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Biomedical subjects

B U Zachrisson

Publications and source records attributed to B U Zachrisson.

At least 37 records · Page 2Linked to original sources
PubMed1984

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)

Acrylic Resins↗
PubMed1983

Incisor position in Scandinavian children with ideal occlusion. A comparison with the Ricketts and Steiner standards.

A cephalometric study, with particular emphasis on incisor pattern, was carried out on thirty Norwegian children with clinically excellent occlusion in the young permanent dentition. The material was selected from a sample of all 12-year-old children within a particular geographic area (Nittedal) of Oslo. The frequency of ideal occlusion was 5.3 percent. A computer-based method of cephalometric analysis was used. The findings indicated that persons with untreated ideal occlusion tended to have a particular facial morphology and dental pattern. More precisely, they were likely to be brachyfacial (horizontal), with somewhat procumbent incisors and a small interincisal angle. Only one patient had dolichofacial (high-angle) characteristics. On average, the lower incisors were 2.5 mm. in front of the APo plane (S.D. 1.7). Remarkably, the lower incisors were not behind the APo plane in any single case with ideal occlusion. Clearly, the lower incisors were clinically significantly more protruded and proclined than those described in previous studies on Scandinavian children and were, in fact, even slightly more procumbent than the Ricketts and Steiner standards. The similarity, with regard to both incisor position and skeletal pattern, of the present findings to some recent studies on American Caucasian children with normal occlusion is stressed. The significance of the observations is discussed in relationship to considerations in orthodontic treatment planning.

Cephalometry↗
PubMed1982

The effect of palatal expansion therapy on the periodontal supporting tissues.

Sixty-one postorthodontic patients were examined to determine the effect of rapid and slow palatal expansion therapy on the periodontal supporting structures located at the buccal aspects on the maxillary first permanent molars. Twenty-eight patients were treated with a rapid maxillary expansion (RME) technique using a tissue-borne, fixed, split acrylic appliance (Fig. 1), while thirty-three underwent slow palatal expansion with a quad-helix appliance (Fig. 3). The two groups demonstrated mean increases in maxillary first molar width of 4.6 mm. and 4.3 mm., respectively. Twenty-eight patients treated with a similar light-wire edgewise technique but no palatal expansion were used as a control. Four periodontal parameters were examined, including level of marginal alveolar bone, attachment levels (from CEJ), probing depths, and width of keratinized gingiva. All measurements were made by the same examiner and recorded to the nearest 0.5 mm., using a specially machined and calibrated periodontal probe. The results demonstrated tht both lateral expansion groups exhibited minimal differences in periodontal condition when compared to the control group. Periodontal status was good in all groups, with average attachment levels being 0.65 mm., 0.36 mm., and 0.51 mm. in the rapid expansion, slow expansion, and control groups, respectively. Although the mean differences were clinically small, individual variation was evident (Fig. 5). Among the few persons who exhibited the more marked periodontal breakdown at the central aspect of the first molars, most were found in the RME group. Except for the type of expansion therapy experienced, none of a number of other orthodontic variables examined demonstrated a statistically significant influence on the periodontal tissues.

Adolescent↗
PubMed1982

Effects of incisor repositioning on monkey periodontium after expansion through the cortical plate.

The anterior teeth of five adult pigtail monkeys were moved lingually to correct a previously induced extreme labial displacement. (Roots had been moved through the labial bone to create bone dehiscence, loss of attachment, and gingival recession.) Eight months later, repositioning was performed with fixed appliances (Fig. 3). The teeth were retained in their more normal arch position for 5 months, after which clinical and histologic measurements were made of several periodontal parameters. The canines were not moved and served as reference teeth. Measurements were made to record changes in the levels of the gingival margin, the mucogingival junction, and the marginal bone relative to a fixed point on the tooth crowns, and the width of keratinized gingiva. Oxytetracycline was administered three times to label areas of osteogenesis in the periodontium. The incisors were retracted lingually a mean of 1.8 mm. The marginal bone level increased (moved coronally) a mean of 2.5 mm. and 3.1 mm. for maxillary and mandibular incisors, respectively (Table II). The tetracycline labels showed that osteogenesis occurred in the periodontium to a significant degree. The anchor canines had a loss of 1.1 mm. marginal bone (moved apically). Effects on gingival clefts and keratinized gingiva were slight. These observations demonstrate that in monkeys reapposition of labial bone can occur in a coronal direction, once teeth in extreme labial position with bone dehiscence and gingival recession are moved to a more normal environment. The effects on the periodontal soft tissues (width of keratinized gingiva, recession, attachment level) were, on the other hand, negligible in this study.

Alveolar Process↗
PubMed1982

The bonded lingual retainer and multiple spacing of anterior teeth.

Retaining tooth positions after orthodontic space closure in cases with multiple spacing of anterior teeth are illustrated by selected cases with varying degrees of bimaxillary spacing initially (Figs. 1-6). In each case, bonded lingual retainers which allowed physiologic tooth movements were used with encouraging results. A meticulous technique for fabrication and bonding of flexible spiral wire retainers is mandatory for clinical success. Detailed recommendations are presented. If similar trials by others confirm the durability and effectiveness of acid-etched lingual retainers, it is expected that the technique can be recommended for routine clinical application.

Adolescent↗
PubMed1980

Enamel cracks in debonded, debanded, and orthodontically untreated teeth.

Using fiber-optic transillumination, a clinical assessment was made of enamel cracks (prevalence, localization, expression, direction) in three groups of adolescents representing debonded, debanded, and orthodontically untreated teeth. The findings indicated that enamel cracks were extremely common in all three groups. Most cracks were not very prominent and could easily be overlooked on routine clinical examination. The majority of cracks were vertical and, with the exception of the mandibular incisors, were most frequently localized in the gingival two-thirds of the facial tooth surfaces. The marked cracks were observed mostly on maxillary canines and central incisors in all groups. Of the few horizontal cracks noted, most were located in maxillary and mandibular central incisors. Clinical implications of the observations are (1) careful bonding and debonding do not result in a significant increase of enamel cracks; (2) whenever pronounced vertical cracks occur on other teeth than maxillary central incisors and canines or many horizontal cracks are observed, the bonding/debonding technique should be re-evaluated; (3) it seems advisable to notify parents/patients of marked cracks before orthodontic treatment is started, in order to avoid problems later when it is difficult or impossible to document their pretreatment existence.

Adhesives↗
PubMed1978

Clinical comparison of direct versus indirect bonding with different bracket types and adhesives.

A longitudinal clinical trial was made in forty-two children to compare some commonly used techniques for orthodontic bracket bonding. A particular study design (Figs. 1 and 5) allowed blind quadrantwise comparisons in the same patient of six different variables, including direct versus indirect bonding, adhesives of the filled diacrylate resin type with small versus large filler particles, and metal brackets with mesh-backed versus perforated bases. The same person bonded all brackets within one week and performed the orthodontic treatment by a friction-free edgewise light-wire technique. Efforts were made to minimize gingival irritation by using eccentrically placed brackets on small bases, by careful trimming of excess adhesives flash around the bases, and by directing much emphasis on oral hygiene measures. The plaque situation around the brackets and along the gingival margins and the gingival condition were assessed according to the criteria of the plaque and gingival index systems by a dental hygienist at each monthly visit during a test period of 6 months. The study demonstrated that both direct and indirect bonding with the different adhesives and bracket types could give clinically satisfactory results. Still, there were statistically significant differences in plaque retention, gingival inflammation, and bond strength. The bonding adhesive with small filler particles was more hygienic than and about as strong as two adhesives with larger, coarser filler particles. The mesh-backed brackets retained less plaque and gave stronger bonds than the brackets with perforated pads. Advantages of direct bonding over the indirect procedure were that (1) the bracket bases were fitted closer to the tooth surface (which improved bond strength), (2) it was easier to work clean and to remove excess adhesive flash around the bracket bases (to help prevent gingival inflammation and decalcification and facilitate debonding), and (3) the bonding adhesive constantly filled out the entire contact surface of the brackets (thus avoiding artificial undercuts and deficiency areas which are prone to promote decalcification). A number of other clinical observations were also discussed.

Acid Etching, Dental↗
PubMed1978

Improving orthodontic results in cases with maxillary incisors missing.

This article has aimed at providing information on how to improve clinical orthodontic results in cases in which maxillary central and lateral incisors are missing. Different sections deal with (1) treatment approach and mechanics, (2) details in finishing, (3) modifications of clinical tooth crowns by special procedures (grinding, composite "corners," gingivectomy), (4) functional considerations and root resorption, and (5) retention.

Bicuspid↗