Histologic wound healing in studies using different ridge preservation protocols: A review

Abstract

Background

Alveolar ridge preservation (ARP) procedures are designed to lessen dimensional changes in the alveolar ridge after tooth extraction. Wound healing after ridge preservation involves the formation of new vital bone in the former socket, and this vital bone is important in the osseointegration of dental implants.

Methods

A series of ARP studies have been performed to help clinicians better understand the wound-healing events that occur following tooth extraction and ridge preservation. Different protocols have been examined using various materials and periods of healing time prior to implant placement. The primary aim of these studies was to ascertain the relative percentage of vital bone formation, residual graft material, and connective tissue (CT)/other at the healing site using histomorphometric examination of bone core biopsies obtained during osteotomy preparation.

Results

For allografts, the use of demineralized bone alone or in combination with mineralized is associated with more vital bone formation than the use of mineralized allograft alone. For mineralized allografts, the use of cortical versus cancellous bone has only minimal impact on new bone formation. Xenografts from bovine and porcine sources appear to have similar vital bone formation. Longer healing times prior to implant placement are associated with increased vital bone formation and decreased residual graft material. The most stable component in most studies is the percentage of CT/other.

Conclusions

The percentage of vital bone and residual graft at ARP sites is dependent on the materials used and the length of healing time prior to obtaining core biopsies.

Key Points

What factors may affect the amount of new bone at the ARP site?

1. At a time point about 4 months after ARP, the type of graft material used for ARP plays a large role in new bone formation.
2. Studies focus on means and standard deviations, but patients often do not “follow the mean.” Even if a single ARP protocol is used for all patients, there is great interindividual variability in new bone formation, and there is often variability between sites within a single patient.

How long after ARP with an allograft should I wait to place an implant?

1. Longer healing times such as 4-5 months generally provide higher amounts of vital bone formation than shorter healing times like 2-3 months.
2. Differences in vital bone formation between ARP protocols tend to decrease with longer healing time.
3. FDBA that contains demineralized bone, either alone or combined with mineralized FDBA, often provides higher amounts of new bone formation than 100% mineralized allograft, especially at shorter healing periods.
4. Even a year after ARP with an allograft, residual graft material is often still present at the ARP site.