The Influence of Bone Allograft Particle Sizes on the Quantity and Quality of New Bone Formation in Grafted Extraction Sockets and Edentulous Ridges

A Randomized Trial to Evaluate the Effect of Allograft Bone Particle Size on Histomorphometric and Clinical Outcomes Following Ridge Preservation/Augmentation Procedures

This study will evaluate the effect of allograft bone particle size on the bone quantity and quality following socket grafting and lateral ridge augmentation in preparation for endosseous implant placement.

Pre (baseline)- and post-grafting (3 months for sockets and 6 months for edentulous ridges) clinical as well as 2- and 3-dimensional radiographic measurements will be used to evaluate the differences between sites grafted with small vs. large particle sized bone allografts.

Histological analysis will be performed at time of surgical re-entry of grafted sites to place the dental implants, and assessed for differences in new bone formation between the 2 types of grafts.

This study is a prospective, two-arm, randomized trial that will evaluate and compare the bone healing following ridge preservation of extraction sockets (RP, Arms 1 and 2) or lateral ridge augmentation of edentulous sites (RA, Arms 3 and 4) using either small particle (SP) or large particle (LP) mineralized cortico-cancellous bone allografts in a total of 48 patients (12 in each arm).

Study approval was obtained from the university's institutional review board. Qualifying participants and defects are randomized following a computerized permutation block to receive either LP or SP allografts on day of surgery. In the RP arms, tooth extraction is performed with a flapless minimally invasive technique, followed by socket grafting with a randomized graft covered with a collagen dressing and sutures. In the RA arms, lateral ridge augmentation is conducted utilizing a randomized bone graft covered by a collagen membrane fixated with tacks.

The mineralized cortico-cancellous bone allografts utilized in this study were all obtained from the same donor, lot and tissue bank to account for variation in age, race, gender and related healing potential of different graft sources.

In the RP arm, bone core biopsies will be harvested at time of implant placement 3 months following socket grafting, whereas similar biopsies will be obtained at 6 months following lateral ridge augmentation in the RA group. These 2x2x6 mm bone cores will then undergo histological and histomorphometrical analyses to determine qualitative and quantitative healing differences between LP and SP in all study arms.

Clinical measurements are gathered at 2 time points (grating and implant placement) at all defects and will be compared for differences.

Cone beam computed tomography (CBCT) initial scans are conducted immediately following socket grafting (RP arms) and prior to ridge augmentation (RA arms) and second scans obtained prior to implant placement (all RP and RA arms). Virtual implant planning software (coDiagnostiX) will be utilized to assess and compare the 2- and 3-dimensional changes for all defects.

Inclusion Criteria:

• English speaking
• At least 18 years old
• Must be a patient of the UAB Dental School
• Able to read and understand informed consent document
• Need for implants to replace missing tooth or teeth in at least one quadrant of the mouth.
• Hopeless tooth or teeth planned to be replaced with dental implant(s)_socket with residual 4 walls following minimally invasive tooth extraction (a dehiscence of <3mm may be included) or insufficient alveolar ridge width for endosseous implant placement defined as 5mm or less as determined by bone sounding and cone beam computed tomography (CBCT) scan.
• Patient and/or guardian is willing and able to comply with the preoperative and postoperative diagnostic and clinical evaluations required.

Exclusion Criteria:

• Non-English speaking
• Less than 18 years old
• Smokers/tobacco users (>10 cigarettes/day)
• Patients with systemic pathologies or conditions contraindicating oral surgical procedures or adversely affecting wound healing
• Patients with significant medical conditions or habits expected to interfere with bony healing.
• Patient is a poor compliance risk (i.e., poor oral hygiene, history of alcohol or drug abuse)
• Bone dehiscence of >4mm following tooth extraction or Vertical loss of bone at edentulous ridge