A.B.M. Rabie

Integration of endochondral bone grafts in the presence of demineralized bone matrix

The use of endochondral bone grafts (EC) and demineralized bone matrix (DBM), which contains a potent osteoinductive matrix, may promote the repair of nonregenerative defects. The purpose of the current work is to assess qualitatively and quantitatively the effect of DBM on the healing of EC bone grafts and to compare it to the healing of EC bone grafts alone. Twenty-four defects in rabbit skulls were filled with EC bone grafts alone, DBM alone, or combined EC and DBM. Histologic and immunohistologic changes were examined in 2 weeks. The amount of new bone formation was quantified by image analysis. Healing of all the groups was characterized by the presence of a cartilage intermediate stage. In the EC bone grafts alone, healing was localized to the host bone/graft interface. In the composite group, amalgamation of the new bone, DBM, and bone graft progressed throughout the whole width and depth of the defect, uniting the graft to the recipient bed. The amount of new bone formed was significantly greater (47%) in the composite group than the EC group. In conclusion, DBM powder augments the bone-induction capacity of the recipient bed as well as the bone graft. The composite EC bone grafts and added DBM possess properties required for an effective graft material and merit further clinical evaluation.

Ultrastructural identification of cells involved in the healing of intramembranous and endochondral bones

This study was designed to identify the cells involved in the healing of autogenous intramembranous (IM) and of endochondral (EC) bone grafts. Thirty-six defects were created in the skull of 18 adult New Zealand White rabbits. Defects were filled with IM graft alone, EC graft alone, demineralized bone matrix (DBM) alone, or combined DBM-IM and DBM-EC bone. Cellular identification was carried out at 7 and 14 days by light and electron microscopy. In IM bone, preosteoblasts, osteoblasts, and osteocytes were observed with no cartilage intermediate stage, while in EC bone, chondroblasts and chondrocytes were observed. DBM implant and DBM-IM were characterized by the presence of a cartilage stage. In conclusion, IM bone healed through an osteogenic ossification route, while EC bone healed through an EC ossification route. In the presence of demineralized EC bone matrix, IM bone adopts an EC ossification route.

Dentofacial characteristics of Chinese obstructive sleep apnea patients in relation to obesity and severity

OBJECTIVE To evaluate dentofacial characteristics in relation to obesity and degree of severity of obstructive sleep apnea (OSA) in male Chinese patients and to elucidate the relationship between demographic parameters (age, body weight, height, and body mass index [BMI]) cephalometric parameters and OSA in these subjects. MATERIALS AND METHODS Lateral cephalograms of 121 Chinese male patients in natural head posture were obtained. Based on BMI value, the patients were divided into three groups. Based on apnea-hypopnea index (AHI) value, the patients were divided into a mild-to-moderate and a severe group. RESULTS The hyoid position and soft palate length were significantly different among the three obesity groups. Soft palate length was significantly longer (P < .01) in the severe OSA group than in the mild-to-moderate OSA group. Tongue base was significantly more inferiorly placed (P < .05) in the severe OSA group than in the mild-to-moderate OSA group. Craniocervical extension was significantly increased (P < .05) in the severe OSA group. Statistically significant differences were found among the three obesity groups in mandibular length, mandibular body length, maxillary length, anterior cranial base length, and overbite. The multiple stepwise linear regression analysis identified body weight, lower posterior facial height, mandibular body length, craniocervical extension, and sella-hyoid distance as the significant predictive variables for AHI. CONCLUSIONS This study revealed the existence of craniofacial and upper airway soft tissue differences in relation to obesity and severity of OSA among male Chinese OSA patients. Body weight and certain cephalometric parameters were significant predictors of OSA in Chinese male subjects.

Factors regulating endochondral ossification in the spheno-occipital synchondrosis.

OBJECTIVES To identify the temporal pattern of core-binding factor alpha1 (Cbfa1) and vascular endothelial growth factor (VEGF) expressions in the spheno-occipital synchondrosis in vitro with and without tensile stress. MATERIALS AND METHODS Sixty male BALB/c mice were randomly divided into an experimental group (with tensile stress) and a control group (without tensile stress) at each of five time points. Animals were sacrificed and the cranial base synchondroses were aseptically removed. In the experimental groups, mechanical stress was applied on the surgical explants with helical springs and incubated as organ culture for 6, 24, 48, 72, and 168 hours. In the control group, the springs were kept at zero stress. Tissue sections were subjected to immunohistochemical staining for quantitative analysis of Cbfa1 and VEGF expression. RESULTS Quantitative analysis revealed that Cbfa1 and VEGF expressions reached a peak increase at 24 and 48 hours, respectively. Compared with the control groups, both Cbfa1 and VEGF were expressed consistently higher in the experimental groups at all time points. CONCLUSION Mechanical stress applied to the spheno-occipital synchondrosis elicits Cbfa1 expression and subsequently up-regulates the expression of VEGF. Increased levels of expression of both factors could play a role in the growth of the spheno-occipital synchondrosis.

Aetiology of supernumerary teeth: a literature review.

BackgroundSupernumerary teeth are teeth, or tooth-like structures that have either erupted or remain unerupted in addition to the 20 primary and 32 permanent teeth.AimsThis paper attempts to (a) provide an overview of the proposed hypotheses and the current understanding of the aetiology of supernumerary teeth, and (b) review the published cases of supernumerary teeth occurring in families.ReviewNo studies have been able to distinguish between different aetiologies for the different locations of supernumerary teeth, while, from a developmental or molecular perspective, the proposed hypotheses may be plausible and explains the origin of different types of supernumerary teeth.ConclusionThe only clearly evident feature, based on the existing published reports, is that it is logical to state that supernumerary teeth have a genetic component in their aetiology.

Reliability of panoramic radiographs for identifying supernumerary teeth in children

OBJECTIVES. To evaluate the reliability of panoramic radiographs (PRs) for identifying supernumerary teeth (ST) and to determine whether the level of dental training of the observer influenced the identification of ST. METHODS. Seventy-five PRs were randomly selected from the patient records and 18 examiners independently rated 25 radiographs each, for specific risk factors as well as for a measure of adequacy. Subsequently, the results were paired with those of the other examiners who assessed the same set of PRs. Descriptive statistics were computed using Fishers exact test, and kappa statistics were used to assess the inter- and intra-observer reliability. RESULTS. Four hundred and fifty PRs were available for analysis. The overall sensitivity and specificity figures were 50% and 98.3%, whereas the positive and negative predictive values were 90.6% and 83.6%, respectively. The sensitivity figures for Junior House Dental Officers and Postgraduate Paediatric Dental Trainees were 39.2% and 60.8%, whereas the specificity figures were 99.4% and 95% with slight inter-examiner and moderate intra-examiner reliability. CONCLUSIONS. Panoramic radiographs are unreliable for identifying ST, and higher level of dental training is essential for identifying ST.

Diagnostic tools used to predict the prevalence of supernumerary teeth: A meta-analysis

OBJECTIVES This study sought to (i) determine the variations in prevalence figures based on the diagnostic tools employed, and (ii) provide an insight into the prevalence of supernumerary teeth. METHODS A comprehensive literature search of the prevalence reports on supernumerary teeth was conducted using two databases. Two independent observers rated these articles according to exclusion and inclusion criteria. 28 papers were included in the analysis to determine the variations in the prevalence figures in relation to the method of diagnosis, and 14 studies were included to estimate the prevalence figures for supernumerary teeth. Statistical analysis was computed using analysis of variance (ANOVA), Student Neumann-Keuls (SNK) test and multiple regression analysis. RESULTS Statistically significant differences were evident in the prevalence figures based only on a clinical examination compared with groups that also employed radiographs (p < 0.05, ANOVA, SNK). The prevalence figures for supernumerary teeth ranged from 0% to 3%. The mean prevalence value for the European white population [1.6% (±0.6)] was lower than that of the southern Chinese population [2.7% (±0.14)]. The overall prevalence of supernumerary teeth for males was significantly higher than for females [relative risk = 1.37 (1.13-1.50)]. CONCLUSIONS Clinical examination plus some types of radiograph(s) are essential for determining the prevalence of supernumerary teeth; nevertheless, it is still underestimated. Several disparities in the prevalence reports make the available data on supernumerary teeth questionable.

Effects of medicinal herb salvia miltiorrhiza on osteoblastic cells in vitro

Sufficient osteoinduction is essential for the success and effectiveness of bone grafting. It was previously found that Salvia Miltiorrhiza (SM), a commonly used Chinese herb increased osteogenesis in vivo. The aim of this study is to investigate the effects of SM on bone cells in vitro, in an attempt to get a better understanding on how SM can promote bone remodeling. MC3T3‐E1, an osteoblastic cell line, was cultured with SM for different time intervals (24, 48, and 72 h), whereas the control group consisted of cells cultured without any intervention. The mRNA expression of alkaline phosphatase (ALP), osteocalcin (OCN), osteoprotegerin (OPG), and the receptor activator of nuclear factor kappa B ligand (RANKL) were examined by real‐time polymerase chain reaction (qPCR). The expression of ALP showed an early increase at 24 h by 50% (p < 0.001) and at 48 h by 13% (p < 0.001). OCN was decreased by 22% at 24 h (p < 0.001) but increased by 50% and 88% at 48 and 72 h, respectively (p < 0.001). RANKL showed an early increase at the first two time points of 24 and 48 h by 45% (p < 0.001) and 36% (p < 0.01), respectively, while OPG was up‐regulated at the latter two time points by 10% at 48 h (p < 0.01) and 68% at 72 h (p < 0.001). Thus, OPG/RANKL was down‐regulated first, and then up‐regulated. SM enhances bone remodeling by regulating the gene expression of ALP, OCN, OPG, and RANKL. It is a potential medicinal herb to be utilized in the application that requires stimulation in bone cell activities.

A comparison between a conventional optical method and image-analysis for measuring the unimpeded eruption rate of the rat mandibular incisor

The impeded/unimpeded eruption rates of the rat incisor have been much studied. The most commonly used optical microscopic method, which has inherent weaknesses, was compared here with an image-analysis method to measure the eruption rate of the mandibular incisor. The study also evaluated the incisal edge as a reference point for the measurement of the unimpeded eruption rate, and the frequency of shortening the mandibular incisor. The image-analysis method was found to be a simple and reliable technique that could replace the optical method. There was no significant difference between the data from the two methods; their kappa coefficients were similar at the 0.99 level. It was concluded that shortening the incisor in the measurement of the unimpeded eruption rate should be done at least every 48 h, and that the incisal edge of the shortened incisor can be used as the reference point for that measurement.

RUNX2 gene status in a cleidocranial dysplasia patient without supernumerary teeth.

OBJECTIVE This study sought to perform mutational analysis of the RUNX2 gene in an 8-year-old girl with a diagnosis of cleidocranial dysplasia (CCD) without supernumerary teeth (proband) and her parents, plus in age and gender matched control subjects. METHODS Ethical approval and informed consent was obtained for this study. Blood samples were obtained and the isolated DNA was used to amplify exons 0-7 of the RUNX2 gene using specific primers, which was subsequently sequenced. RESULTS No mutations were identified in the coding regions of the RUNX2 gene. CONCLUSION The absence of supernumerary teeth in this individual with CCD demonstrates that there are variations in the phenotypes and mere absence of mutations does not imply that CCD phenotype is not governed by RUNX2 gene as only two-thirds of the individuals exhibiting a CCD phenotype would reveal a RUNX2 mutation; therefore, the influence of copy number variations including large insertions, intragenic deletions, duplications, and inversions of genes cannot be excluded completely.