Midpalatal implants vs headgear for orthodontic anchorage--a randomized clinical trial: cephalometric results.

INTRODUCTION: The purpose of this study was to compare the clinical effectiveness of the midpalatal implant as a method of reinforcing anchorage during orthodontic treatment with that of conventional extraoral anchorage. This was a prospective, randomized, clinical trial at Chesterfield and North Derbyshire Royal Hospital NHS Trust and the Charles Clifford Dental Hospital, Sheffield, in the United Kingdom. METHODS: Fifty-one orthodontic patients between the ages of 12 and 39, with Class II Division 1 malocclusion and absolute anchorage requirements, were randomly allocated to receive either a midpalatal implant or headgear to reinforce orthodontic anchorage. The main outcome was to compare the mesial movement of the molars and the incisors of the 2 treatment groups between the start and the end of anchorage reinforcement as measured from cephalometric radiographs. RESULTS: The reproducibility of the measuring technique was acceptable. There were significant differences between T1 and T2 in the implant group for the positions of the maxillary central incisor (P <.001), the maxillary molar (P = .009), and the mandibular molar (P <.001). There were significant differences between T1 and T2 in the headgear group for the positions of the mandibular central incisor (P <.045), the maxillary molar (P <.001), and the mandibular molar (P <.001). All skeletal and dental points moved mesially more in the headgear group during treatment than in the implant group. These ranged from an average of 0.5 mm more mesially for the mandibular permanent molar to 1.5 mm more mesially for the maxillary molar and the mandibular base. No treatment changes between the groups were statistically significant. CONCLUSIONS: Midpalatal implants are an acceptable technique for reinforcing anchorage in orthodontic patients.

The effect of stretching on the release of fluoride from fluoridated elastomeric ligatures.

INTRODUCTION: The aim of this in-vitro investigation was to determine whether stretching increases the amount of fluoride released from fluoridated elastomeric ligatures. METHODS: Ten groups of 4 fluoridated elastomeric ligatures stretched over edgewise premolar brackets were compared with 10 groups of 4 ligatures that were not stretched over brackets. Each group was placed in individual polyethylene bottles containing 1 mL of distilled water and maintained at 37 degrees C in an incubator. A polyethylene bottle containing only distilled water and 4 brackets was used as the control. The fluoride content of the samples was determined once a day for 7 days and regularly thereafter up to 196 days. A fluoride-ion selective electrode coupled to an analyzer was used to determine the fluoride content of the solutions. The sample solutions were changed 24 hours before readings to prevent the results from being cumulative. RESULTS: The fluoride-ion release for each of the groups was calculated and expressed as total fluoride release in micrograms of fluoride per day per milliliter per elastomer. During the first month in solution, the stretched fluoridated elastomers released approximately 32 microgF.day/mL and the unstretched speciments released 30 microgF.day/mL. This represents a 7% increase in fluoride release, which was statistically significant (P = .007). Over the entire test period (196 days), the modules stretched over the brackets released about 13% more fluoride. This was also a statistically significant difference (P = .001). CONCLUSIONS: Stretching increases the concentration and amount of fluoride released from fluoridated elastomeric ligatures.