Dental and skeletal changes in mild to moderate Class II malocclusions treated by either a Twin-block or Xbow appliance followed by full fixed orthodontic treatment.

OBJECTIVE: To compare the short-term skeletal and dental effects of two-phase orthodontic treatment including either a Twin-block or an XBow appliance. MATERIALS AND METHODS: This was a retrospective clinical trial of 50 consecutive Class II cases treated in a private practice with either a Twin-block (25) or XBow (25) appliance followed by full fixed orthodontic treatment. To factor out growth, an untreated Class II control group (25) was considered. RESULTS: A MANOVA of treatment/observation changes followed by univariate pairwise comparisons showed that the maxilla moved forward less in the treatment groups than in the control group. As for mandibular changes, the corpus length increase was larger in the Twin-block group by 3.9 mm. Dentally, mesial movement of mandibular molars was greater in both treatment groups. Although no distalization of maxillary molars was found in either treatment group, restriction of mesial movement of these teeth was seen in both treatment groups. Both treatment groups demonstrated increased mandibular incisor proclination with larger increases for the XBow group by 3.3°. The Wits value was decreased by 1.6 mm more in the Twin-block group. No sex-related differences were observed. CONCLUSIONS: Class II correction using an XBow or Twin-block followed by fixed appliances occurs through a relatively similar combination of dental and skeletal effects. An increase in mandibular incisor inclination for the XBow group and an increased corpus length for the Twin-block group were notable exceptions. No overall treatment length differences were seen.

Dental and skeletal changes in mild to moderate Class II malocclusions treated by either a Twin-block or Xbow appliance followed by full fixed orthodontic treatment.

OBJECTIVE: To compare the short-term skeletal and dental effects of two-phase orthodontic treatment including either a Twin-block or an XBow appliance. MATERIALS AND METHODS: This was a retrospective clinical trial of 50 consecutive Class II cases treated in a private practice with either a Twin-block (25) or XBow (25) appliance followed by full fixed orthodontic treatment. To factor out growth, an untreated Class II control group (25) was considered. RESULTS: A MANOVA of treatment/observation changes followed by univariate pairwise comparisons showed that the maxilla moved forward less in the treatment groups than in the control group. As for mandibular changes, the corpus length increase was larger in the Twin-block group by 3.9 mm. Dentally, mesial movement of mandibular molars was greater in both treatment groups. Although no distalization of maxillary molars was found in either treatment group, restriction of mesial movement of these teeth was seen in both treatment groups. Both treatment groups demonstrated increased mandibular incisor proclination with larger increases for the XBow group by 3.3°. The Wits value was decreased by 1.6 mm more in the Twin-block group. No sex-related differences were observed. CONCLUSIONS: Class II correction using an XBow or Twin-block followed by fixed appliances occurs through a relatively similar combination of dental and skeletal effects. An increase in mandibular incisor inclination for the XBow group and an increased corpus length for the Twin-block group were notable exceptions. No overall treatment length differences were seen.

Short-term treatment effects produced by the Twin-block appliance: a systematic review and meta-analysis.

OBJECTIVE: To evaluate dental, skeletal, and soft tissue effects during Twin-block treatment. METHODS: A systematic search of several electronic databases (Medline, PubMed, Embase, all EBM reviews, and Web of Science) was conducted until July 2013, as well as a limited grey-literature search (Google Scholar). Human cephalometric studies that used a Twin-block appliance in a non-extraction and non-surgical approach were selected. A comparable control group of untreated subjects was required. Two authors independently reviewed and extracted data from the selected studies. Risk of bias was assessed. The type of meta-analysis was selected based on heterogeneity. RESULTS: Ultimately 10 articles were included. Proclination of lower incisors, retroclination of upper incisors, distal movement of upper molars and/or mesial movement of lower molars, increase in mandibular length, and/or forward movement of the mandible were consistently reported. Clinically significant restraint of maxillary growth was not found. Although the mandibular body length is increased, the facial impact of it is reduced by the simultaneous increment of the face height. Changes of lower face height and occlusal plane inclination varied, suggesting that vertical dimension can be manipulated in patients who would benefit from lower molar extrusion. As for lip position, there is not enough evidence to suggest clear lip position changes. CONCLUSIONS: Changes associated with a Class II correction were identified. Most of the changes individually were of limited clinical significance, but when combined reached clinical importance. No long-term changes were available.

Frictional resistance in self-ligating orthodontic brackets and conventionally ligated brackets. A systematic review.

OBJECTIVE: To compare the amount of expressed frictional resistance between orthodontic self-ligating brackets and conventionally ligated brackets in vitro as reported in the literature. METHODS: Several electronic databases (Medline, PubMed, Embase, Cochrane Library, and Web of Science) were searched without limits. In vitro studies that addressed friction of self-ligating brackets compared with conventionally ligated brackets were selected and reviewed. In addition, a search was performed by going through the reference lists of the selected articles to identify any paper that could have been missed by the electronic searches. RESULTS: A total of 70 papers from the electronic database searches and 3 papers from the secondary search were initially obtained. After applying the selection criteria, only 19 papers were included in this review. A wide range of methods were applied. CONCLUSIONS: Compared with conventional brackets, self-ligating brackets produce lower friction when coupled with small round archwires in the absence of tipping and/or torque in an ideally aligned arch. Sufficient evidence was not found to claim that with large rectangular wires, in the presence of tipping and/or torque and in arches with considerable malocclusion, self-ligating brackets produce lower friction compared with conventional brackets.