Dentistry has searched for an ideal material to place in osseous defects for many years. Endogenous bone replacement has been the golden standard but involves additional surgery and may be available in limited quantities. Also, the exogenous bone replacement poses a risk of viral or bacterial transmission and the human body may even reject them. Therefore, before new biomaterials are approved for medical use, mutagenesis systems to exclude cytotoxic, mutagenic or carcinogenic properties are applied worldwide. The present preliminary study was carried out in five male New Zealand white rabbits (Oryctolagus cuniculus). Porous form of synthetic hydroxyapatite granules (500 mg), manufactured by School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Penang, was implanted in the femur of the rabbits. Blood samples were collected prior to implantation and one week after implantation. The blood was cultured in vitro and the cell division was arrested at metaphase using colcemid. This was followed by the hypotonic treatment and fixation. Then, the chromosomes were prepared and stained for analysis. The modal chromosome number of rabbit (Oryctolagus cuniculus) was found to be 2n=44. The mean mitotic index values prior to and after implantation were 3.30 ± 0.66 and 3.24 ± 0.27 per cent respectively. No gross chromosome aberrations, both numerical and structural were noticed either prior to or after implantation of the biomaterial. These findings indicate that the test substance, synthetic hydroxyapatite granules does not produce gross chromosome aberrations under the present test conditions in rabbits.
We present an algorithm to reduce the number of slices from 2D contour cross sections. The main aim of the algorithm is to filter less significant slices while preserving an acceptable level of output quality and keeping the computational cost to reconstruct surface(s) at a minimal level. This research is motivated mainly by two factors; first 2D cross sections data is often huge in size and high in precisions – the computational cost to reconstruct surface(s) from them is closely related to the size and complexity of this data. Second, we can trades visual fidelity with speed of computations if we can remove visually insignificant data from the original dataset which may contains redundant information. In our algorithm we use the number of contour points on a pair of slices to calculate the distance between them. Selection to retain/reject a slice is based on the value of distance compared against a threshold value. Optimal threshold value is derived to produce set of slices that collectively represent the feature of the dataset. We tested our algorithm over six different set of data, varying in complexities and sizes. The results show slice reduction rate depends on the complexity of the dataset, where highest reduction percentage is achieved for objects with lots of constant local variations. Our derived optimal thresholds seem to be able to produce the right set of slices with the potential of creating surface(s) that traded off the accuracy and speed requirements.
The purpose of this study was to determine the dimensional accuracy of the skull models produced by Rapid prototyping technology using stereolithography apparatus. Computed tomography images were captured from four dry normal adult human skulls. The resultant 2-D images were stored in Digital Imaging and Communications in Medicine (DICOM) format. The segmentation of the images was prepared in MIMICS software. The slice files were then exported to a stereolithography apparatus (SLA) to produce the replica of each skull. Eight linear measurements were repeatedly made between identified landmarks on each of the original skull and its replica model using an electronic digital calliper. Each of the linear measurements was repeated 5 times and the average was taken to determine the absolute difference and percent difference between the original skull and its replica model. The overall absolute difference between the four human adult skulls and its replica models was 0.23 mm with a standard deviation of 1.37 mm. The percent difference was 0.08% with a standard deviation of 1.25%. The degree of error established by this system seems affordable in clinical applications when these models are used in the field of dental surgery for surgical treatment planning.
The prevalence of cleft lip and palate in human is 1 in 500 live births worldwide. Non·syndromic clefts are a complex trait with both genetic and environmental etiology. The aim ofthe study was to assess the association between maternal exposure to second-hand smoke during pregnancy and ruk of having cleft child. Unmatched case-control study was carried out among Malays in Kelantan.
1 Case and control subjects were denned as mothers of cleft children and mothers of normal children respectively. The cleft children were recruited from the Combined Cleft Clinic at Kota Bharu Dental Clinic. Normal chiMren were selected at Orthodontic Clinic, Kota Bharu. A total of 184 cases and controb with age range from 17 to 50 years were interviewed using the standard craniofacial
registration form. Multiple Logistic Regression modeling was used to estimate adjusted odds ratio of factors associated with non-syndromic oral cleft. Signijicant factors include history of miscarriage (OR: 3.40; 95% C1:1.05, 11 .08) p=0.042; duration of exposure to second-hand smoke for 15-30 minutes (OR: 2.41; 95% C1:1.42, 4.09) p 30 minutes (OR: 5.16; 95% C1:Z.87, 9.28) p
A review of incident oral and maxillofacial biopsies in Kelantan from January 1994 to December 1998 was carried out to evaluate the scope of pathological lesions managed by the two main oral and maxillofacial units in this state. A total of 357 biopsy reports from incident cases of pathological lesions were reviewed. The biopsies were mainly from intra-oral sites (n=326, 91.3%). Females had more frequent oro-facial lesions compared with males (male:female ratio is 0.8:1). The Bumiputera ethnic group had the most number of biopsies (n=321; 90%). The three most commonly observed histopathological groups were the connective tissue hyperplasia (n=90; 25.2%), epithelial dysplasia and neoplasia (n=68; 19%) and salivary gland cysts/mucocele (n=56; 15.7%). The top five most frequent diagnoses were mucocele (n=56; 15.7%), squamous cell carcinoma (n=45; 12.6%), epulides (n=31; 8.7%), pyogenic granuloma (n=25; 7.0%) and fibroepithelial polyp (n=19; 5.3%). Oro-facial malignancies made up almost one-fifth of all diagnoses and squamous cell carcinoma was the most common sub-type. Lymphomas in the oro-facial region (n=8; 11.4%) were more common than basal cell carcinoma (n=7; 10%) and salivary gland malignancies (n=6; 8.5%). Epithelial jaw cysts consisted of 8.7% (n=31) of all diagnoses, where inflammatory types were more common than the developmental types. Odontogenic tumours consisted of 5.6% (n=20) of all diagnoses and ameloblastoma was the predominant type.