Effects of diabetes on tooth movement and root resorption after orthodontic force application in rats.

OBJECTIVE: To investigate the effects of diabetes on orthodontic tooth movement and orthodontically induced root resorption in rats. SETTING AND SAMPLE POPULATION: Twenty-three 10-week-old male Sprague-Dawley rats divided into control (n = 7), diabetes (n = 9), and diabetes + insulin (n = 7) groups. MATERIALS AND METHODS: Diabetes was induced by administering a single intraperitoneal injection of streptozotocin. Rats with a blood glucose level exceeding 250 mg/dl were assigned to the diabetes group. Insulin was administered daily to the diabetes + insulin group. A nickel-titanium closed-coil spring of 10 g was applied for 2 weeks to the maxillary left first molar in all rats to induce mesial tooth movement. Tooth movement was measured using microcomputed tomography images. To determine the quantity of root resorption, the mesial surfaces of the mesial and distal roots of the first molar were analyzed using both scanning electron microscopy and scanning laser microscopy. RESULTS: After 2 weeks, the amount of tooth movement in the diabetic rats was lower than that in the control rats. Root resorption was also significantly lower in the diabetic rats. These responses of the rats caused by diabetes were mostly diminished by insulin administration. CONCLUSIONS: Diabetes significantly reduced orthodontic tooth movement and orthodontically induced root resorption in rats. The regulation of blood glucose level through insulin administration largely reduced these abnormal responses to orthodontic force application.

Nasopharyngoscopic evaluation of oral appliance therapy for obstructive sleep apnoea.

This study aimed to explore the effect of mandibular advancement splints (MAS) on upper airway anatomy during wakefulness in obstructive sleep apnoea (OSA). Patients commencing treatment for OSA with MAS were recruited. Response to treatment was defined by a >or=50% reduction in the apnoea/hypopnoea index. Nasopharyngoscopy was performed in the supine position. Nasopharyngoscopy was performed in 18 responders and 17 nonresponders. Mandibular advancement caused an increase in the calibre of the velopharynx (mean+/- sem +40+/-10%), with relatively minor changes occurring in the oropharynx and hypopharynx. An increase in cross-sectional area of the velopharynx with mandibular advancement occurred to a greater extent in responders than nonresponders (+56+/-16% versus +22+/-13%; p<0.05). Upper airway collapse during the Müller manoeuvre, relative to the baseline cross-sectional area, was greater in nonresponders than responders in the velopharynx (-94+/-4% versus -69+/-9%; p<0.01) and oropharynx (-37+/-6% versus -16+/-3%; p<0.01). When the Müller manoeuvre was performed with mandibular advancement, airway collapse was greater in nonresponders than responders in the velopharynx (-80+/-11% versus +9+/-37%; p<0.001), oropharynx (-36+/-6% versus -20+/-5%; p<0.05) and hypopharynx (-64+/-6% versus -42+/-6%; p<0.05). These results indicate that velopharyngeal calibre is modified by MAS treatment and this may be useful for predicting treatment response.

Nano-indentation characterisation of natural carious white spot lesions.

The aim of this paper was to characterise the mechanical properties (MPs) and microstructural features of natural enamel white spot lesions (WSLs) using nano-indentation. Five natural WSLs from 4 extracted sound premolar teeth were cross-sectioned. Elastic modulus and hardness were measured systematically across the WSLs at intervals of 25 and 50 microm. The WSLs showed a large reduction in MPs compared to sound counterpart: elastic modulus was up to 83% lower (77.0 +/- 2.2 to 13.4 +/- 2.1 GPa) and hardness up to 91% lower (3.39 +/- 0.41 to 0.29 +/- 0.07 GPa). The intact surface layer above WSLs had less than 34% reduction in MPs. Detailed MP measurements were mapped as two-dimensional contour plots. Typically, WSLs displayed steep MP gradients at the lesion boundary and more uniform MPs with isolated variations in the lesion body. Despite the large reduction in MPs, the microstructure of WSLs remained intact. We postulate that loss of mineral and change of the hierarchical microstructure at the crystallite level contributed to the overall MPs of WSLs.

Myofunctional therapy and prefabricated functional appliances: an overview of the history and evidence.

Malocclusion represents the clinically observable endpoint of numerous genetic and environmental influences. Oral Myofunctional Therapy (OMT) aims to treat malocclusions by improving the oral environment through re-education of musculature and respiratory patterns. Although the concept of OMT has existed since the early part of the 20th Century, many of its purported benefits for the treatment of malocclusion remain undemonstrated in the scientific literature. However, a more recent application of OMT for the treatment of Obstructive Sleep Apnoea (OSA) suggests some benefits, although more research is needed to clarify this effect. Prefabricated functional appliances (PFAs) are sometimes advocated as part of myofunctional training programs. In the past decade, controlled clinical investigations have demonstrated that PFAs can improve Class II Division 1 malocclusions in compliant patients. Compared with traditional functional appliances, PFAs might be more cost effective; however, this must be balanced against compliance problems and evidence suggesting that other types of functional appliances might give better treatment results in a comparable time frame.

Distal molar movement using the pendulum appliance. Part 1: Clinical and radiological evaluation.

Intra-arch distal molar movement techniques have recently assumed an important role in clinical orthodontics. In this study, the dental and skeletal effects of the pendulum appliance, applying 200 to 250 g of force to the molars in 13 patients (age range 8 years to 13 years 5 months) were evaluated by means of cephalometric radiographs. The results showed that the pendulum appliance moved the molars distally without creating dental or skeletal bite opening and with little incisor anchorage loss. However, important molar tipping should be taken into consideration when using this appliance.

Distal molar movement using the pendulum appliance. Part 2: The effects of maxillary molar root uprighting bends.

A clinical study was recently undertaken to evaluate the dental and skeletal effects of the pendulum appliance (PA). In the present study, the appliance was modified by incorporating an uprighting bend into the distalizing spring during the second phase of treatment to avoid excessive distal tipping of the maxillary molars. The sample consisted of 20 patients: 8 females and 12 males, mean age 13.11 +/- 1.10 years. Eight of the patients were subjected to a slow rate of maxillary expansion. Measurements were obtained from cephalometric headfilms prior to (T1) and the day of removal (T2) of the PA. Treatment changes were analyzed and compared with the previous study. The PA with uprighting bends led to reduced molar tipping without significantly changing the effects of the PA, with the exceptions of 0.62 mm more anchorage loss of the maxillary incisor edge and increased treatment time. There was no significant difference in anchorage loss between the patients with and without maxillary expansion.

Cephalometric norms for the Chinese: a compilation of existing data.

The intention of this paper is to compile Chinese cephalometric norms for a more objective orthodontic diagnosis of Chinese patients so that their orthodontic treatment may be better planned. Studies on cephalometric norms of Chinese and subjects of Chinese descent were reviewed. Some important studies were available only in the Chinese journals and they were especially procured and translated for this purpose. A normal range of anteroposterior apical base differences, concomitant nterincisal inclinations and locations, were derived from different Chinese groups and were tabulated. The differences between Chinese and Caucasian norms are discussed. A distinctive craniofacial and dental pattern of the people of Chinese origin was found and is reflected in the cephalometric measurements. Compared with Caucasian norms, Chinese norms have skeletal, dental and soft-tissue variations. The Chinese have a shorter cranial base and a larger ANB. The Chinese dentition demonstrates greater bimaxillary-alveolar protrusion, with a decreased interincisal angle. The Chinese soft-tissue profile shows a less prominent nose, with a less obtuse nasolabial angle, and more protrusive lips.

Finishing occlusion in Class II or Class III molar relation: therapeutic Class II and III.

The most frequent extraction regime consists of the removal of upper and lower premolars. Depending on anchorage requirements, camouflage treatment options, surgical intervention, or the absence of teeth in only one arch, it may become necessary to finalize the occlusion with a one-dental-unit discrepancy between the upper and lower dental arches. Guidelines are presented for finishing occlusions in Class II or Class III molar relation.

Profile of orthodontic services provided in private practice by general practitioners and specialist orthodontists for an insured population.

In Australia, the proportion, volume and type of orthodontic care provided by general practitioners and orthodontists are largely unknown. The overall objective of this study was to create a profile of orthodontic services provided by general practitioners and orthodontists for a cohort of insured patients using private practices in New South Wales, Australia, from 1st January 1992 to 31st December 1995. Data were derived from claims records submitted by members of a health insurance fund for rebates for fees paid to private practitioners for orthodontic services they received during the study period. Distribution of the volume and type of service provided by general practitioners and orthodontists was compared using the Chi-squared test. Statistical significance was taken at the 5 per cent level. Orthodontic services were provided predominantly by orthodontists (80%). Fixed orthodontic treatment was provided almost exclusively (91%) by orthodontists. The majority of removable appliance services was provided by general practitioners. Orthodontists provided more orthodontic services in the capital city and other metropolitan areas, whereas general practitioners provided more orthodontic services in rural areas. Orthodontists provided more services to members in the highest socio-economic group, whereas general practitioners provided more services to members in the lowest socio-economic group.

Varying treatments of Class II malocclusions: two case reports.

Two female patients, JH aged 13 years 5 months and CN, aged 13 years 10 months, presented at the Sydney University Orthodontic Clinic, Australia. Patient JH complained that her lower teeth were "too far back behind her top teeth". She was treated using the Speed Appliance. Patient CN complained that her teeth were "crooked". The main point of interest of her case is the mechanics used following the extraction of her four first molar teeth. Both patients were keen to improve their appearance.

The biology of TMJ growth modification: a review.

Several studies have indicated a positive response of the temporomandibular joint (TMJ) to mandibular advancement, while others have reported that TMJ adaptive responses are non-existent and negligible. Controversy continues to grow over the precise nature of skeletal changes that occur during mandibular growth modification, due to an apparent lack of tissue markers required to substantiate the precise mechanism by which this is occurring. However, evidence suggests that orthopedic forces clinically modify the growth of the mandible. To further our knowledge about the effect of orthopedic treatment on the TMJ, it is necessary that we understand the biologic basis behind the various tissues involved in the TMJ's normal growth and maturation. The importance of this knowledge is to consider the potential association between TMJ remodeling and mandibular repositioning under orthopedic loading. Considerable histologic and biochemical research has been performed to provide basic information about the nature of skeletal growth modification in response to mandibular advancement. In this review, the relevant histochemical evidence and various theories regarding TMJ growth modification are discussed. Furthermore, different regulatory growth factors and tissue markers, which are used for cellular and molecular evaluation of the TMJ during its adaptive response to biomechanical forces, are underlined.

Clinical guidelines for oral appliance therapy in the treatment of snoring and obstructive sleep apnoea.

The purpose of this review is to provide guidelines for the use of oral appliances (OAs) for the treatment of snoring and obstructive sleep apnoea (OSA) in Australia. A review of the scientific literature up to June 2012 regarding the clinical use of OAs in the treatment of snoring and OSA was undertaken by a dental and medical sleep specialists team consisting of respiratory sleep physicians, an otolaryngologist, orthodontist, oral and maxillofacial surgeon and an oral medicine specialist. The recommendations are based on the most recent evidence from studies obtained from peer reviewed literature. Oral appliances can be an effective therapeutic option for the treatment of snoring and OSA across a broad range of disease severity. However, the response to therapy is variable. While a significant proportion of subjects have a near complete control of the apnoea and snoring when using an OA, a significant proportion do not respond, and others show a partial response. Measurements of baseline and treatment success should ideally be undertaken. A coordinated team approach between medical practitioner and dentist should be fostered to enhance treatment outcomes. Ongoing patient follow-up to monitor treatment efficacy, OA comfort and side effects are cardinal to long-term treatment success and OA compliance.

Dissecting the role of the S1P/S1PR axis in health and disease.

Sphingosine-1-phosphate (S1P) is a pleiotropic sphingophospholipid generated from the phosphorylation of sphingosine by sphingosine kinases (SPHKs). S1P has been experimentally demonstrated to modulate an array of cellular processes such as cell proliferation, cell survival, cell invasion, vascular maturation, and angiogenesis by binding with any of the five known G-protein-coupled sphingosine 1 phosphate receptors (S1P1-5) on the cell surface in an autocrine as well as a paracrine manner. Recent studies have shown that the S1P receptors (S1PRs) and SPHKs are the key targets for modulating the pathophysiological consequences of various debilitating diseases, such as cancer, sepsis, rheumatoid arthritis, ulcerative colitis, and other related illnesses. In this article, we recapitulate these novel discoveries relative to the S1P/S1PR axis, necessary for the proper maintenance of health, as well as the induction of tumorigenic, angiogenic, and inflammatory stimuli that are vital for the development of various diseases, and the novel therapeutic tools to modulate these responses in oral biology and medicine.

Effects of mechanical stimuli on adaptive remodeling of condylar cartilage.

Trabecular bone has been shown to be responsive to low-magnitude, high-frequency mechanical stimuli. This study aimed to assess the effects of these stimuli on condylar cartilage and its endochondral bone. Forty female 12-week-old C3H mice were divided into 3 groups: baseline control (killed at day 0), sham (killed at day 28 without exposure to mechanical stimuli), and experimental (killed following 28 days of exposure to mechanical stimuli). The experimental group was subjected to mechanical vibration of 30 Hz, for 20 minutes per day, 5 days per week, for 28 days. The specimens were analyzed by micro-computed tomography. The experimental group demonstrated a significant decrease in the volume of condylar cartilage and also a significant increase in bone histomorphometric parameters. The results suggest that the low-magnitude, high-frequency mechanical stimuli enhance adaptive remodeling of condylar cartilage, evidenced by the advent of endochondral bone replacing the hypertrophic cartilage.