Abstract
This study was conducted to comparatively examine spontaneous healing versus ridge augmentation, in surgically-created dehiscence defects, associated with chronic pathology in dogs. Mandibular second, third and fourth premolars (P2, P3 and P4) were hemi-sectioned, and a dehiscence defect was created at the mesial root, while a groove was made on the buccal area from the top of the teeth to the bottom of the defect, exposing the dental pulp. The mesial roots of P2, P3 and P4 were extracted 1 month after the induction of the dehiscence defect with chronic pathology. Three teeth were randomly allocated to these experimental groups: (i) spontaneous healing without any bone graft (Control group: C); (ii) ridge augmentation with β-tricalcium phosphate (β-TCP) granules (Test 1 group: T1); and (iii) ridge augmentation with 60% hydroxyapatite (HA) and 40% β-TCP microspheres (Test 2 group: T2). Postmortem histopathologic examination showed significant between-group differences in C and T1 and C and T2 in bone volume/tissue volume in qualitative micro-computed tomography (CT) analysis, as well as significant intergroup differences in the coronal area at 4 and 12 weeks. The composition of connective tissue and mineralized bone in C and T1 were higher than in T2 at 4 weeks of healing, whereas the composition of mineralized bone was higher in T2 than in T1 at 12 weeks of healing. Biphasic calcium phosphate, composed of 60% HA and 40% β-TCP microsphere (i) potentially prevented marked osteoclastic resorption and (ii) promoted ridge preservation in the extraction socket with the dehiscence defect and chronic pathology.
Highlights
Appropriate treatment for the extraction site before implant placement is dependent upon understanding the biological healing processes involved in the extraction socket
Soft-tissue healing was complete at 1-month post-induction of the dehiscence defect with chronic pathology (Figure 3a)
When the tooth with chronic pathology was extracted, a marked buccal bone defect was detected by using a probe compared to the lingual bone plate
Summary
Appropriate treatment for the extraction site before implant placement is dependent upon understanding the biological healing processes involved in the extraction socket. Several studies have reported that alveolar contractions occur horizontally and vertically after tooth extraction [1,2,3]. Most of these studies have investigated dimensional changes after tooth extraction in the intact extraction socket wall and/or with periodontally healthy status. Ridge preservation can significantly reduce ridge contraction, as compared to sites that have spontaneously healed. Ridge augmentation to reduce ridge contraction can be carried out when the extraction socket wall is damaged [6,7]. The effect of the flapless ridge preservation/augmentation and/or extraction socket healing at the infected site could not be ascertained in the model used in the abovementioned studies
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