Comparison between twin block appliance and mandibular advancement on clear aligners in the improvement of airway dimension: incremental versus maximum bite advancement.

Objective: The aim of the present retrospective study was to compare the changes resulting from treatment using the MA and the TB with special regard to the oro-and naso-pharyngeal sagittal airway dimensions in subjects with dentoskeletal Class II malocclusions and positive history of Sleep Disorder Breathing (SDB) diagnosed through the Pediatric Sleep Questionnaire (PSQ). Materials and methods: This retrospective study involved 2 groups of subjects: patients treated with Twin Block (TB group: n = 22, 10 males, 12 females; mean age 12.0 ± 1.3 years) and patients treated with Mandibular Advancement (MA group: n = 23, 11 males, 12 females; mean age 12.2 ± 1.1 years). Pretreatment (T1) and posttreatment (T2) lateral cephalograms were analyzed. All patients underwent the PSQ to diagnose SDB. Results: In both treated groups there was an increase in the airways dimensions and an improvement in symptoms related SDB. The statistical comparison of the changes between T1 and T2 in the TB group showed a significant increment in upper airway size (PNS-AD2, +1.50 mm + -3.30; McNamara's upper pharynx dimension, +2.21 + -4.21) after active treatment. The MA group showed similar results during active treatment with a significant increase in both upper (PNS-AD2, +2.72 + -2.65; McNamara's upper pharynx dimension, +2.97 + -3.07) and lower (PNS-AD1, +2.17 mm + -3.54) airway size. Conclusions: Despite the different structure of these two devices and the different advancement protocols, both appliances were valuable as a suitable treatment option for Class II patients with respiratory disorders, inducing an increase of upper and lower airway size and a significant reduction in diurnal symptoms.

Predictability of expansion movements performed by clear aligners in mixed dentition in both arches: a retrospective study on digital casts.

BACKGROUND: to evaluate the predictability of expansion achieved in patients in early mixed dentition treated with Clear Aligners (CA), analyzing the efficiency of the expansion at the end of the first set of aligners and at the end of the therapy in the upper and lower arch. METHODS: 36 patients (20 F, 16 M; mean age 8.3 ± 1.5 years) were selected retrospectively from the Department of Orthodontics of the Hospital of Rome "Tor Vergata". All subjects were treated with CA with no other auxiliaries than attachments. For each patient a standardized sequential expansion protocol was planned for both arches. Digital dental casts were created at three observation periods from an intraoral scanner: prior to treatment (T0), at the end of the first set of aligners (T1), at the end of treatment (T2). The 3D models in planned position determined by the first Clincheck (CC) were obtained for comparison with T1 and T2. Six linear transversal measurements were used to evaluate the dimensional changes and the predictability of expansion movements, comparing T1-CC and T2-CC. RESULTS: a statistically significant increase within the pre-treatment and the final outcomes for all the variables examined was found. In the upper arch, the greatest level of predictability was detected at the level of the first (46.44%) and second deciduous molar width (44.95%) at T1. The analysis of T2-CC changes showed a significant increase in the percentage of predictability of expansion at the level of the first permanent molars, at mesial (54.86%) and distal (58.92%) width. In the lower arch, a higher percentage of predictability than the upper arch was reported at T1-CC and T2-CC, with the greatest values at the level of second (T1-CC: 48.70%; T2-CC: 75.32%) and first deciduous molar width (T1-CC: 45.71%; T2-CC: 72.75%). CONCLUSIONS: CA can induce significant transversal increments. The predictability of expansion is variable, but it did not exceed the 50% during the first set of aligners. It was necessary to apply refinement set to achieve a good predictability for expansion of about 70%. The expansion in the lower arch was observed to be more predictable than in the upper arch.

Severe Crowding Associated with Lower Canine Premature Resorption: Interceptive Treatment with Clear Aligners-A Pilot Study.

BACKGROUND: Early mixed dentition represents a critical phase since crowding conditions can occur. The interceptive resolution of dental crowding allows favorable arch and occlusal development. The aim of the present investigation was to evaluate dentoalveolar changes of clear aligner treatment planned to manage lower incisor crowding, loss of arch length, and midline deviation in early mixed dentition. METHODS: A total of 13 patients (7 females, 6 males, 9.4 ± 1.2 age) treated with clear aligners were selected. Arch dimensions and incisor inclinations were evaluated before (T0) and at the end of interceptive treatment (T1). A paired t-test was chosen to compare T1-T0 changes. The level of significance was set at 5%. RESULTS: The greatest significant increase in mandibular width was observed at the level of the first deciduous molars (+2.44 ± 1.4 mm), followed by the second permanent molars (+2.16 ± 1.4 mm). Lower arch length and arch depth showed a statistically relevant increase (2 ± 0.6 mm and 4.5 ± 1.6 mm, respectively). The mean lower dental midline changes were statistically significant (1.42 ± 0.73 mm). CONCLUSIONS: Early treatment with clear aligners, including the combination of transversal arch development, maintenance of leeway space, and guidance of eruption, represents a valid treatment strategy in early mixed dentition to manage arch crowding and occlusion development.

Experimental validation of mechanical oscillating IPR system.

BACKGROUND: Interproximal enamel reduction (IPR) is a clinical procedure which involves reduction and anatomic recontouring of interproximal surfaces of enamel as a method of gaining space. The biological effects related to this clinical procedure have long been discussed. Thus, the aim of this study was to evaluate the enamel reduction efficiency and the effects on enamel surfaces of the oscillating mechanical system for interproximal enamel reduction (IPR). METHODS: Fifteen complete oscillating IPR sequences included one opener (0.1 mm), two metallic strips for active IPR phase (0.2 and 0.3 mm), three resin strips for active and initial polishing phases (0.4 and 0.5 mm), and one resin strip for polishing phase (0.15 mm). Sequences were selected and tested on fifteen freshly extracted teeth by means of tribological tests with alternative dry-sliding motion (Linear Reciprocating Tribometer; C.S.M. Instruments, Peseaux, Switzerland). A 3D analysis of treated surfaces was performed by using a TayMap software. Then, enamel surfaces were qualitatively evaluated before and after the tribological analysis, with a FEI Quanta 200 (FEI, Hillsboro, OR, USA) in high vacuum at 30.00 kV. Images were acquired at a 30×, 100× and 300× magnification. RESULTS: Minimum surface irregularities were observed on all treated enamel surfaces when compared with untreated ones. The 3D analysis showed a uniform wear pattern after tribological tests. Meanwhile, the SEM analysis revealed smooth and regular wear lines on treated surfaces after the entire mechanical IPR sequence. The macroscopic irregularities illustrated can be considered similar to those of untreated surfaces. CONCLUSIONS: The adoption of a standardized oscillating IPR sequence allows an efficient reduction of the interproximal enamel, leaving regular and harmonious surfaces. Adequate polishing procedures should always be performed at the end of active IPR phases in order to guarantee a good long-term prognosis and proper respect of biological structures.

Soft tissue facial profile in Class III malocclusion: long-term post-pubertal effects produced by the Face Mask Protocol.

OBJECTIVES: The objective of this study was to analyze soft tissue changes produced by rapid maxillary expansion and facial mask therapy in growing Class III patients. MATERIALS: The treated group consisted of 32 Caucasian patients (15 females and 17 males) with dentoskeletal Class III malocclusion treated with the Face Mask Protocol (FMP, rapid maxillary expander, facial mask, and removable lower bite-block). All patients were evaluated before treatment (T1; mean age, 8.4 years), at the end of active treatment (T2; mean age, 10.7 years), and at a post-pubertal follow-up observation (T3; mean age, 15.8 years). The treated group was compared with a matched control group of 20 untreated subjects (10 females and 10 males) with dentoskeletal Class III malocclusion. Statistical comparisons between two groups were performed with the independent samples t-test (P < 0.05). RESULTS: Significant improvements were found during the long-term T1-T3 interval for profile facial angle (-5.8°), nasolabial angle (-4.4°), mandibular sulcus (-10.3°), upper lip protrusion (+0.7 mm), and lower lip protrusion (-1.1 mm) in the treated group. No significant post-pubertal effects were found in terms of lower face percentage between two groups. LIMITATIONS: This study has a retrospective design and it used a historical control sample. CONCLUSION: The FMP induced positive effects on soft tissue facial profile with a good long-term post-pubertal stability.