Status of retained deciduous second molars in subjects with agenesis of second premolars in relation to age.

AIM: To evaluate the presence and status of retained DM2 without permanent successors in relation to age. BACKGROUND: Preservation of retained deciduous second molars (DM2) can be applied to treat congenital absence of second premolars (PM2). However, the consequences of caries and progressing root resorption or infraocclusion may affect their survival. METHODS: Panoramic radiographs of individuals >10 years of age with agenesis of at least one PM2 were evaluated and divided into three groups according to age. The presence and location of retained DM2, caries/restorations, infraocclusion and root resorption were investigated. RESULTS: A total of 131 subjects with PM2 agenesis were included (mean age: 13 years 11 months). The majority were missing one or two PM2. In total, 174 retained DM2 were present (33%), and their incidence was higher in the younger age groups. Caries/restorations were found in 88 (50.6%) and infraocclusion in 21 (12%) retained DM2. The roots were resorbed mostly for ½ of the root length (35%). CONCLUSION: Long-term prognosis of retained DM2 without permanent successors seems uncertain, especially within the younger age group. In individuals older than 17 years, the prognosis for a healthy DM2 is favorable, if no distinct infraocclusion or extensive root resorption is present.

Autotransplantation of premolars to replace maxillary incisors: a comparison with natural incisors.

The published literature contains no comprehensive studies that compare the outcome of premolar autotransplantation to the maxillary anterior region with natural incisors in the same patients. This article describes the gingival and periodontal conditions around premolars transplanted to the maxillary incisor region, subsequent to restoration. Forty-five premolars autotransplanted to the maxillary incisor region in 40 adolescent patients were evaluated after a mean observation period of 4.0 years. Mean age at surgery was 11.0 years. Established clinical criteria were used to assess tooth mobility, plaque and gingival indexes, probing pocket depth, and percussion. Recession and hyperplasia of interproximal gingival papillae were assessed according to a recently proposed index. Standardized radiography was used to evaluate presence of pathosis, pulp obliteration, root length, and crown-root ratios. Clinical variables for transplants did not differ from those of the natural incisors, except for increased mobility and more plaque in a few transplanted premolars. The interproximal gingival papillae adjacent to all transplanted teeth were normal or slightly hyperplastic. Radiographically, all transplants showed varying degrees of pulp obliteration, but no signs of pathosis. Crown-root ratios were similar for natural and transplanted teeth as were distances from cementoenamel junction to marginal bone. The overall status of the transplanted premolars and surrounding tissues indicated that this treatment modality may be recommended when maxillary incisors are missing in adolescents. In addition, tooth transplantation represents an inherent potential for bone induction and reestablishment of a normal alveolar process.

The effect of long-term water storage on the tensile strength of orthodontic brackets bonded with resin-reinforced glass-ionomer cements.

The purpose of this study was to evaluate in vitro the effect of water storage on the tensile bond strength of orthodontic brackets bonded with Vitremer and Fuji II LC resin-reinforced glass-ionomer cements. Seventy-two extracted human premolars were randomly divided into 6 groups and the bonding strengths of the resin-reinforced glass-ionomer cements were compared to control groups bonded with Concise composite resin at 24 hours and 9 months. The brackets were bonded on prepared teeth and a tensile load was applied to dislodge the brackets held in a special device from Lloyd 1000R testing machine. The effects of duration of water exposure, type of bonding material and interaction between long-term water exposure and type of bonding material on the bonding strength were described using the Weibull regression model. The mean tensile bond strength of resin-reinforced glass-ionomers after 24 hours water storage was significantly lower than the mean of the control samples. The results of this study showed no effect of water exposure on the tensile bond strength of brackets bonded with Vitremer glass-ionomer cement. The mean bonding strength of brackets bonded with Fuji II LC without enamel pre-conditioning significantly increased after 9-months water storage as compared to Fuji samples exposed to water for 24 hours. The results of this investigation allow to conclude: 1. Long-term water storage had not decreased the bond strength of resin-reinforced glass-ionomers applied as orthodontic adhesives, 2. Weibull regression model is an adequate and flexible tool to evaluate the bonding properties of dental materials.

Cariostatic effect of a light-cured, resin-reinforced glass-ionomer for bonding orthodontic brackets in vivo. A combined study using microradiography and confocal laser scanning microscopy.

The aim of this study was to evaluate in vivo the cariostatic potential of the resin-reinforced glass-ionomer (Vitremer core build-up restorative; 3M Dental Product Division) when used as a bonding agent for orthodontic brackets. The mineral distribution and topography of the enamel surface adjacent to the bracket base was determined by quantitative microradiography (TMR) and confocal laser scanning microscopy (CLSM). The study was designed in split-mouth technique using 9 pairs of premolars to be extracted for orthodontic reasons. One tooth of each pair was bonded with the resin-reinforced glass-ionomer, and the control contralateral premolar with the non-fluoridated composite (Concise, 3M Dental Products Division). After 4 weeks all teeth were extracted and stored until analysis. The lesion depths and mineral loss values in enamel adjacent to brackets bonded with Vitremer were significantly lower than in teeth bonded with the composite, indicating that the resin-reinforced glass-ionomers significantly reduced caries lesion development in vivo. CLSM images show a severe cariogenic challenge around orthodontic brackets and support TMR measurements.

Dentistry in Poland.

A visit to the Orthodontic Institute in Warsaw was kindly sponsored by American Orthodontics in order to enable a straight wire typodont course to be conducted. The entire orthodontic department turned out for the course, and it proved to be a stimulating and enjoyable few days. This report details the state of orthodontics in Poland and aims to outline various similarities and differences between dental training in Warsaw and in Great Britain, both at undergraduate and postgraduate levels.