ABSTRACT
This study aimed to investigate the general mandibular symphysis (MS) shape variation among Class III skeletal base, using geometric morphometric analysis. Pre-treatment lateral cephalometric radiographs of 254 patients aged 11–40 years old, with Class III skeletal base (ANB <1o ) and lower incisor angle (<99o ) were included. Nine-landmarks with x and y coordinates were identified on MS using TPSDig2 software, then exported into Morpho J for shape and statistical analysis. Principal component analysis showed that three main shape dimensions with a total variance of 74.6% represented the majority variation of samples. Procrustes Anova showed the shape of MS in Class III skeletal base to be mainly influenced by gonial angle, incisor inclination and sex (P<0.0001). Canonical variate analysis showed that high gonial angle groups had significantly narrower and elongated MS whereas low gonial angle groups had wider, bulbous and rounded MS (P<0.0001). The ratio of alveolar part to basal part was 1:5 in low gonial angle and 2:3 in high gonial angle. Males had significantly taller MS with narrower B point area compared to females (P<0.0001). Retroclined incisors exhibited taller and retroclined alveolar parts (P<0.0001). The shape of MS in Class III skeletal base varied at the alveolar part, basal part or both and it is influenced by gonial angle, incisor inclination and sex. Hence, understanding the shape variation of MS is important to aid orthodontic treatment planning.
ABSTRACT
The purpose of this study was to assess the feasibility of the use of Index of Orthodontic Treatment Need (IOTN) on labial segment malocclusion in determining the need for orthodontic treatment among 8 to 10-year old children. Convenient sample of one hundred and six (106) children (54 boys and 52 girls) were examined extra and intra-orally. Their skeletal and dental discrepancies were assessed in all three dimension planes. Any presence of mandibular displacement was identified. The IOTN score was determined for each child. Respectively it was found that 39.6%, 49.1% and 11.3% of the children presented with skeletal Class I, Class II and Class III malocclusion(p<0.05). Inter-arch relationship showed a significant difference of the midline condition of the upper arch and the presence of anterior and posterior crossbite (p<0.05). About 17.8% of the children had increased overjet of more than 6 mm. Increased overbite was seen in 55.7% of the children with 7.6% presenting with palatal contact. There was a higher prevalence (57.5%) of crowding in the mandibular arch, while the maxillary arch had a higher prevalence (62.2%) of spacing. More than half (62.2%) of the children were in need of treatment (IOTN Grade 3, 4 and 5).This study showed a high prevalence of labial segment malocclusion among 8 to 10-year-old children which indicate orthodontic intervention. The IOTN is not a suitable index for mixed dentitions to be used for developing occlusion for the population group.
Subject(s)
Child , Index of Orthodontic Treatment Need , MalocclusionABSTRACT
Bone is a specialised connective tissue and together with cartilage forms the strong and rigid endoskeleton. These tissues serve three main functions: scaffold for muscle attachment for locomotion, protection for vital organs and soft tissues and reservoir of ions for the entire organism especially calcium and phosphate. One of the most unique and important properties of bone is its ability to constantly undergo remodelling even after growth and modelling of the skeleton have been completed. Remodelling processes enable the bone to respond and adapt to changing functional situations. Bone is composed of various types of cells and collagenous extracellular organic matrix, which is predominantly type I collagen (85-95%) called osteoid that becomes mineralised by the deposition of calcium hydroxyapatite. The noncollagenous constituents are composed of proteins and proteoglycans, which are specific to bone and the dental hard connective tissues. Maintenance of appropriate bone mass depends upon the precise balance of bone formation and bone resorption which is facilitated by the ability of osteoblastic cells to regulate the rate of both differentiation and activity of osteoclasts as well as to form new bone. An overview of genetics and molecular mechanisms that involved in the differentiation of osteoblast and osteoclast is discussed.