Application of light-cure resin-modified glass ionomer cement in orthodontic practice / 中国组织工程研究

ABSTRACT

BACKGROUND: Resin-modified glass ionomer (RMGI) cements have higher bond strength, especially can release fluoride. But there are fewer reports of the clinical application for the prevention of decalcification.OBJECTIVE: To test the benefit from using RMGI cement instead of a conventional composite resin in bracket bonding for patients with malocclusion, and observe bracket-failure rates and decalcification on enamel surfaces at pretreatment and at debonding.DESIGN: Observational and comparative trial.SETTING: The Second Hospital Affiliated to Hebei Medical University.PARTICIPANTS: Forty successive patients (358 teeth) with malocclusion admitted to the Department of Orthodontics in the Second Hospital Affiliated to Hebei Medical University, were selected for the study from July to August in 2002. All the patients (21 females and 19 males, mean age 16 years) had normal and complete anterior teeth, good oral hygiene. There were no obvious differences in bilateral teeth. Informed consents were obtained from all the subjects. The experiment was also approved by the ethical committee of the hospital. Experimental materials were RMGI adhesive (Fuji, GC, Japan, Lot 0005111) and composite resin cement (enamel adhesive of Beijing and Tianjin, Tianjin product, Lot 020402). Brackets produced from Hangzhou 3B and 37% phosphoric acid were used.METHODS: ①Bonding brackets Subjects selected according to random procedure were divided into two groups, each with 20. GroupⅠ The left buccal surfaces bonded with light-cure RMGI were etching for 30 seconds with 37% phosphoric acid, rinsed with water; the right buccal surfaces bonded with composite resin cement were etching for 60 seconds with 37% phosphoric acid, rinsed with water and dried; Group Ⅱ After etching for 30 seconds with 37% phosphoric acid, the right buccal surfaces were rinsed with water and bonded brackets with light-cure RMGI. The left buccal surfaces were bonded brackets with composite resin cement after etching for 60 seconds with 37% phosphoric acid, rinsing with water and drying; Attachment of 0.036-cm NiTi wires with ligature to the brackets was conducted 10 minutes after light-curing. The information about differences in bilateral bonding materials was not told to patients. To ensure an equal bonding materials containing fluoride and minimize the error, all the patients were instructed to use toothpaste containing fluoride, a fluoride mouthwash was not prescribed. The treatment period was 9-26 months (mean 18 months).②Patients were rechecked at intervals of 4 weeks postoperatively. Each bonded tooth was checked for loose or missing brackets, and failures were recorded. A color transparency of anterior teeth area was taken using a standardized photographic technique. The enamel surface conditions were classified at a magnification of ×10. The condition of enamel surface recorded was made according to the scoring system by Geiger before treatment and at debonding.MAIN OUTCOME MEASURES: ①The number and site of bonding failures.②Enamel surface conditions at before treatment and debonding.RESULTS: Forty patients were all involved in the result analysis. Eliminating 4 teeth occurring bond failure and 4 teeth of opposite side at anterior teeth, a total of 232 teeth were evaluated.①The number and sit of bonding failures There was no significant difference between the failure rates of RMGI adhesive and composite resin cement (P > 0.05). Significantly more premolar brackets failed than incisor brackets.②Decalcification of enamel surface At debonding after treatment, the incidence rates of white spots in the surfaces bonded with the RMGI were significantly lower than that in the composite resin (25.9%, 38.8%, P < 0.05).CONCLUSION:The use of RMGI for brackets bonding results in a significant reduction in the incidence of white spot at debonding. Reducing etching time may obtain a similar survival rate with the routine etching time.