Jon Årtun

Clinical trials with crystal growth conditioning as an alternative to acid-etch enamel pretreatment

It has been claimed that different ion solutions containing sulfate induce crystal growth and might be a better alternative than conventional acid etching for enamel pretreatment in bracket bonding. It should thus combine optimal bond strength with easy and quick debonding. Two clinical experiments were performed to test this hypothesis. The first experiment dealt with the debonding procedure. Following conditioning with dilute sulfuric acid which contained sodium sulfate (to be termed solution A) on one side of the mouth and etching with 37% phosphoric acid on the other, brackets were bonded on the maxillary and mandibular incisors of twenty dental nurse students. Debracketing and a subsequent cleanup procedure were performed after 2 days. The mode of loosening was mainly between the enamel surface and adhesive on the crystal-growth-conditioned teeth and between the bracket mesh and adhesive on the teeth etched with phosphoric acid. This difference in mode of loosening was statistically significant (P less than 0.001). In the second experiment, which dealt with the clinical bond strength, 250 brackets were bonded in forty patients. One side served as a control and was conventionally acid etched. On the experimental side conditioning was done with solution A in thirty patients. In ten patients, 10% phosphoric acid was added to the dilute sulfuric acid used (to be termed solution B). Failure rates and modes of failure were recorded for a 6-month period.(ABSTRACT TRUNCATED AT 250 WORDS)

Periodontal status of mandibular incisors following excessive proclination A study in adults with surgically treated mandibular prognathism

The present study was undertaken to examine whether excessive proclination of mandibular incisors results in gingival retraction. In patients with surgically treated mandibular prognathism, 29 with more than 10 degrees proclination of mandibular incisors and 33 with minimal change in incisor inclination during presurgical orthodontic phase were selected. A total of 21 and 19 patients, respectively, could meet for a clinical follow-up examination including Visible Plaque Index, Gingival Bleeding Index, probing pocket depth, and length of supracrestal connective tissue attachment. Study models and intraoral color slides were also made. The mean postoperative times at this examination were 7.8 (SD 2.5) and 8.1 (SD 2.8) years, respectively. Clinical crown height was measured on the study models taken before and after appliance therapy, at the 3-year postoperative control (check) and at the follow-up examination. The number of teeth with recession was determined from the color slides taken at the same intervals; the thickness of the symphysis was measured on the cephalograms taken before treatment. The results demonstrated significantly more increase in clinical crown height and significantly more teeth developing recession both during appliance therapy and during the period from removal of appliance to the 3-year postoperative control in the patients with excessive proclination than in the patients with minimal change in incisor inclination. The correlation coefficient between width of symphysis and increase in clinical crown height in patients with excessive proclination was statistically significant. Only minimal changes were observed from 3 years postoperatively to the follow-up examination. No differences in clinical measurements were observed between the groups and bone dehiscences were not found.

The effect of orthodontic treatment on periodontal bone support in patients with advanced loss of marginal periodontium

Loss of periodontal bone support was examined in 24 patients orthodontically treated for pathologic tooth migration in one jaw. Prior to orthodontic realignment of the front teeth, the patients had received periodontal treatment. Active appliance therapy was not given until inflammation was eliminated and the patients demonstrated a high level of oral hygiene. A 0.020-inch spiral wire was bonded to each adjacent realigned tooth for retention. The levels of marginal bone of the front teeth in the treated and untreated jaws were measured in percentage of maximum bone height on periapical radiographs made before and after treatment. Relapse was evaluated from study models. Mean averaged loss of periodontal bone from the period before to after orthodontic treatment was 4.94% (SD 4.03, P less than 0.001) and 2.69% (SD 3.66, P less than 0.001) of the treated and untreated front teeth, respectively. The mean difference in averaged loss between treated and untreated front teeth was 2.24% (SD 3.28, P less than 0.01). The majority of the sites showed little or no loss. Maximum loss (35%) was observed in one site only. No association was found between initial bone loss and bone loss during orthodontic treatment. Spaces from 0.1 to 1.8 mm opened up adjacent to the retainer in seven patients. Relapse within the retained segment was associated with failures of the retainer. Of the 19 patients who had been in retention for more than 4 months (mean 16.0, SD 12.1), ten failures were recorded in nine patients. The failure mode was loosening of one or two teeth between wire and composite.

Caries and periodontal reactions associated with long-term use of different types of bonded lingual retainers

An investigation was carried out (1) to test the tendency of different types of bonded retainers to accumulate plaque and calculus and (2) to find out whether long-term use of bonded retainers caused any damage to the teeth involved. Two test groups of patients--one with 3-3 retainers made of 0.032-inch spiral wire, and the other with 3-3 retainers made of 0.032-inch plain wire--and a reference group of persons without 3-3 retainers were compared. Also, a test group of patients with retainers made of flexible spiral wire (0.0195 inch) bonded lingually to each anterior tooth in the maxilla was compared to a reference group of patients with retention plates in the maxilla. All the persons selected had received routine orthodontic treatment with a multibonded edgewise light wire technique and had been out of active treatment for 1 to 8 years. Different indices were used to score accumulation of plaque and calculus, prevalence of caries, and periodontal reactions. The findings indicated that there was no basis on which to claim that retainers made of spiral wire accumulated more plaque and calculus than retainers made of plain wire. The presence of a bonded lingual retainer and the occasional accumulation of plaque and calculus gingival to the retainer wire after long-term use caused no apparent damage to the hard and soft tissues adjacent to the wire.

Clinical and histological features observed during arrestment of active enamel carious lesions in vivo.

The aim of the present study was to examine clinical and histological events taking place in vivo during the initial period of arrestment of active enamel carious le sions. For this purpose we developed lesions in vivo during a period of 4 weeks. To ensure plaque accumulation, orthodontic bands with a standardized buccal space were placed on 4 premolars in each of 4 patients undergoing orthodontic treatment. After 4 weeks with local cariogenic challenge, all teeth were debanded and one tooth in each patient extracted as control. All teeth had ‘white spot lesions’ corresponding to the plaque retention area. No professional tooth cleaning was performed. The remaining teeth were extracted 1 2, or 3 weeks after debanding. No fluoride was added during the entire test period and the patients were told to maintain usual oral hygiene. A gradual regression of the lesions in terms of reduction in lesion area and degree of opacity was noted during the following 3 weeks. The polarized light examinations disclosed a prompt reaction to the removal of the bands as no further lesion progress was noted. In addition we observed a decrease in tissue porosity especially in the deepest parts of the lesions while the outer surface appeared more porous than in the base-line lesions.

Surface changes during the arrest of active enamel carious lesions in vivo: A scanning electron microscope study

The present study examines early enamel surface alterations taking place when active carious lesions enter an arrested stage. Orthodontic bands with a standardized space for plaque accumulation were used to produce incipient carious lesions on the buccal surface of all four first premolars of four young adolescents. The premolars were to be extracted for orthodontic reasons. After 4 weeks of local cariogenic challenge, all teeth were debanded. In each patient one tooth was extracted at the time of debanding. The remaining premolars were extracted 1, 2, and 3 weeks after re-exposure to the oral environment. No fluoride was added during the entire test period, and the patients were told to maintain usual oral hygiene. Scanning electron microscope examination of the experimental surface areas disclosed a gradual wearing away of the outermost crystals during the 3 weeks of observation. This was associated with a leveling off of surface irregularities and the development of a multitude of scratches. The observed attrition of the porous surface in the lesion area indicates that functional wear and toothbrushing were responsible for the arrestment by disturbance and removal of bacterial deposits.

Improving the handling properties of a composite resin for direct bonding

Two experiments were performed to improve the handling properties of the Concise enamel bond system for direct bonding. The first study dealt with viscosity. For various reasons, neither the orthodontic nor the restorative Concise composite resins were considered optimal. Trial-and-error mixtures of various combinations of composite paste and liquid resin were made until a paste/paste system with the desired consistency was obtained. By weight analysis and mathematical calculations, it was figured out that the desired consistency could be arrived at by adding about 15 drops of liquid resin to each jar of 16 Gm. composite paste. Thus, diluted Concise had a consistency that allowed exact placement of brackets without subsequent drifting out of position and facilitated removal of excess adhesive outside the bracket pads. The second experiment dealt with working time. The two diluted pastes A and B were mixed in ratios of 1:1, 1:2, and 2:1, and furthermore paste A was mixed with liquid resin B (for superfast set), and the working time in the mouth was examined. The mean working time that was obtained for placement of each bracket in the mouth with equal portions of the 15-drop Concise was about 30 seconds. By varying the ratios, faster or slower working times could easily be obtained (Table I). The advantages of the Concise system as a bonding agent and our experiences with it over the past 10 years are discussed. Detailed clinical recommendations for direct bonding of brackets and lingual retainers with this adhesive are given (Figs. 2 to 8).

Long-term effect of root proximity on periodontal health after orthodontic treatment

The present investigation was done to evaluate the incidence and distribution of root proximity after orthodontic treatment and to test the hypothesis that interproximal areas with thin interdental bone provide less resistance against marginal periodontal breakdown than areas with normal width of bone between the roots. Only adult patients were examined at least 16 years after active orthodontic treatment. The distance between the roots was measured directly on periapical radiographs. Gingival health, level of connective tissue attachment, and clinical scores for bone levels in sites with thin interdental bone and neighboring or contralateral sites with normal width of bone between the roots were compared. Among the 400 patients studied, 25 had unilateral or bilateral areas with root proximity. Root proximity was diagnosed between maxillary central and lateral incisors in 18 patients, between mandibular central and lateral incisors in two patients, and between maxillary lateral incisor and canine, maxillary first and second molars, mandibular canine and first premolar, mandibular first and second premolars, or mandibular first and second molars in only one patient. No statistically significant differences in inflammation, level of attachment, and bone level were observed between root proximity sites and control sites. The results indicate that anterior teeth are not predisposed to more rapid periodontal breakdown when roots are in close proximity. Too few molar sites were included to draw conclusions regarding such areas.

New technique for semipermanent replacement of missing incisors

An investigation was carried out to study the efficiency of a new technique for semipermanent replacement of missing incisors. A flexible system allowing slight physiologic movement of the bridge units was created by bonding an acrylic tooth to the abutments by means of three orthodontic wires, as shown in Figs. 9 to 11. Between June, 1981, and December, 1982, fifty-three bridges of this type were inserted in a sample that was nonselected relative to overbite and overjet. It comprised fifty-one persons 10 to 22 years of age (mean, 16; SD, 3.9). During an observation period of 5 to 22 months (mean, 15; SD, 4.8) ten bridges came loose, giving a failure rate of 18.9% for the whole sample. All the loosened bridges were replacements for missing maxillary central incisors. The thirteen bridges replacing missing maxillary lateral incisors and two bridges inserted in the mandible functioned without problems. There was no correlation between failure rate and overjet and overbite. However, the functional occlusion was of importance. If there was antagonistic contact with the pontic during functional movements, the failure rate was 57.1%. If there was no such contact, however, the failure rate was only 5.4%. This difference was statistically significant. Accumulation of plaque was significantly higher around the abutments than on contralateral surfaces. However, no significant differences in gingival health were recorded. In two persons, dental caries was recorded on the abutment surface facing the pontic.(ABSTRACT TRUNCATED AT 250 WORDS)