Effects of unilateral molar distalization with a modified pendulum appliance

Comparison of the Pendulum appliance and the Jones Jig: A prospective comparative study

Objective:

To compare two molar distalization devices, the Pendulum appliance (PA) and the Jones Jig (JJ) in dental Class II patients.

Materials and Methods:

Pretreatment and postdistalization lateral cephalograms and study models of 20 subjects (6 males, 14 females) Class II malocclusion subjects were examined. PA and JJ group both consisted of 10 patients each with a mean pretreatment age of 12 years 1 month for females and 12 years 5 months for males. The PA and the JJ appliance were activated once in a month until Class II molar relationship was corrected to a super Class I molar relationship in both groups. Initial and final measurements and treatment changes were compared by means of Paired t-test.

Results:

Maxillary first molar distalized an average of 3.85 mm in the PA and 2.75 mm in the JJ between T1 and T2; rate of molar distalization was 1.59 mm/month for PA, and the JJ appliance averaged 0.88 mm/month, distal molar tipping was greater in PA (6.2°) than in the JJ (3.9°). Average mesial movement of the premolars was 2.2 mm with PA and JJ both. JJ showed a greater rotation of first molars after distalization as compared to PA. The increase in vertical facial height was also greater for JJ as compared to PA.

Conclusions:

Both the appliances were effective in molar distalization with PA requiring less distalization time (16 days less than JJ). Some adverse effects were noted with both which one should strive to control.

[Intramaxillary devices of molar distalization on fixed appliance and with aligners]

INTRODUCTION

Class II malocclusion is a dysmorphosis that can result from different skeletal and/or alveolar components of maxillary and/or mandibular origin. In dental class II cases due to mesial drift of the maxillary molars, it is sometimes interesting to retract the maxillary molars, in order to avoid in certain situations extractions of premolars. To this end, several devices have been described in the literature. The most recent intraoral devices allow a more controlled correction, and no longer require cooperation from the patient. In addition, in a number of cases of distalization, aligners now offer a useful therapeutic option since they are both esthetic and easy-to-use.

MATERIALS AND METHODS

In this study, we carried out a review of the various studies in the literature describing intra-oral distalization of the maxillary molars in the multi-bracket technique as well as using aligners, with a clinical illustration of a Class II case treated by aligners.

Orthodontic treatment for distalising upper first molars in children and adolescents

BACKGROUND

When orthodontic treatment is provided with fixed appliances, it is sometimes necessary to move the upper molar teeth backwards (distalise) to create space or help to overcome anchorage requirements. This can be achieved with the use of extraoral or intraoral appliances. The most common appliance is extraoral headgear, which requires considerable patient co-operation. Further, reports of serious injuries have been published. Intraoral appliances have been developed to overcome such shortcomings. The comparative effects of extraoral and intraoral appliances have not been fully evaluated.

OBJECTIVES

To assess the effects of orthodontic treatment for distalising upper first molars in children and adolescents.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 10 December 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 11), MEDLINE via OVID (1946 to 10 December 2012) and EMBASE via OVID (1980 to 10 December 2012). No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

Randomised clinical trials involving the use of removable or fixed orthodontic appliances intended to distalise upper first molars in children and adolescents.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by The Cochrane Collaboration. We performed data extraction and assessment of the risk of bias independently and in duplicate. We contacted authors to clarify the inclusion criteria of the studies.

MAIN RESULTS

Ten studies, reporting data from 354 participants, were included in this review, the majority of which were carried out in a university dental hospital setting. The studies were published between 2005 and 2011 and were conducted in Europe and in Brazil. The age range of participants was from nine to 15 years, with an even distribution of males and females in seven of the studies, and a slight predominance of female patients in three of the studies. The quality of the studies was generally poor; seven studies were at an overall high risk of bias, three studies were at an unclear risk of bias, and we judged no study to be at low risk of bias.We carried out random-effects meta-analyses as appropriate for the primary clinical outcomes of movement of upper first molars (mm), and loss of anterior anchorage, where there were sufficient data reported in the primary studies. Four studies, involving 159 participants, compared a distalising appliance to an untreated control. Meta-analyses were not undertaken for all primary outcomes due to incomplete reporting of all summary statistics, expected outcomes, and differences between the types of appliances. The degree and direction of molar movement and loss of anterior anchorage varied with the type of appliance. Four studies, involving 150 participants, compared a distalising appliance versus headgear. The mean molar movement for intraoral distalising appliances was -2.20 mm and -1.04 mm for headgear. There was a statistically significant difference in mean distal molar movement (mean difference (MD) -1.45 mm; 95% confidence interval (CI) -2.74 to -0.15) favouring intraoral appliances compared to headgear (four studies, high or unclear risk of bias, 150 participants analysed). However, a statistically significant difference in mean mesial upper incisor movement (MD 1.82 mm; 95% CI 1.39 to 2.24) and overjet (fixed-effect: MD 1.64 mm; 95% CI 1.26 to 2.02; two studies, unclear risk of bias, 70 participants analysed) favoured headgear, i.e. there was less loss of anterior anchorage with headgear. We reported direct comparisons of intraoral appliances narratively due to the variation in interventions (three studies, high or unclear risk of bias, 93 participants randomised). All appliances were reported to provide some degree of distal movement, and loss of anterior anchorage varied with the type of appliance.No included studies reported on the incidence of adverse effects (harm, injury), number of attendances or rate of non-compliance.

AUTHORS' CONCLUSIONS

It is suggested that intraoral appliances are more effective than headgear in distalising upper first molars. However, this effect is counteracted by loss of anterior anchorage, which was not found to occur with headgear when compared with intraoral distalising appliance in a small number of studies. The number of trials assessing the effects of orthodontic treatment for distilisation is low, and the current evidence is of low or very low quality.

Effects of the zygoma anchorage system on canine retraction

The aim of this study was to compare the effects of the Gjessing (PG) retraction spring used with and without the zygoma anchorage system (ZAS) on canine retraction. Thirty patients, with an Angle Class I or Class II malocclusion, whose upper first premolars were scheduled for extraction, were divided into two equal groups. Group 1 comprised maximum anchorage cases (nine females and six males with a mean age of 16 years 8 months) in which the ZAS was used to improve posterior anchorage and the PG retraction springs for canine retraction. Moderate anchorage cases (10 females and 5 males with a mean age of 15 years 5 month) were included in group 2 and canine retraction was achieved using only PG retraction springs. Study models and lateral cephalometric radiographs obtained at the initial and final stages of canine retraction were used for comparison of the groups to determine the effects of zygoma anchorage on canine retraction. All measurements were evaluated statistically using a Student's t-test, 2 × 2 repeated measures analysis of variance, Bonferroni-adjusted t-test, and Mann-Whitney U and Wilcoxon tests according to the normality of the distribution of the variables. Mesial crown movement of the molars was 0.63 mm (P < 0.05) in group 1 and 1.50 mm (P < 0.001) in group 2. There was a statistically significant difference (P < 0.05) between the groups. No significant difference was observed between the groups for the rate of canine retraction or sagittal and vertical movement of the canines. The ZAS is a reliable and successful anchorage reinforcement method for canine retraction in extraction cases.

Molar distalization with a pendulum appliance K-loop combination

SUMMARY

The aim of this study was to evaluate the dentoalveolar effects of a pendulum appliance supported buccally by a K-loop, and to compare these with a cervical headgear (CHG) group. The records of 30 patients with skeletal Class I and dental Class II malocclusions were divided in to two groups: Patients in group 1 (seven females and eight males; mean age, 15.0 +/- 3.4 years) were treated with a pendulum appliance supported with a K-loop buccally, while in group 2 (10 females and 5 males; mean age, 14.2 +/- 2.9 years), the patients were treated with CHG. Standardized lateral cephalograms and study models were taken at the beginning of treatment (T0) and at the end of distal molar movement (T1). T0-T1 changes within the groups were analysed with a paired t-test, and between the groups with a t-test. The mean amount of distalization was 4.53 +/- 1.46 mm in group 1 and 2.23 +/- 1.68 mm in group 2. The mean amount of distal tipping for group 1 was 5.13 +/- 4.90 degrees; the mean amount of mesial tipping for group 2 was 0.80 +/- 2.27 degrees. Intrusion and mesiobuccal rotation of the maxillary molars were achieved in both groups. In group 1, the amount of labial protrusion and tipping of the maxillary incisors was not statistically significant. In group 2, palatoversion and retrusion of the maxillary incisors was statistically significant (P < 0.01 and P < 0.001, respectively). The two major disadvantages of intraoral appliances, which are distal tipping of molars and loss of anchorage at the anterior teeth, were significantly decreased with the use of a pendulum appliance K-loop combination.