Dentoskeletal effects of class II malocclusion treatment with the modified Twin Block appliance

Abstract

BackgroundThe purpose of this study was to prospectively assess the dentoskeletal effect of a modified Twin Block appliance for treatment of class II malocclusions.Material and MethodsLateral cephalograms of 25 Class II malocclusion patients were compared to evaluate skeletal, dentoalveolar and soft tissue changes pre- and post-treatment with a modified Twin Block appliance. A total of 33 angular and linear variables were used for analysis. The differences were calculated at the start and end of treatment. The paired T test was performed to compare the cephalometric measurements before and after treatment.ResultsCompared the pre- and post- treatment measurements, there was a significant increase in SNB (P<0.001), CO-Gn (P<0.001), ANS-Me (P=0.001), Mandibular base (P<0.001), Lower 1 to NB (°) (P=0.004), Lower 1 to NB (mm) (P<0.001), and Z-angle (P=0.001) following functional therapy with modified Twin Block appliance. On the other hand, a significant decrease was observed in ANB (P<0.001), NA-Pog (P<0.001), overjet (P<0.001), and overbite (P=0.007), Upper 1 to palatal plane (P=0.007), UL-E-line (P<0.001), LL-E-line (P=0.001), and H-angle (P=0.002) after treatment with modified Twin Block appliance.ConclusionsThe modified Twin-Block improves facial esthetics in Class II malocclusion by a combination of changes in skeletal as well as dentoalveolar structures. The increase of mandibular unit length was observed to be due to a true mandibular growth not just a repositioning of the mandible. The modified appliance, however, did not show any superior effects in terms of less dental compensation compared to the conventional Twin–Block appliance. Key words:Dentoskeletal effect, Modified Twin Block, Class II malocclusion.

Volumetric Evaluation of Pharyngeal Airway after Functional Therapy

“…Class II sagittal relation improved significantly due to the forward mandibular displacement and increase in the effective mandibular length (Co-Gn). Similar to our results, several clinical studies investigating changes caused by the TB have demonstrated its effectiveness in increasing mandibular growth [ 15 – 21 , 23 , 24 , 28 , 29 ]. Although a mild decrease was found in SNA angle, midfacial length (Co-A) did not change revealing that TB has only restraining effect on the maxillary growth.…”

“…Its popularity depends on high patient cooperation and its ability to produce rapid correction of sagittal discrepancy due to fulltime wear. In some previous studies, the effects of TB on the skeletal and dentoalveolar structures [15][16][17][18][19] and temporomandibular joint [20] were evaluated. Additionally, Zhang et al [21] and Shete and Bhad [22] reported that TB appliance may improve the obstructive sleep apnea (OSA) symptoms in patients with mandibular retrognathia.…”

Dentoskeletal effects of Twin Block appliance in patients with Class II malocclusion

“…A significant decrease in overjet (5.72 mm) and overbite were observed at the end of treatment in the Twin Block group compared with untreated Class II controls. This finding is in accordance with studies by Clark [10], Illing et al [16], O'Brien et al [24], Sharma et al [25], Trenouth [29], Khoja et al [32] and Ajami et al [34].…”

“…The mandibular molars in the Twin-block subjects showed extrusion (2.38 mm) and mesial movement (4.5 mm) significantly greater than in the control group (0.5 mm) which is similar to studies by Mills and McCulloch [26], Lund and Sandler [28] and Pattanaik S et al [34]. The effect on mandibular incisors is critical and variable in different studies.…”

“…These findings were similar to previous studies by Mills and McCulloch [23] who reported a 6.5 mm increase in effective mandibular length, Toth and McNamara [27] reported a 3.0 mm increase in mandibular growth. In addition, Giuntini et al [31], Khoja et al [32], Pattanaik et al [33,] and Ajami et al [34] reported similar results of increased mandibular length.…”