Alternatives to Autologous Bone Graft in Alveolar Cleft Reconstruction: The State of Alveolar Tissue Engineering

Comparison of three surgical models of bone tissue defects in cleft palate in rabbits

OBJECTIVE

Cleft palate is one of the most common craniofacial birth defects in the maxillofacial region. There is an urgent need in tissue regeneration research to establish animal models that faithfully mimic human diseases. Here, we compared three surgical models of bone tissue defects in cleft palate in rabbits in order to screen for the biomaterials that induced optimal bone regeneration.

DESIGN

Rabbits were used to establish the models of hard palate cleft, alveolar cleft, and alveolar process cleft. Eight weeks following surgery, bone tissue self-healing capacity was estimated by macroscopic appearance and calculating the area of defective bone tissue. The dimensions of the upper jaw in left and right sides were measured at zero and eight weeks.

RESULTS

Bone defects in three types of cleft palate models were made at the positions of the hard palate, alveoli and alveolar process. After 8 weeks, when the hard palate was partially excised, it underwent self-healing. When the hard palate was completely excised, it underwent partial self-healing. However, in the models of alveolar cleft and alveolar process cleft, there was no significant self-healing in the bone tissues. The dimensions of the upper jaw in left and right sides were no significant differences in three types of cleft palate models.

CONCLUSIONS

Bone defects in the alveolar and alveolar process clefts exhibit a diminished capability for self-healing. This study may provide valuable information for the screening of materials that induce bone regeneration.

Safety and Efficacy of Recombinant Human Bone Morphogenetic Protein-2 (rhBMP-2) in Craniofacial Surgery

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is one of the most commonly used osteogenic agents in the craniofacial skeleton. This study reviews the safety and efficacy of rhBMP-2 as applied to craniofacial reconstruction and assesses the level of scientific evidence currently available.

Recombinant Human Bone Morphogenic Protein-2 Combined With Autogenous Bone Graft for Reconstruction of Alveolar Cleft

Recombinant human bone morphogenic proteins (rhBMPs) have been introduced for reconstruction of alveolar defects. The volume of the bone formed at the cleft region may be related to rhBMP-2 dose. Greater side effects have been reported with increased doses of rhBMP-2. The aim of the present study was to assess the bone at the cleft area using low dose of rhBMP-2 combined with autogenous bone graft for reconstruction of the alveolar cleft. Patients with unilateral cleft lip and palate between the 11 to 14 years old were enrolled. After palatal expansion, autogenous graft was placed at the side of cleft in the control group (n = 6). In the BMP group, the rhBMP-2 was injected into the autogenous bone graft at the defect site (n = 5). Cone beam computed tomography (CBCT) images were taken of all patients immediately and 3 months after graft surgery to compare the density, thickness, and height of the bone graft between the 2 groups. Intermolar and interpremolar widths were also measured. The authors found less diminish of density and height of the bone graft 3 months postsurgery in patients with autogenous bone graft combined with rhBMP-2. However, significant difference in the relapse tendency of transverse dimension of the arch or thickness of the bone graft was not observed between the 2 groups. Thus, low dose rhBMP-2 combined with autogenous bone graft can be promising to reach predictable results after alveolar reconstruction in cleft lip and palate patients.

Evaluation of the Bone Regeneration Effect of Recombinant Human Bone Morphogenic Protein-2 on Subperiosteal Bone Graft in the Rat Calvarial Model

The aim of this study was to evaluate the bone regeneration effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on a subperiosteal bone graft in a rat model. A subperiosteal space was made on the rat calvarium, and anorganic bovine bone (ABB), ABB/low bone morphogenetic protein (BMP) (5 µg), and ABB/high BMP (50 µg) were grafted as subperiosteal bone grafts. The new bone formation parameters of bone volume (BV), bone mineral density (BMD), trabecular thickness (TbTh), and trabecular spacing (TbSp) were evaluated by microcomputed tomography (µ-CT), and a histomorphometric analysis was performed to evaluate the new bone formation area. The expression of osteogenic markers, such as bone sialoprotein (BSP) and osteocalcin, were evaluated by immunohistochemistry (IHC). The ABB/high BMP group showed significantly higher BV than the ABB/low BMP (p = 0.004) and control groups (p = 0.000) and higher TbTh than the control group (p = 0.000). The ABB/low BMP group showed significantly higher BV, BMD, and TbTh than the control group (p = 0.002, 0.042, and 0.000, respectively). The histomorphometry showed significantly higher bone formation in the ABB/low and high BMP groups than in the control group (p = 0.000). IHC showed a high expression of BSP and osteocalcin in the ABB/low and high BMP groups. Subperiosteal bone grafts with ABB and rhBMP-2 have not been studied. In our study, we confirmed that rhBMP-2 contributes to new bone formation in a subperiosteal bone graft with ABB.

A New Tooth Processing Apparatus Allowing to Obtain Dentin Grafts for Bone Augmentation: The Tooth Transformer

Introduction:

Human dentin matrix could be considered an excellent alternative to autologous or heterologous bone graft. Autologous tooth graft has been proposed since 1967 when the osteoinduction properties of autogenous demineralized dentin matrix were discovered.

Methods:

The preparation technique to transform autologous teeth in suitable grafting material still represents the fundamental step of the whole procedure.

Aim:

The aim of the present study was to test an innovative medical device that could obtain tooth graft materials starting from the whole tooth of the patient. 15 consecutive cases of tooth grafting procedures were performed with a mean follow up period of 18 months.

Results:

In all cases, after 6 months of healing, the defects were almost completely filled by newly formed hard tissue. The new tissue was examined after 6 months, both from a radiological point of view by CBCT scans and from a clinical observation. It showed a compactness similar to the medium-density bone. No signs of inflammations were observed. No infective complications were recorded during the post-operative healing. No graft particles or grains were visible in the regenerated bone structure that appeared homogeneous and uniform.

Discussion:

The results of the present study showed favorable bony healing in guided regenerative surgery procedures using autologous tooth graft. Future studies with long follow up period are needed in order to better evaluate the potential of demineralized dentin autografts.