Faustin N. Weber

Shear strength of orthodontic direct-bonding adhesives☆

A total of 210 double-width stainless steel edgewise brackets with retentive lip bases were bonded to bovine incisors with seven commercially available direct-bonding materials. Ten samples for each of the seven direct-bonding materials were tested for shear strength using the Instron Universal Testing Instrument. The samples were tested after 1 day, 1 month, and 3 months of immersion in 30 per cent physiologic saline solution. The mean shear strength of each direct-bonding material at each time interval was compared statistically to the mean shear strength of each of the materials at each time interval with a matched 1 test. The same test was used to determine whether there had been a significant change in mean shear strength from start to finish of testing for each material. One product showed a significantly better mean shear strength than any other material at each test interval. The remaining materials were grouped in middle or low ranges, depending upon their final mean shear strengths and degrees of nonsignificance when compared to each other.

Dimensional stability of irreversible hydrocolloid impression material

Abstract A total of 200 alginate impressions were made from a standard metal model that was grooved at four points to provide precise sites for making buccolingual and mesiodistal measurements to determine dimensional stability. Each of four commercially available alginate impression materials was subjected to five different storage methods prior to pouring in an effort to determine which impression material and storage method produced the most accurate casts. Ten casts were produced from each material-method combination. Means and standard deviations were computed from the buccolingual and mesiodistal measurements of each group of ten casts. These measurements were then compared to the same measurements of the standard model. An analysis of variance and the Duncan Multirange Test were used to determine total error, taking into account each alginate material, each storage method, and the interaction between the two. The immediate-pour technique produced the most accurate casts, and Product B was the material of choice with this method. Product C and Product D were more accurate over-all than Product A and Product B with all storage methods. The accuracy of Product B diminished most rapidly when this material was subjected to any method of storage. The 24-hour storage in a wet paper towel with refrigeration was the least desirable method of storage.

Preventing enamel decalcification during orthodontic treatment

One hundred thirty-two extracted premolar teeth were selected and divided into four equal groups. The first group of thirty-three teeth received a topical application of acidulated phosphate fluoride; the second group, a topical application of stannous fluoride; the third group, an application of a polymeric adhesive coating; the fourth group was left untreated to serve as a control. On each tooth a loosely fitted orthodontic band was cemented to place. After cementation, the band was broken to simulate a loose orthodontic band in vivo. The four groups of teeth were simultaneously immersed in a decalcifying gelatin and were left undisturbed for 11 weeks. The teeth were then removed and a record was made of the decalcification produced. A chi-square test was used to compare the teeth in each group to those in every other group. Compared to a control group of teeth, those teeth treated with polymeric adhesive coating, acidulated phosphate fluoride, or stannous fluoride produced a statistically significant reduction in decalcification of the tooth surfaces beneath loose orthodontic bands. For a one-application technique, the polymeric adhesive coating provided more protection against decalcification of teeth under loose orthondontic bands than did either acidulated phosphate fluoride or stannous flouride.

Clinical investigations related to use of the Begg technique at the University of Tennessee

Abstract Some of the clinical phenomena that have been observed when patients are treated with the Begg light wire differential force technique are herein recorded. The investigations reported were carried out by graduate students using the clinical records of patients treated by the Begg technique in the orthodontic clinic of the University of Tennessee, supplemented by records from the files of several orthodontists. We hope to repeat and amplify the extent of some of these studies when our use of the Begg technique provides us with a larger sample than was available when the investigations were first conducted.

Preparations to prevent enamel decalcification during orthodontic treatment compared: An in vitro study

Abstract One hundred twenty extracted premolar teeth were divided into five groups of equal size. One group of teeth was treated with a copal resin varnish, another was treated with an unfilled bis GMA resin; the third was treated with a polymeric adhesive coating; the fourth received a protective application of an ultraviolet-light-activated bis GMA resin; and the fifth was left untreated. Each tooth then had an orthodontic band loosely fitted and cemented into place, after which the cement seal was broken to simulate a loose orthodontic band in vivo. Next, all teeth were thermocycled and immediately immersed in a decalcifying gelatin. At the end of 7 weeks, one third of the teeth in each group were removed and examined. At 14 weeks, the second third of the teeth in each group were removed and evaluated. The final third of the teeth in each group were evaluated at 21 weeks. At each time interval the teeth were studied to determine whether any decalcification had taken place. The chi-square test was used to note differences among the five groups of teeth; differences between groups of teeth treated with acid-etch products and the nonetched group; and among the acid-etched groups themselves. For a one-application technique, the ultraviolet-light-activated bis GMA resin used in this study provided more protection against in vitro decalcification of teeth under loose orthodontic bands than did any other product in the study.

Corrective measures during the mixed dentition

Abstract In the last quarter of a century, the attitude of orthodontists regarding the advisability of treating certain types of malocclusion has changed twice. From the viewpoint most men held in the 1930s, that almost all malocclusions were indications for treatment in the mixed dentition, the consensus changed to such a degree that only a few types of cases were deemed suitable for mixed dentition treatment. Now the pendulum seems to be swinging back again! Tweed 27 says that more than 50 per cent of his cases are taken from this mixed dentition group and he expresses the wish that it could be 100 per cent. No small amount of the shift back toward more treatment in the mixed dentition period must be attributed to the rediscovery and use of extraoral anchorage. A list of mixed dentition treatment indications, some involving mechanotherapy, others not, has been given and the list discussed briefly. Perhaps orthodontists in the near future will rarely, if ever again, recommend, as orthodontists did in the recent past, that no treatment be started before the patient is 12 years old. Indeed, the mixed dentition age bids fair to become the “golden age” in clinical orthodontic therapy.

The treatment of extraction cases using a modified Johnson twin arch wire technique

Abstract A treatment technique for the orthodontic management of extraction cases, using a modified Johnson twin arch wire, has been described. The areas in which this technique differs from the conventional twin arch wire technique are (1) the use of sectional appliances in the distal movement of canines, (2) the use of palatal anchorage accompanying the sectional arch wires, (3) the use of twin-tie attachments and round wires in the mandibular dental arch, and (4) the utilization of extraoral anchorage to augment the intraoral anchorage.

Orthodontic education for the nonorthodontist: Why, where, and how

Abstract Malocclusion is found in so many children that orthodontists cannot possibly treat all who need orthodontic care. Treatment is ruled out for many children, not only because of the shortage of qualified orthodontic specialists but also because of their geographic distribution and the relatively high cost of orthodontic treatment. Much malocclusion can be prevented or intercepted by the application of effective and usually simple measures. A list of indications is presented. Prophylactic or interceptive orthodontic techniques can be learned and applied by pedodontists and general practitioners of dentistry. The orthodontists obligation to serve as teacher and consultant to his nonorthodontist colleagues by being a clinician on local and state dental programs is emphasized. If he assumes this obligation, fewer patients will be the victims of orthodontic treatment that is improperly planned by commercial laboratories and ineptly executed by inexperienced operators.

Orthodontics in retrospect and prospect

Abstract The developments that have already taken place, as well as those that are just over the horizon, in the fields of dental education, research, and practice have a mind-boggling effect when we try to evaluate their influences on our professional lives and the people we serve. Having an increased number of patients to care for will compel us to completely overhaul the dental care delivery system from its present form. As Zapp 48 observed, we shall have to reorganize our profession to deliver more care for more people, instead of designing a practice that is more comfortable to our own personal style. Changes in dental education may have to be even more dramatic and dental educators no less resourceful than those in dental practice to furnish professional and subprofessional personnel adequately trained and in sufficient numbers to man and efficiently operate dental health care facilities of the future. The contributions of dental research will continue to make the efforts of both the dental educator and the dental practitioner more effective. These coming events, which have already cast their shadows before them, do present a challenge, a challenge “to the professions capacity for leadership and wisdom, for foresight and innovation, for courage to move in new directions, for removal of the restraining bonds of fear which forbid all change and canonize the status quo ….” 42 Sociologic, economic, and political events have already done some violence to the image of orthodontic practice as we have known it in the past two decades, but the metamorphosis that has been wrought will pale to insignificance when measured against what we may expect in the coming two decades.

HOW CAN WE EDUCATE MORE ORTHODONTISTS?THE REGIONAL CENTER FOR ADVANCED ORTHODONTIC EDUCATION.

Abstract At present neither the need nor the demand for orthodontic services is being met. More orthodontists must be trained in the immediate future to care for the children who are now being denied essential orthodontic treatment, or our problem will become much more serious than it already is. The university-sponsored programs are supplying only about 250 new orthodontists each year; the preceptorship programs of instruction are supplying an additional twenty-five, but this latter source of trainees has a limited existence. The universities are unwilling or unable to establish new graduate programs in orthodontics or to enlarge those already operating either because they lack the staff, the physical facilities, or the funds or because their administrative officers lack interest in the programs. In this article a method has been suggested of overcoming, at least in part, these deficiencies in staff, physical facilities, money, and administrative interest through the establishment of a regional center for advanced orthodontic education. An estimate of the cost of erecting a center for advanced orthodontic education for sixty students, as well as the estimated income and expense of operating the center, is included.