Björn U. Zachrisson

A posttreatment evaluation of direct bonding in orthodontics.

A long-term evaluation was made of results achieved in direct bonding of metal attachments with a chemically polymerized composite material. A total of 705 attachments were bonded to different teeth, including premolars and molars, in forty-six children. Slim bracket bases, small quantities of adhesive paste, and trimming of the excess material were used to improve esthetics and to benefit in respect of gingival condition. The same person bonded all brackets and performed the orthodontic treatment by a friction-free edgewise light-wire technique. Mean treatment time was 17 months. The clinical appearance before, during, and after treatment is shown in Figs. 3 to 5. The failure rates for the whole treatment period were 4 to 10 per cent for central and lateral incisors, canines, and first premolars in both dental arches. The second premolars, which were often in various stages of eruption at the time of bonding, and the molars had higher failure rates (Table I). An evident individual variation was noted, as a few children had a high number of loose brackets. Clinical and scanning electron microscopic studies of tooth surfaces following removal of the brackets demonstrated normal surface appearance when plain-cut tungsten carbide burs rotated at low speed were used to remove remnants of adhesive that could not easily be scraped off. Precoating etched enamel with sealant, in combination with daily fluoride mouth rinses and good oral hygiene, virtually eliminated the caries problem, but regular inspection for interproximal cavities was needed. There were no signs of enamel damage or discoloration for periods of up to 12 months subsequent to bracket removal. Further details of the technical operative procedure, failure analysis, bracket type and design, gingival health, and other aspects of direct bonding were also discussed.

Periodontal condition in orthodontically treated and untreated individuals. I. Loss of attachment, gingival pocket depth and clinical crown height.

Abstract No Abstract Available. From the Department of Orthodontics and Pedodontics and the Dental Institute of Experimental Research, Dental Faculty, University of Oslo, Oslo, Norway.

Periodontal condition in orthodontically treated and untreated individuals. II. Alveolar bone loss: radiographic findings.

Abstract No Abstract Available. From the Department of Orthodontics and the Dental Institute of Experimental Research, Dental Faculty, University of Oslo, Oslo, Norway.

Clinical experience with direct-bonded orthodontic retainers

The experience obtained in clinical evaluation of forty-three direct-bonded mandibular canine-to-canine retainers after a minimum observation period of 1 year (range, 1 to 2.5 years) is summarized. Results indicate that the bonded retainer has all the advantages of a fixed soldered retainer, in addition to being invisible. Patient acceptance was excellent, and the failure rate in terms of loose retainers was low. Also, for a number of other retention problems, direct bonding with different types of lingual wire seems to open up a range of promising new possibilities.

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.

Surface preparation for orthodontic bonding to porcelain

This study evaluated the effect of various porcelain surface treatments on the tensile strength of orthodontic brackets bonded to a feldspathic metal ceramic porcelain. The porcelain was fused to flat gold alloy tabs and divided into six groups that were subjected to sandblasting, silane application, intermediate resin, or etchants (9.6% hydrofluoric acid or 4% APF gels). Two brackets were bonded onto each porcelain/metal tab (n=60) with Bis-GMA resin (Concise, 3M Corp., St. Paul, Minn.) or 4-META resin (MCP-bond, Sun Medical Co. Ltd., Tokyo, Japan). The samples were stored in 37 degrees C water, thermocycled 1000 times from 5 degrees C to 55 degrees C and tested in tension. Alignment and uniform loading during testing were secured by engaging a hook in a circular ring soldered onto the bracket slot before bonding. Similar control brackets (n=12) were bonded with Concise to extracted caries-free mandibular incisors. Bond failure sites were classified according to a modified Adhesive Remnant Index (ARI) system. Silane application to the sandblasted porcelain surface significantly increased the bond strengths according to analysis of variance and Duncans multiple range test. The quality of the bonds was further enhanced by the addition of the intermediate resin. Etching the porcelain with 9.6% hydrofluoric acid provided similar bond strengths, but the 4% APF gel was less effective. The MCP-bond was not significantly better than Concise in bond strength to sandblasted porcelain. Several difficulties associated with the clinical interpretation of laboratory data on bonding to dental porcelains are discussed, and clinical trials are necessary for final evidence of efficacy.

Fluoride application procedures in orthodontic practice, current concepts.

A survey is given of present knowledge of different methods of fluoride administration with emphasis on practical measures of proved value for orthodontic patients. The review covers different F administration procedures by dental personnel and self-application and includes the use of prophylaxis pastes, topical solutions, gels, mouth rinses, dentifrices, tablets, cements, coatings, varnishes, etc. Some recommendations are given as to optimal programs in orthodontic practice based upon evaluations of clinical effectiveness, safety and ease of application. Some caries reduction has been obtained from professional application of F prophylaxis pastes, but F pastes cannot replace topical F application. Treatment with F gels or solutions preceded by thorough cleaning and drying of the teeth is advocated before the placement of appliances and at recementations. Because F solutions are tedious to apply, and not more effective than F gels, the latter are preferable. APF gel application is suited in conjunction with impression taking. Daily self-application of SnF2 gels undoubtedly is effective in reducing caries in orthodontic patients. However, daily NaF or APF mouth rinses may have the dual effect of caries inhibition and stimulating hygiene interest and are more thoroughly tested. In addition to the other forms of F administration, a F dentifrice should be used regularly. Daily F application is appropriate also for orthodontic patients in fluoridated areas. In vitro studies with F cements indicate a great F uptake by the enamel, but controlled, long-term clinical studies are lacking. Also the final judgment of a number of new coating techniques and F varnishes must await further clinical testing, although a beneficial effect of F sealing in orthodontic patients is substantiated. In conclusion, APF gel application before insertion of appliances and at regular recementations plus daily rinsing with dilute NaF or APF solutions throughout the periods of treatment and retention plus the regular use of a F dentifrice is recommended as a routine procedure for all orthodontic patients.

Improving orthodontic bonding to silver amalgam.

Flat rectangular tabs (n = 84) prepared from lathe-cut amalgam (ANA 2000) were subjected to aluminum oxide sandblasting or roughening with a diamond bur. Mandibular incisor edgewise brackets were bonded to these tabs using: Concise (Bis-GMA resin); one of three metal-bonding adhesives, viz., Superbond C&B (4-META resin), Panavia Ex (10-MDP Bis-GMA resin) or Geristore (composite base); and Concise after application of the intermediate resins All-Bond 2 Primers A+B, or the Scotch-Bond Multi-Purpose (SBMP) system. All specimens were stored in water at 37 degrees C for 24 hours before tensile bond strength testing. Alignment and uniform loading during testing were secured by engaging a hook in a circular ring soldered onto the bracket slot before bonding. Similar control brackets (n = 12) were bonded with Concise to extracted caries-free mandibular incisors. Bond failure sites were classified by a modified ARI system. Mean tensile bond strengths in the experimental group ranged from 3.4 to 6.4 MPa--significantly weaker than the control sample (13.2 MPa). Bond failure generally occurred at the amalgam/adhesive interface. Superbond C&B created the strongest bonds to amalgam; according to ANOVA and Duncans Multiple-Range test, they were significantly stronger than the bonds with Panavia Ex and Concise, with Geristore in between. However, the bond strength of Concise to sandblasted amalgam was comparable to the Superbond C&B bonds when coupled with an intermediate application of All-Bond 2 Primers A+B. The SBMP, on the other hand, was less effective.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjustment of clinical crown height by gingivectomy following orthodontic space closure.

Abstract No Abstract Available. From the Department of Orthodontics, University of Oslo, Oslo, Norway.

Improving orthodontic bonding to gold alloy

Flat tabs of cast gold alloy (n = 156) were subjected to either of three surface treatments: (1) roughening with diamond bur, (2) aluminum oxide sandblasting, and (3) sandblasting plus tin electroplating. Mandibular incisor edgewise brackets were bonded with Concise (BIS-GMA resin) (Unitek, Monrovia, Calif.) or Superbond C&B (4-META metal bonding resin) (Sun Medical Co. Ltd., Kyoto, Japan), or with Concise after application of an intermediate resin. All-Bond 2 Primers A and B (Bisco Dental Products, Itasca, Ill.), or B alone. All specimens were stored in water at 37 degrees C for 24 hours, and 60 were then thermocycled 1,000 times from 5 degrees C to 55 degrees C and back. The tensile bond strength testing was performed in a Lloyd 1,000R machine (Fareham, Hants, England). Alignment and uniform loading during testing were secured by engaging a hook in a circular ring soldered onto the bracket slot before bonding. Similar control brackets (n = 24) were bonded with Concise to extracted human premolars and lower incisors according to a routine procedure. Bond failure sites were classified by a modified ARI system. The results showed that sandblasting produced significantly stronger bonds to gold alloy than roughening with diamond bur. Superbond C&B provided significantly stronger bonds to gold alloy than Concise. There were generally insignificant differences in bond strengths between the water stored and the thermocycled specimens. Bond failures of Concise to sandblasted plus tin-plated gold alloy invariably occurred at the gold/adhesive interface, whereas those of Superbond C&B occurred within the adhesive or in the adhesive/bracket interface.(ABSTRACT TRUNCATED AT 250 WORDS)