual alveolar thickness between groups(P=0.12). However, the 32-week protocol resulted in a better new bone formation and fewer tissue dimensional changes (P=0.01) compared to the 16-week. The 16-week group presented a vital bone 2 percentage of 35.58% compared to 47.76% of the 32-week. Regarding the percentage of residual graft, there was no significant difference between groups (short-term=34.23%, long-term=25.43%). This study indicates significantly greater new vital bone formation by a xenograft protocol for the alveolar socket preservation with DBBM plus CM at 32-weeks compared to 16-weeks before dental implant placement.