Changes of epiglottis and hyoid bone position after orthodontic treatment with cast splint fixed functional appliances

Cephalometric evaluation of pharyngeal airway and tongue space following treatment with Herbst and AdvanSync appliances : A prospective randomized clinical trial

OBJECTIVES

To evaluate and compare pharyngeal airway and tongue space changes after treatment with fixed functional appliances-Herbst and AdvanSync™ (Ormco, Orange, CA, USA) appliances-in skeletal class II patients in pre- and posttreatment lateral cephalograms.

METHODS

For this randomized, controlled trial, 40 patients (21 male, 19 female) were divided into two groups-a Herbst group (mean age 12.6 ± 0.67 years) and an AdvanSync group (mean age 12.8 ± 0.66 years). Pre- and posttreatment (appliance therapy duration-8 months) lateral cephalograms were traced using a software program to evaluate pharyngeal airway and tongue space changes.

RESULTS

Nasopharyngeal airway, velopharyngeal airway, glossopharyngeal airway, and hypopharyngeal airway increased in the Herbst group by 2.12 mm (p ≤ 0.001), 2.33 mm (p ≤ 0.001), 2.40 mm (p ≤ 0.01), and 1.57 mm (p ≤ 0.05), while in the AdvanSync group the increases were 1.89 mm (p ≤ 0.001), 1.21 mm (p ≤ 0.001), 1.18 mm (p ≤ 0.001), and 1.53 mm (p ≤ 0.001), respectively. In the Herbst group, tongue length and height increases were 2.04 mm (p ≤ 0.01) and 3.74 mm (p ≤ 0.001), while the values in the AdvanSync group were 2.41 mm (p ≤ 0.05) and 2.69 mm (p ≤ 0.001). The change of the tongue tip from the lower occlusal plane was 0.69 mm (p ≤ 0.001) in the Herbst group and 0.77 mm (p ≤ 0.001) in the AdvanSync group. The velopharyngeal airway dimension was correlated positively with that of the retroglossal oropharyngeal airway, which in-turn positively correlated with the laryngopharyngeal airway which correlated well with the distance of the tongue tip from the lower occlusal plane.

CONCLUSIONS

The airway dimensions and tongue parameters increased significantly in both treatment groups in the present study. These changes were higher in the Herbst appliance than in the AdvanSync group, except for the distance of the tongue tip from the lower occlusal plane. A significant difference between the pharyngeal airways was found only for the retropalatal oropharyngeal airway.

Effect of the Mandibular Repositioning Appliance (MARA) on Posterior Airway Space (PAS)

Aim of the study was to show the effect of skeletal Class II treatment with the mandibular anterior repositioning appliance (MARA) on the sagittal posterior airway space (PAS) diameter. A total of 53 patients were selected retrospectively: 26 male patients (median 13 years, age span 10–19 years) and 27 female patients (median 14 years, age span 11–47 years). All patients had lateral cephalograms taken at T1 (before MARA treatment) and at T2 (after MARA treatment). Average treatment took 13.1 ± 7.5 months (Group 1) and 10.5 ± 4.5 months (Group 2), respectively. The following PAS parameters were obtained at T1 and T2: TI (Tangent Point 1), Me/Gn (menton/gnathion), DW (dorsal wall). Additionally, Björk‘s sum angle, SNA, SNB and ANB were determined. The male patients showed a higher increase in the anteroposterior diameter of the PAS (+27.5%) compared to female patients (+11.6%). Male participants had a significantly higher PAS (p = 0.006) than female participants (p = 0.09). Although not significantly, Björk‘s sum angle decreased in both groups. In general, compared to female patients, male patients showed a greater decrease between T1 and T2. SNA and SNB exhibited varied behavior between T1 and T2, with some individuals reporting a decrease and others reporting an increase. SNA tended to decrease in general. In terms of ANB, the male participants displayed a decrease from T1 to T2. Treatment of a skeletal Class II malocclusion with the mandibular anterior repositioning appliance (MARA) caused an increase in the sagittal posterior airway space (PAS) diameter and, thereby, might be effective against obstructive sleep apnea.

Outcome differences after orthodontic camouflage treatment in hypo- and hyperdivergent patients - A retrospective cephalometric investigation

OBJECTIVES

To compare differences in outcome in skeletal and dental parameters in hypo- and hyperdivergent Class II patients after extraction of upper first premolars and comprehensive orthodontic treatment.

MATERIALS AND METHODS

37 Class-II-patients with dental camouflage treatment were divided into a hypo- (n = 18) or a hyperdivergent (n = 19) group depending on the mandibular plane angle (hypo: < 34° or hyper: ≥ 34°). Lateral cephalograms were available before (T1) and after (T2) treatment and were analyzed with customized measurements. Data from a growth survey served as a control and were used to calculate the actual treatment effect. Data were analyzed by one-sample Student's t-tests and independent Student's t-tests. Statistical significance was set at p < 0.05.

RESULTS

The measurements showed similar changes in both groups. The effects were mainly dentoalveolar. Hypodivergent patients showed an almost equal increase in anterior and posterior facial height, while hyperdivergent patients only showed an increase in anterior facial height.

CONCLUSIONS

In hyperdivergent patients, the anterior facial height increases despite camouflage treatment. This indicates a tendency towards bite opening and backward rotation of the mandible. Hypodivergent patients do not experience deepening of the bite.

CLINICAL RELEVANCE

In hyperdivergent patients with upper first premolars extraction the anterior facial height increased differently than in hypodivergent patients. This should be considered if a bite opening is a possible contraindication to treatment.

Effects of fixed functional orthodontic treatment in hypodivergent and hyperdivergent class II patients-a retrospective cephalometric investigation

OBJECTIVE

To compare skeletal and dentoalveolar changes after orthodontic treatment of class II malocclusion in patients with hypodivergent and hyperdivergent growth patterns through cast splint fixed functional appliances (FFA).

MATERIALS AND METHODS

N = 42 out of n = 47 patients with mandibular plane angles < 34° or ≥ 34° were divided into a hypodivergent (n = 24) and a hyperdivergent (n = 18) group. All patients received a single-step mandibular advancement protocol through an FFA. Lateral cephalograms were analyzed after initial leveling and alignment (T1) and immediately after FFA removal (T2). The therapeutic effect was calculated through comparison with age-matched controls from a growth survey. Statistical significance was set at p < 0.05.

RESULTS

Hypodivergent and hyperdivergent patients showed different treatment outcomes, but significant differences existed only for overbite and interincisal angle. Nearly all measurements suggested similar treatment-related changes for both groups with exception for dentoalveolar parameters.

CONCLUSION

Treatment with FFA causes similar skeletal and dentoalveolar effects in hypodivergent and in hyperdivergent patients. The correction of overjet and molar relationship is mainly caused by dentoalveolar changes.

CLINICAL RELEVANCE

Hyperdivergent patients do not respond unfavorably to FFA treatment compared to hypodivergent patients. Lower incisor protrusion occurs more pronounced in hypodivergent patients. The growth pattern ought to be considered when choosing FFA for class II treatment.

Retrospective study on the pharyngeal airspace in the lateral cephalogram - A mathematical model to predict changes due to bimaxillary orthognathic surgery

The aim of this study was the development of a statistical model for reliable prediction of Posterior Airway Space (PAS) changes in lateral cephalograms (LCR) of patients after bimaxillary orthognathic surgery. The LCRs of patients who underwent bimaxillary orthognathic surgery were retrospectively analyzed. The anteroposterior dimension of the PAS was measured at three levels in the pre-operative and postoperative LCR: On the nasopharyngeal (SPAS), oropharyngeal (MAS), and hypopharyngeal level (IAS). The data of 139 patients were collected. The following changes of the PAS were measured: in class II patients SPAS: 0.291 mm (SD = 2.570 mm); MAS: 2.444 mm (SD = 2.986 mm); IAS: 0.750 mm (SD = 3.017 mm); in class III patients SPAS: 1.377 mm (SD 3.212 mm); MAS: 0.962 (SD: = 3.135 mm); IAS: 0.370 mm (SD = 3.468 mm). Linear regression analysis showed for class II patients, a significant influence of mandibular movement on MAS (p = 0.049) and a significant effect of maxillary and mandibular movements on SPAS (p = 0.001) and MAS (p = 0.022) in class III patients. The other jaw displacements had no significant impact on the investigated PAS levels. While the presented method does not permit exact prediction of the dimension of the PAS, it is still an easily accessible method of orientation for the surgeon. The surgeon can initiate three-dimensional examinations to provide exact three-dimensional prediction based on this calculation.