Titanium alloy vs. stainless steel miniscrews: an in vivo split-mouth study

OBJECTIVE

To compare in vivo Titanium Alloy (TiA) with Stainless Steel (SS) miniscrews Temporary Anchorage Devices (TADs) using removal torque and Scanning Electron Microscopic (SEM) analysis.

PATIENTS AND METHODS

15 subjects (6 males and 9 females) who required maximum anchorage were recruited. For each patient, a TiA TAD and a SS TAD with same length and width were implanted following a randomized split-mouth study design. Retraction was carried out with nickel-titanium spring ligated directly from the anterior hooks of the archwire to the TADs to produce 90 to 100 g of force. When no further anchorage supplementation was needed, the TADs were removed. The removal torque values were registered with a digital screwdriver. After removal, the TADs were collected in a fixed solution and examined using SEM and X-ray microanalysis.

RESULTS

All TADs remained intact, with a 100% success rate. There was no difference in removal torque between TiA and SS miniscrews (4.4 ± 1.3 N-cm and 5.1 ± 0.7 N-cm, respectively). All specimens' loss of gloss with signs of biological contaminations resulted in a dull implant surface. SEM photomicrographs of TiA miniscrews showed predominantly blood cells while SS miniscrews showed the precipitation of an amorphous layer with low cellular component. There was no difference in spectroscopic analysis between TiA and SS miniscrews.

CONCLUSIONS

TiA and SS miniscrews had comparable removal torque values. SEM photomicrographs showed no evidence of osseointegration with both TADs having similar biological responses.

Orthopaedic treatment effects of functional therapy on the sagittal pharyngeal dimensions in subjects with sleep-disordered breathing and Class II malocclusion

The purpose of this cephalometric study was to evaluate the craniofacial changes induced by functional treatment of mandibular advancement with special regard to pharyngeal sagittal airway dimensions, tongue and hyoid bone position in subjects with sleep-disordered breathing (SDB) and dentoskeletal Class II malocclusions compared with an untreated Class II control group. 51 subjects (24 female, 27 male; mean age 9.9 ± 1.3 years) with Class II malocclusion and SDB consecutively treated with a functional appliance (Modify Monobloc, MM) were compared with a control group of 31 subjects (15 males, 16 females; mean age 10.1 ± 1.1) with untreated Class II malocclusion. For the study group, mode of breathing was defined by an otorhinolaryngologist according to complete physical examination. The parents of all participants completed a modified version of the paediatric sleep questionnaire, PSQ-SRBD Scale, by Ronald Chervin (the Italian version in 22 items form) before and after the trial. Lateral cephalograms were available at the start and end of treatment with the MM. Descriptive statistics were used for all cephalometric measurements in the two groups for active treatment changes. Significant, favourable skeletal changes in the mandible were observed in the treated group after T2. Significant short-term changes in sagittal airway dimensions, hyoid position and tongue position were induced by functional therapy of mandibular advancement in subjects with Class II malocclusion and SDB compared with untreated controls. After orthodontic treatment, a significant reduction in diurnal symptoms was observed in 45 of the 51 participants who had received an oral appliance. Orthodontic treatment is considered to be a potential therapeutic approach for SDB in children. Orthodontists are playing an increasingly important role in managing snoring and respiratory problems by oral mandibular advancement devices and rapid maxillary expansion.

Interceptive management for multiple eruption disturbances: a follow-up evaluation

AIM

The aim of this report was to show the management of a case with an impacted central maxillary incisor caused by odontoma in a young patient with two mesiodentes in the region of the nasal floor.

CASE REPORT

A 9-year-old girl was seen in the Department of Orthodontics of the University of Rome 'Tor Vergata'. Radiographic images showed intraosseous impaction of the maxillary right central incisor due to an odontoma. The treatment plan consisted of three stages: removal of the odontoma; rapid maxillary expansion (RME) in order to improve the intraosseous tooth position; surgical exposure and orthodontic traction of the impacted central incisor to its right position. At the end of the treatment the patient showed stable occlusal, functional, and periodontal results. In our therapeutic strategy the application of RME may improve the intraosseous position of incisor, minimizing space loss and surgical intervention to recover the impacted tooth. A three-year follow-up of the stability and periodontal health showed that the tooth placed in the occlusion maintained both esthetics and function.

Radiographic assessment of maxillary incisor position after rapid maxillary expansion in children with clinical signs of eruption disorder

BACKGROUND AND OBJECTIVE

In this study we assessed the influence of rapid maxillary expansion (RME) on the intraosseous vertical position and inclination of the impacted incisors diagnosed at an early developmental stage on panoramic radiographs and subsequently treated by surgical removal of the obstacle.

MATERIALS AND METHODS

Following surgical removal of the obstacles to incisor eruption (T1), a group of 34 subjects (mean age 8 years 11 months ± 11 months) underwent RME, while a group of 28 subjects (mean age 9 years 1 month ± 1 year) was monitored after surgery without further treatment. At T2 (on average 10 months after T1), the prevalence rate of subjects with erupted incisors was recorded. The measurements were taken on the panoramic radiographs at T1 and T2 to assess the vertical position and angulation of delayed unerupted incisors.

RESULTS

At T2, impacted incisors erupted in 82.4% of the patients in the RME group versus 39.3% of those in the monitored group (χ(2) =8.45, p<0.001). All the patients treated with RME showed an improvement in the vertical and angular position of the unerupted teeth. Logistic regression revealed RME therapy as the only significant predictive variable (p<0.001) for successful eruption of the delayed incisors at T2.

CONCLUSION

RME in early mixed dentition appears to be an effective procedure to increase the prevalence rate of impacted maxillary incisor eruption.

Rapid maxillary expansion: effects on palatal area investigated by computed tomography in growing subjects

AIM

The aim of this prospective study was to evaluate the effects of rapid maxillary expansion (RME) on the palatal area as assessed by low-dose CT before treatment (T0), at the end of active expansion (T1) and after a retention period of 6 months (T2).

MATERIALS AND METHODS

The study sample comprised 17 prepubertal subjects (mean age 11.2 years) with constricted maxillary arches. Total amount of expansion was 7 mm in all subjects. Multi-slice low-dose CT scans were taken at T0, T1, and T2. On axial CT scanned images a circle line corresponding to the palatal area was drawn and the area inside the circle registered at all three observation times. The area was measured in mm². Statistical comparisons were carried out with Friedman test with post-hoc tests (P<0.05).

RESULTS

The palatal area showed a significant increase from T0 to T1 and from T0 to T2 as a consequence of the opening of the midpalatal suture after RME.

CONCLUSION

Opening the midpalatal suture by using orthopedic forces allowed to extend the area of the maxilla. After a 6-months retention period the palatal area demonstrated a stable increase due to a bone deposition along the midpalatal suture in both the anterior and posterior parts of the maxilla.