Optimized 3-D CT scan protocol for longitudinal morphological estimation in craniofacial surgery

Restoration of a vertical alveolar bone defect by orthodontic relocation of a mesially impacted mandibular first molar

An impacted mandibular first molar tends to cause serious bone defects of the adjacent teeth. When choosing between the 2 typical treatment options-extraction or orthodontic relocation of the impacted tooth-the decision should be based on assessment of the prognosis. A 22-year-old man with severe mesioangulation and impaction of the mandibular first molar and a related vertical bone defect on the distal side of the second premolar was treated with extraction of the second molar and orthodontic relocation of the first molar with a retromolar miniscrew. Comprehensive orthodontic treatment involving premolar extraction was conducted. Strategic extraction of the molar and adequate orthodontic movement helped to restore the bone structure on the affected side. This case report suggests the effectiveness of restoration of bone defects by using viable periodontal tissues around the impacted tooth for the longevity of the periodontium.

Structured light scanning to evaluate three-dimensional anthropometry in HIV facial lipoatrophy

The psychological and social impact of the lipodystrophy syndrome on HIV-infected individuals may be quite considerable and adversely affect their quality of life. Currently no validated assessment tool for facial lipoatrophy is available. The main objective of this paper is to evaluate the reliability of interactive anthropometric landmark localization based on digitized 3D facial images. By comparing both computed tomography (CT) and structured light scanning we try to demonstrate that surface scanning shows a higher sensitivity in measuring facial reference points. Besides, we evaluate the reproducibility of facial 3D white-light scans. Three HIVpositive men attending our plastic surgery outpatient clinic for treatment of facial lipodystrophy were enrolled in the study. Localization of anthropometric landmarks measurements was performed on the patients. All patients underwent a facial CT and a facial white-light scanning on the same day. The inter-landmark distances measured on facial models developed from CT aided with VirSSPA 3D software and structured light scanning were compared to the real human models. We found that facial distances measured in the CT 3D reconstruction showed a mean error margin of 0.357 cm from the real distances measured on patients. On the contrary, mean error margin with the white-light scanning was of 0.096 cm. In both cases, measurements were found to be statistically significant (P<0.05). When compared to CT reconstructions, white-light surface scanning offers a more accurate landmark localization as well as reliable reconstructions of up to less than the tenth of a millimetre as average when compared to real measurements on facial human models.

Three-dimensional micro-computed tomographic imaging of alveolar bone in experimental bone loss or repair

BACKGROUND

Micro-computed tomography (micro-CT) offers significant potential for identifying mineralized structures. However, three-dimensional (3-D) micro-CT of alveolar bone has not been adapted readily for quantification. Moreover, conventional methods are not highly sensitive for analyzing bone loss or bone gain following periodontal disease or reconstructive therapy. The objective of this investigation was to develop a micro-CT methodology for quantifying tooth-supporting alveolar bone in 3-D following experimental preclinical situations of periodontitis or reconstructive therapy.

METHODS

Experimental in vivo bone loss or regeneration situations were developed to validate the micro-CT imaging techniques. Twenty mature Sprague-Dawley rats were divided into two groups: bone loss (Porphyromonas gingivalis lipopolysaccharide-mediated bone resorption) and regenerative therapy. Micro-CT and software digitized specimens were reconstructed three-dimensionally for linear and volumetric parameter assessment of alveolar bone (linear bone height, bone volume, bone volume fraction, bone mineral content, and bone mineral density). Intra- and interexaminer reproducibility and reliability were compared for methodology validation.

RESULTS

The results demonstrated high examiner reproducibility for linear and volumetric parameters with high intraclass correlation coefficient (ICC) and coefficient of variation (CV). The ICC showed that the methodology was highly reliable and reproducible (ICC >0.99; 95% confidence interval, 0.937 to 1.000; CV <1.5%), suggesting that 3-D measurements may provide better alveolar bone analysis than conventional 2-D methods.

CONCLUSIONS

The developed methods allow for highly accurate and reproducible static measurements of tooth-supporting alveolar bone following preclinical situations of bone destruction or regeneration. Future investigations should focus on using in vivo micro-CT imaging for real-time assessments of alveolar bone changes.