Residents’ journal review

Abstract

Deciding between orthopedic and surgical maxillary expansion is not guided by a hard and fast rule. Although dental tipping is expected in tooth-borne expansion, the extent of transverse correction achieved by buccal movement of the posterior segment beyond the limits of the alveolar housing and the cortical plate increases with skeletal age. Maturation indexes, most commonly the hand and wrist method and the cervical vertebrae method (CVM), are reasonable indicators of remaining skeletal growth but not of the degree of fusion of the midpalatal suture. Therefore, a method to classify the extent of maturation based on the morphology of the midpalatal suture assessed with cone-beam computed tomography (CBCT) has considerable clinical implications. The investigators sought to use such a method, developed by Angelieri et al (Angelieri F, Cevidanes LH, Franchi L, Goncalves JR, Benevides E, McNamara JA Jr. Midpalatal surture maturation: classification method for individual assessment before rapid maxillary expansion. Am J Orthod Dentofacial Orthop 2013:144:759-69) to predict the maturation of the midpalatal suture and to identify a relationship with conventional maturation indexes, if one exists. Midpalatal suture morphology was examined in 99 subjects (ages, 6-20 years) in all planes of space using CBCT images and classified into 5 stages (A-E) according to the classification of Angelieri et al. Hand and wrist method and CVM showed statistically significant correlations (0.904 and 0.874, respectively) with CBCT stage. Stage D or E (fusion of the suture) was not observed in either the male or female group before Suture Maturation Index stage 6. There was no fusion before stage 3 or 4 of the CVM in girls or boys, respectively. The authors concluded that orthopedic maxillary expansion may be recommended before stage 6 in the SMI and before stage 3 in the CVM, whereas a surgical approach may be considered after these stages are recognized. Direct assessment of the midpalatal suture using CBCT images may be clinically beneficial. Reviewed by Ella Botchevar Orthodontic mini-implants (OMIs) have been an invaluable asset to clinicians in contemporary orthodontics. Obtaining absolute anchorage with skeletal implants has been paramount in facilitating tooth movement that might otherwise require extraction of teeth or prolonged use of extraoral anchorage. In uncooperative patients, OMIs have been used to increase predictable treatment outcomes largely because of the wide possibilities of placement. Although success rates are high, failures have been reported from instability, fracture of the OMI, root damage, and inflammation. Treatment success relies on obtaining an effective interface between the OMI and surrounding bone tissues. The authors of this study examined the effects of various surface treatments on the osseointegration and bone-cutting ability of OMIs. Three self-drilling OMIs were compared based on surface treatment: acid etched, resorbable blasting media, and partial resorbable blasting media (hybrid). To compare bone-cutting capacity, artificial bone blocks were made of polyurethane foam to simulate corticocancellous bone. For the comparison of removal torque values, 25 male rabbits had implants placed in tibias and evaluated at 1, 2, 4, and 8 weeks. Histologic analysis for osseointegration was completed with light microscopy and scanning electron microscopy. The results showed that the etched and hybrid groups had lower bone-cutting capacity when compared with the machined (control) group. The hybrid group removal torque significantly increased up to 2 weeks and by 8 weeks was the highest among all groups tested. After evaluation by scanning electron microscopy, only the hybrid group had detectable bone-like tissue. The ability to increase stability while maintaining fracture resistance relies on both macro and micro designs of OMIs. This study showed that hybrid treated OMIs would produce the most stability, offering increased predictability during treatment. Reviewed by Joseph Facciolo The use of mini-implants as orthodontic anchorage has increased significantly in the last decade. Ease of placement and elimination of patient compliance has led to their increased usage, but success depends mainly on cortical bone thickness (CBT). Bone that is either too thin or too thick is a significant risk factor for implant failure, which can lead to loss of anchorage. Therefore, it would be advantageous for the clinician to be able to predict which patients might be at higher risk for implant failure due to facial type. Previous studies have looked at CBT in the posterior only and shown that cortical bone is significantly thinner in high-angle patients compared with low-angle patients. The authors of this study aimed to investigate both posterior and anterior CBT in low-, normal-, and high-angle patients. Cone-beam computed tomography scans were used to analyze the CBT at 4 and 7 mm apical to the crest of the labial and lingual/palatal alveolar bone. The results showed no significant differences in anterior CBT, but there were significant differences in CBT of the buccal aspects of the posterior maxilla and mandible. The CBT was significantly less in high-angle patients on the buccal aspect between the second premolars and first molars, and on the palatal side of the maxillary lateral incisors. High-angle subjects consistently had sites with less than 1 mm of CBT. Although this study has limitations, it provides valuable information to clinicians regarding placing mini-implants in high-angle patients. For these patients, the clinician must avoid areas where CBT is thinnest as shown in this study or consider using other forms of anchorage. Reviewed by Meghan Graham Authors of previous studies have concluded that bonded palatal expanders and quad helix appliances can control the vertical dimensions during expansion. These authors looked at the vertical changes with 2 types of palatal expanders: quad helix and bonded rapid maxillary expanders. They compared 17 patients treated with the quad helix and 18 patients treated with the bonded expander before treatment and after treatment using 8 cephalometric landmarks. Each group was also compared with untreated growth predictions using the Ricketts growth prediction module. No vertical changes were found between the before and after treatment times in the quad helix group. However, there was an increase in L6-MP during treatment in the bonded expander group. Between the 2 groups after treatment, convexity was greater for the bonded expander group; therefore, there was a greater tendency toward a Class II skeletal pattern. The lower facial height, total facial height, and Frankfort-mandibular plane angle were greater for the bonded expander group. The facial axis value was also greater for the quad helix group. When comparing treatment results with untreated predicted growth values, the quad helix group seemed to maintain or even decrease lower facial height. However, the bonded expander group showed a lower U6-PP value, suggesting intrusion of the maxillary first molar. The authors concluded that both expanders adequately maintain the vertical dimension in growing skeletal Class I and Class II patients, with the quad helix expander showing more control over skeletal vertical measurements. Reviewed by Sarah AlMugairin The best timing for orthodontic treatment is linked to the patient's growth spurt. However, studies do not agree regarding the best way to measure growth. Several methods including third molar mineralization, spheno-occipital synchondrosis fusion, chronologic age, and cervical vertebrae maturation have been studied to locate the growth spurts. The authors' objective was to assess the correlation between these methods and skeletal maturation. The study was conducted retrospectively on 116 patients. All subjects had panoramic, lateral cephalometric, and cone-beam computed tomography radiographs. Any patient with a craniofacial syndrome, third molar agenesis, or a history of trauma causing fracture to the mandibular angle area was excluded. Cervical vertebral maturation was determined using the method proposed by Lamparski and detailed by Hassel and Farman. Dental age was measured according to the method of Demirjian et al and scored from A to H. The degree of spheno-occipital synchondrosis was assessed using Frankin and Flavel's 4-stage system. A strong relationship was noted with Spearman correlation coefficients between age and cervical vertebrae maturation for males, but it was moderate for females. However, a strong correlation was noted in both sexes between age and third molar mineralization. The relationships between age and spheno-occipital synchondrosis fusion were found to be very strong for males and strong for females. The results of the study show good relationships between third molar mineralization on panoramic radiographs, cervical vertebrae maturation on lateral cephalometric radiographs, and SOS fusion on cone-beam computed tomography radiographs and degree of skeletal maturation in the sample population studied. This study is unique in that it compared 3 methods; any of these may be used to measure the degree of skeletal maturation upon availability of radiographs. Reviewed by Nada Tashkandi Orthodontic treatment is often associated with pain and discomfort; as the use of miniscrews becomes more common in orthodontics, they are yet another source of discomfort during treatment. The objective of this study was to investigate and compare the discomfort and pain experienced between insertion of miniscrews and extraction of premolars. The pain and discomfort experienced after tooth extraction can be used as a reliable reference, since this procedure is commonly used and accepted in orthodontics. Eighty adolescent patients were included in this study. All were treated with extraction of maxillary first premolars, and half had miniscrews placed buccally between the second premolar and the first molar for anchorage support. Patient-reported questionnaires were used to assess pain, discomfort, impact on daily activities, and functional jaw impairment at baseline, the evening after premolar extraction, 1 week after premolar extraction, the evening after miniscrew placement, and 1 week after miniscrew placement. The authors found that after placement of miniscrews patients reported significantly lower levels of pain and discomfort compared with after premolar extractions. Patients also reported significantly fewer problems when taking a big bite and drinking after miniscrew placement than after premolar extraction. Leisure activities were less often reported to be disturbed after miniscrew placement as well. In general, the levels of discomfort and intensity of pain reported with miniscrew placement were moderate. The conclusions of this study allow us to recommend the use of miniscrews during orthodontic treatment without undue concern for the pain and discomfort experienced by patients. Reviewed by MaryEvan Thacker Dentofacial orthopedics can restrain or redirect growth. Orthopedic correction of Class II malocclusions by growing mandibles is the ideal treatment because of mandibular retrognathia. However, some believe that mandibular growth cannot be achieved by these appliances. The authors of this study aimed to evaluate and compare changes after functional treatment and after fixed appliances. A retrospective analysis was performed on cephalograms of 125 patients (77 female, 48 male) at 3 time points: before treatment, after functional treatment, and after fixed appliances. Most patients were Caucasian with a cervical vertebral maturation stage of 2 or 3. All had at least a half cusp Class II molar relationship bilaterally and an ANB angle of at least 4.5°. The appliances used included 7 different activators. The patients were instructed to wear the appliance at least 14 hours daily. Cephalograms were analyzed using Steiner and Jarabak norms. Longitudinal measures analysis was used to evaluate the changes for each measurement independently. Changes between time intervals were compared by sex, type of appliance, and dental age. The authors found a decrease of SNA angle (0.38° ± 0.77; P <0.05), an increase of SNB angle (1.46° ± 0.66; P <0.05), and a less convex profile (increased N′-Sn′-Pog′ of 2.93° ± 0.87; P <0.05) after functional treatment. Class II correction was mostly due to dentoalveolar changes in incisor position. No significant changes in incisor position occurred after functional treatment. Decreases of both SNA angle (1.17° ± 0.75; P <0.001) and SNB angle (0.41° ± 0.64; P <0.05) were seen after fixed appliances. The authors concluded that functional appliances are a valid treatment option for growing patients. Reviewed by Cecilia M. Deller