Class II correction-reducing patient compliance: a review of the available techniques.

The correction of Class II malocclusions has been hampered by the use of appliances which require the patient to co-operate with headgear, elastics, or the wearing of a removable appliance. 'Non-compliance therapy' involves the use of appliances which minimize the need for such co-operation and attempt to maximize the predictability of results. This article reviews and describes the types of appliances used, and their mode of action-based on the current available research.

The effects of sandblasting on the bond strength of molar attachments--an in vitro study.

This study evaluated the effect of sandblasting foil mesh molar tube bases on the shear bond strength obtained when bonding to first molar teeth. Fifty-two recently extracted first molar teeth were etched with 35 per cent phosphoric acid gel for 30 seconds. Twenty-six sandblasted 'A' Company molar tube attachments and 26 non-sandblasted attachments were then bonded to the teeth using Phase II orthodontic bonding resin. After storage in water for 24 hours at 37 degrees C, the specimens were debonded in a direction parallel to the buccal surface. Survival analysis using the Weibull function revealed that for a 90 per cent probability of survival, the predicted bond strengths for sandblasted and non-sandblasted bases were 1.76 and 1.66 MPa, respectively. For larger shear stresses, the probabilities of bond survival with sandblasted molar tubes were greater than with non-sandblasted molar tubes although the differences were small, which may be explained by the large proportion of bond failures which occurred at the resin to enamel interface in both groups. It was concluded that sandblasting foil mesh bases is likely to provide only a minimal improvement in clinical performance when bonding to molar teeth.

The ectopic maxillary canine: a review.

This article reviews the aetiology and management of the ectopic maxillary canine. Much controversy surrounds the causes of canine palatal ectopia. The recent evidence surrounding the genetic and guidance theories are examined. The management options are detailed and the indications for each treatment modality based on the available scientific evidence are presented. Finally, the untoward sequelae of canine ectopia are discussed.

Outcome prediction of the anterior open bite. Comparison of computer and clinician analysis of cephalograms.

Anterior open bite (AOB) may be expected to close spontaneously in approximately 50% of Caucasian patients. Computer-derived discriminant analysis of a single cephalometric radiograph has been shown to predict closure or non-closure in 88% of patients at the pre-puberal stage, in 74% at the puberal stage, and in 94% at the post-puberal stage. In this study, the predictive capacity of the computer analysis was tested against predictions made by groups of clinicians in Belfast and Toronto. The computer analysis was carried out on the first cephalometric radiographs of a new sample of 34 open bite cases collected serially and recorded over a minimum of 2 years. Thus, the spontaneous outcome was known to the authors. The first radiographs were shown to 20 clinicians in Belfast and 22 in Toronto who were asked to predict the spontaneous outcome. The computerised discriminant analysis made correct predictions in 85% and the clinicians in 64% of the sample. There were no significant differences between the predictions of clinicians in Belfast and Toronto, but computer prediction was more accurate than all grades of clinician. The predictions of qualified orthodontists were generally more accurate than prequalified orthodontists which were more accurate than those of undergraduate dental students but the differences did not rise to the level of statistical significance. For patients at the puberal stage the predictive capacity of qualified orthodontists was less than orthodontists in training. Computer prediction of the spontaneous outcome in open bite improves clinical diagnosis.

Class III malocclusions: the choice between orthodontics or surgery.

In summary, orthodontic treatment tends to be successful if there is:- Low Maxillomandibular planes angle Little Compensation Small reverse overjet Symmetric growth pattern Failure occurs due to:- Unfavourable growth pattern High degree of compensation Large negative overjet The treatment of the Class III malocclusions is considered. The extent to which Class III cases can be treated with Orthopaedic appliances is outlined and discussed. The positive and negative factors influencing the decision for orthodontic or surgical treatment are considered and finally stability is examined.

Class III malocclusions: the choice between orthodontics or surgery.

In summary, orthodontic treatment tends to be successful if there is:- Low Maxillomandibular planes angle Little compensation Small reverse overjet Symmetric growth pattern Failure occurs due to:- Unfavourable growth pattern High degree of compensation Large negative overjet The treatment of the Class III malocclusions is considered. The extent to which Class III cases can be treated with Orthopaedic appliances is outlined and discussed. The positive and negative factors influencing the decision for orthodontic or surgical treatment are considered and finally, stability is examined.

An in vitro evaluation of the tensile and shear strengths of four adhesives used in orthodontics.

The in vitro shear and tensile strength of four enamel adhesives was investigated. The materials examined were System 1+, Vitrebond, C & B Metabond and Panavia-Ex (original version). The mode of failure of each material was also investigated under a scanning electron microscope. Edgewise mesh-backed brackets were bonded to the buccal surface of extracted premolar teeth and forces applied with an Instron 1011 testing machine. Results indicated that Panavia-Ex (with sandblasted brackets) had the highest tensile strength when compared to the other materials (P < 0.01). Panavia-Ex had the highest shear strength when compared to C & B Metabond (P < 0.05) and to the other materials (P < 0.01). C & B Metabond had the highest shear and tensile strength of the other adhesives (P < 0.01). No significant differences were found for System 1+ when compared to Vitrebond for tensile strength, but System 1+ was stronger for shear strength (P < 0.01). Analysis of failure shows that 50% of the samples failed at the adhesive-enamel interface, 25% failed in a combined mode and the remaining 25% failed either adhesively to metal or cohesively.

The assessment of and treatment options for the buried maxillary canine.

Impaction of the upper permanent canine is almost as common as impaction of the third molar. The likelihood of being able to align one of these teeth with the rest of the dentition depends on a number of factors, and several treatment options are available.

Aetiology and treatment of anterior open bite.

AOB can be acquired or skeletal in nature. Treatment of skeletal open bites can be difficult, especially with fixed appliances. Magnetic biteblocks have recently gained popularity. Surgery may be necessary in the patient with a severe skeletal discrepancies and usually involves differential maxillary impaction.