Original Articles
The immunohistochemical response of the rat periodontal ligament endothelium to an inflammatory stimulus
Andrew Toms, Bren Gannon, Colin Carati
Australian Orthodontic Journal 2000; 16(2): 61-8
Anterior open-bite malocclusion: stability of maxillary repositioning using rigid internal fixation
Premjit Arpornmaeklong, Andrew A. C. Heggie
Australian Orthodontic Journal 2000; 16(2): 69-81
A comparison of two methods of assessing orthodontic treatment need in the mixed dentition: DAI and IOTN
Mark Johnson, Michael Harkness, Paul Crowther, Peter Herbison
Australian Orthodontic Journal 2000; 16(2): 82-7
Ultrastructural identification of cells involved in the healing of intramembranous bone grafts in both the presence and absence of demineralised intramembranous bone matrix
Siew Han Chay, A. Bakr M. Rabie
Australian Orthodontic Journal 2000; 16(2): 88-97
Effectiveness and duration of two-arch fixed appliance treatment
Ming Tak Chew, Andrew Sandham
Australian Orthodontic Journal 2000; 16(2): 98-103
Case Reports
Treatment of an "ankylosed" upper central incisor in the mixed dentition
Robert Cerny
Australian Orthodontic Journal 2000; 16(2): 104-7
Treatment of a severe Class III skeletal discrepancy at an appropriate age
Ken Marshall
Australian Orthodontic Journal 2000; 16(2):108-14
Clinical Investigation
A comparison of retention rates of brackets with thermally-cured and light-cured custom bases in indirect bonding procedures
Peter G. Miles
Australian Orthodontic Journal 2000; 16(2): 115-7
Abstracts
The immunohistochemical response of the rat periodontal ligament endothelium to an inflammatory stimulus
Andrew Toms, Bren Gannon, Colin Carati
Recently, inflammation has been recognised as an important co-requisite to orthodontic tooth movement. When such a reaction is initiated, the process of up-regulation of certain adhesion molecules may occur, resulting in the extravasation of leukocytes. This may stimulate progenitor/precursor pathways and signals that regulate the biological responses resulting in tooth movement. We propose that up-regulation of leukocyte adhesion molecules occurs in response to orthodontic forces, resulting in circulating monocyte attraction, extravasation and differentiation into osteoclasts, which are responsible for bone resorption that results in orthodontic tooth movement. To investigate this hypothesis, it is necessary to determine whether periodontal ligament (PDL) endothelium responds to inflammatory stimuli as other organs do. We studied the normal distribution of endothelial adhesion molecule ICAM-1 within PDL vessels, and then the following exposure to an inflammatory endotoxin. The rat PDL blood vessels expressed ICAM-1 in response to the inflammatory stimulus, similar to other organs, suggesting that the inflammatory responses are similar. Whether and where in the PDL microvascular bed orthodontic forces cause up-regulation of ICAM-1 needs to be established.
Received for publication: September 1999
Accepted: April 2000
Aust Orthod J 2000: 16(2): 61-8
Anterior open-bite malocclusion: stability of maxillary repositioning using rigid internal fixation
Premjit Arpornmaeklong, Andrew A. C. Heggie
A retrospective cephalometric study was performed to investigate the stability of 37 non-growing anterior open-bite cases using mini-plate rigid fixation. The sample was divided into two groups: Group A: maxillary repositioning alone (17 cases) and Group B: bimaxillary surgery (20 cases). Tracings were performed pre-operatively (T1), immediately post-operatively (T2) and at a minimum of one year follow-up (T3) (12-90 months).
In Group A, the maxilla was advanced (3.8 ± 2.8 mm, p < 0.01) and superiorly repositioned at PNS (2.8 ± 2.3 mm, p < 0.001). In Group B, the maxilla was advanced (3.5 ± 3.0 mm, p < 0.01) and superiorly repositioned at PNS (3.7 ± 1.8 mm, p < 0.001); and the mandible (11.7 ± 3.8 mm, p < 0.001), with no significant change in the vertical plane (p > 0.05).
Late relapse due to condylar remodelling or resorption was found as a cause of large horizontal relapse (8.0 < x < 14.0 mm) in three cases (15%), the amount being associated with the amount of operative advancement (r = 0.7m, r-sq = 4%, p < 0.01).
It was concluded that the correction of anterior open bite by posterior repositioning of the maxilla using rigid fixation is a stable procedure during the follow-up period, and that in bimaxillary cases, post-operative stability depends largely on the stability of the mandibular advancement, which in turn relates to the amounts of advancement, the pre-operative anterior open bite and the mandibular plane angle.
Received for publication: May 1999
Accepted: January 2000
Aust Orthod J 2000; 16: 69-81
A comparison of two methods of assessing orthodontic treatment need in the mixed dentition: DAI and IOTN
Mark Johnson, Michael Harkness, Paul Crowther, Peter Herbison
This paper assesses the unmet orthodontic treatment need in a random sample of 10-year-old schoolchildren, using two indices: the Dental Aesthetic Index (DAI) and the Index of Orthodontic Treatment Need (IOTN). The DAI scores were adjusted by omitting the missing teeth component of the index because many children were in the mixed dentition with unerupted permanent teeth. Although both indices assessed the same number of children with malocclusions requiring orthodontic treatment, not all were ranked similarly by each index.
Received for publication: February 1999
Accepted: January 2000
Aust Orthod J 2000; 16(2): 82-7
Ultrastructural identification of cells involved in the healing of intramembranous bone grafts in both the presence and absence of demineralised intramembranous bone matrix
Siew Han Chay, A. Bakr M. Rabie
Alveolar bone defects are conditions that impede the progress of orthodontic treatment. This study compared the mechanics of the healing of autogenous intramembranous (IM) bone grafts and grafts comprising a mixture of IM and demineralised bone matrix of autogenous intramembranous origin (DBMIM), in an attempt to determine the reliability of each material. Thirty-two New Zealand white rabbits had a single defect created in their skull. Sixteen were grafted with IM bone alone (Group 1: autogenous IM), and the other 16 had a combined graft of composite IM sandwiched between two layers of DBMIM (Group II: composite IM-DBMIM). A third group (Group III) of eight rabbits each had two defects created in their skull; one defect was left empty (A: passive control) and the other filled with rabbit-skin collagen (B: active control). In Groups I and II, inflammatory cells were found to be present on Days 1 and 2 of tissue retrieval. The appearance of the mesenchymal cells and preosteoblasts, osteoblasts and osteocytes was earlier (Day 3) in Group II than in Group I (Day 5). In both groups, preosteoblasts, osteoblasts and osteocytes were observed with no cartilage at the immediate stage. In conclusion, autogenous IM bone grafts and IM bone grafts in the presence of DBMIM healed through an osteogenic ossification route.
Received for publication: May 1999
Accepted: March 2000.
Aust Orthod J 2000; 16(2): 88-97
Effectiveness and duration of two-arch fixed appliance treatment
Ming Tak Chew, Andrew Sandham
The aims of this study were to determine the effectiveness and duration of single-phase two-arch fixed appliance treatment and to evaluate factors that may influence these two variables. Data were collected from 177 consecutively completed cases at the Orthodontic Department, Government Dental Clinic, Singapore, during a three-month period. Pre-treatment and post-treatment models were assessed using the Peer Assessment Rating (PAR) index. The results showed that two-arch fixed appliance treatment reduced the malocclusions on average by 77.80 per cent over a period of 25 months. Multiple regression techniques revealed that 22 per cent of the variability in treatment effectiveness could be explained by the pre-treatment PAR score, the age at the start of treatment, the frequency of office visits and whether or not the treatment involved extractions. The variation in treatment duration was due to the frequency of office visits, the pre-treatment PAR score and whether or not the treatment involved extractions or headgear.
Received for publication: January 1999
Accepted: December 1999
Aust Orthod J 2000; 16(2): 98-103
Case Report
Treatment of an "ankylosed" upper central incisor in the mixed dentition
Robert Cerny
A ten-year-old boy presented with an unerupted upper right central incisor (UR1). An OPG radiograph showed a supernumerary tooth lying over its crown, preventing its eruption. Standard orthodontic treatment involving removal of the supernumerary tooth, attaching a gold chain to the UR1 and treatment with fixed orthodontic appliances failed to bring the tooth down, until it was found that tough fibrous gingival tissue entwined in the gold chain had "ankylosed" the tooth. Once this tissue had been removed and the wound packed open, the tooth was brought down successfully into occlusion.
Received for publication: March 2000
Accepted: May 2000
Aust Orthod J 2000; 16(2): 104-7
Case Report
Treatment of a severe Class III skeletal discrepancy at an appropriate age
Ken Marshall
This case report was one of the winners of the Australasian Edgewise Study Group awards for 1999.
The 13-year-old female presented for correction of a severe Class III malocclusion with a Class III skeletal pattern. This was considered an appropriate age for treatment as earlier treatment may have been subject to relapse because significant facial growth may have occurred after treatment, and because treatment at a later age may have required orthognathic surgery. Initially, maxillary expansion was provided to widen the maxilla and to free the circum-maxillary sutures. Maxillary protraction headgear was worn to perform sagittal skeletal improvement. Fixed orthodontic appliances were placed to align the dentition and Class III elastics were used to improve intercuspation and stability.
Patient cooperation was crucial for success. The skeletal changes provided rewards that included significantly improved facial and dental appearance, while avoiding orthognathic surgery.
Received for publication: December 1999
Accepted: March 2000
Aust Orthod J 2000; 16(2):108-14
Clinical Investigation
A comparison of retention rates of brackets with thermally-cured and light-cured custom bases in indirect bonding procedures
Peter G. Miles
This study compared the retention rates of thermally-cured (TC) and light-cured (LC) custom bases attached to metal mini-diamond brackets and clear Spirit MB brackets, when used in indirect bonding procedures. The custom base comprised either the light-cured or thermally-cured material attached to the bracket base and prepared in the laboratory, the whole unit later being bonded to the natural teeth. Thirty consecutively treatment patients had fixed appliances fitted in both arches, with Spirit MB brackets on the maxillary anterior teeth, and metal brackets on the maxillary posterior and all mandibular teeth. All brackets were bonded using either the LC or TC method. All procedures and treatment was by the same operator, using identical techniques. Observation was for six months. All bonding failures were recorded. The results indicated no significant differences in the retention rates of either of the custom-base materials when used with metal brackets. However, the spirit MB brackets exhibited a significantly higher bonding failure rate when a TC customer base was used. It was therefore concluded that either material could be used in the indirect bonding of metal brackets, and that LC custom bases should be used in the indirect bonding of Spirit MB brackets.
Received for publication: March 2000
Accepted: May 2000
Aust Orthod J 2000; 16(2): 115-7