Efficacy of orthopedic treatment with protraction facemask on skeletal Class III malocclusion: a systematic review and meta-analysis.

The objective of this systematic review was to estimate the efficacy of protraction facemask on the correction of Class III malocclusion in the short term. A systematic review of articles was performed using different electronic databases (PubMed, Ovid, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, and Google Scholar). Search terms comprised 'orthopedic treatment' and 'Class III malocclusion'. The selection criteria were set in order to include in this review only randomized clinical trials (RCTs) performed treating with facemask Class III growing patients. Studies' selection, data extraction, and risk of bias's assessment were executed independently by two authors using pre-defined data forms. All pooled analyses of data were based on random effects models. A pre-specified subgroup analysis was planned to evaluate the effect of preliminary rapid palatal expansion on facemask efficacy. Three RCTs met our inclusion criteria. In total, data from 155 patients (92 treated and 63 controls) were collected. The treated group showed the following significant changes: ANB° +3.66° [95%CI (2.58, 4.74)]; SNA° +2.10 [95%CI (1.14, 3.06)]; SNB° -1.54 [95%CI (-2.13, -0.95)]; SN-palatal plane -0.82° [95%CI (-1.62, -0.02)]; and SN-mandibular plane +1.51 [95%CI (0.61, 2.41)]. Heterogeneity varied from low to moderate (mean I(2) value: 41.4 ± 20.8). Facemask is effective correcting Class III malocclusion in the short term. The skeletal modifications induced by facemask are forward displacement of maxilla, backward displacement of mandible, clockwise rotation of the mandibular plane, and counterclockwise rotation of the maxillary plane.

Identification of genetic variation and haplotype structure of the canine ABCA4 gene for retinal disease association studies.

Over 200 mutations in the retina specific member of the ATP-binding cassette transporter superfamily (ABCA4) have been associated with a diverse group of human retinal diseases. The disease mechanisms, and genotype-phenotype associations, nonetheless, remain elusive in many cases. As orthologous genes are commonly mutated in canine models of human blinding disorders, canine ABCA4 appears to be an ideal candidate gene to identify and study sequence changes in dogs affected by various forms of inherited retinal degeneration. However, the size of the gene and lack of haplotype assignment significantly limit targeted association and/or linkage approaches. This study assessed the naturally observed sequence diversity of ABCA4 in the dog, identifying 80% of novel variations. While none of the observed polymorphisms have been associated with blinding disorders to date, breed and potentially disease specific haplotypes have been identified. Moreover, a tag SNP map of 17 (15) markers has been established that accurately predicts common ABCA4 haplotypes (frequency > 5%) explaining >85% (>80%) of the observed genetic diversity and will considerably advance future studies. Our sequence analysis of the complete canine ABCA4 coding region will clearly provide a baseline and tools for future association studies and comparative genomics to further delineate the role of ABCA4 in canine blinding disorders.

Opinions of American and Swedish orthodontists about the role of erupting third molars as a cause of dental crowding.

OBJECTIVE: To compare the opinions of Swedish orthodontists and American orthodontists regarding the association between third molar eruption and dental crowding. MATERIALS AND METHODS: A survey was distributed to Swedish orthodontists (n = 230) asking their views on the force exerted by erupting third molars, its relationship to crowding, and their recommendations for prophylactic removal. Results were compared with those from a similar study conducted in the United States. Chi square analysis was used to determine differences in responses to questions between Swedish and American orthodontists. P < or = .05 was considered significant. RESULTS: Both Swedish and American orthodontists believed that lower third molars were more likely than upper third molars to cause force (65% and 58% for Swedish and American orthodontists, respectively) and crowding (42% and 40%, respectively). No statistically significant differences were seen between the answers of American and Swedish orthodontists regarding the role of upper and lower third molars in causing crowding. Although only 18% of Swedish orthodontists "generally" or "sometimes" recommended prophylactic removal of mandibular third molars, 36% of American orthodontists "generally" or "sometimes" recommended removal (P < .0001). CONCLUSIONS: Most orthodontists in the United States and Sweden do believe that erupting lower third molars exert an anterior force; however, they also believe that these teeth "rarely" or "never" cause crowding of the dentition. The reason that more American orthodontists recommend prophylactic removal of mandibular third molars remains unexplained.

Moving an ankylosed central incisor using orthodontics, surgery and distraction osteogenesis.

When a dentist replants an avulsed tooth, the repair process sometimes results in the cementum of the root and the alveolar bone fusing together, with the replanted tooth becoming ankylosed. When this occurs, the usual process of tooth movement with bone deposition and bone resorption at the periodontium cannot function. If dental ankylosis occurs in the maxillary incisor of a growing child, the ankylosed tooth also cannot move vertically with the subsequent vertical growth of the alveolar process. This results in the ankylosed tooth leaving the plane of occlusion and often becoming esthetically objectionable. This report describes a 12-year-old female with a central incisor that was replanted 5 years earlier, became ankylosed, and left the occlusal plane following subsequent normal vertical growth of the alveolar process. When growth was judged near completion, the tooth was moved back to the occlusal plane using a combination of orthodontics, surgical block osteotomy, and distraction osteogenesis to reposition the tooth at the proper vertical position in the arch. This approach had the advantage of bringing both the incisal edge and the gingival margin of the clinical crown to the proper height in the arch relative to their antimeres. Previous treatment procedures for ankylosed teeth have often involved the extraction of the affected tooth. When this is done, a vertical defect in the alveolar process results that often requires additional bone surgery to reconstruct the vertical height of the alveolar process. If the tooth is then replaced, the replacement tooth must reach from the final occlusal plane to the deficient ridge. This results in an excessively long clinical crown with a gingival height that does not match the adjacent teeth.

Condylar positional changes after mandibular advancement surgery with rigid internal fixation.

The purpose of this retrospective investigation was to describe condylar positional changes in patients after mandibular advancement surgery. By superimposing on clearly identifiable cephalometric landmarks (ie, mandibular symphysis and rigid fixation screws), condylar positional changes from immediately after surgery to orthodontic appliance removal were extrapolated. Although the mandibular symphysis generally moved in either an anterior or posterior direction after surgery, condylar movements were exclusively in an upward vertical direction. Correlations were found between several measured variables, including a tendency for increased superior postsurgical movement of the condyles with increasing magnitudes of surgical advancement of the mandible. This long-term instability of skeletal relationships may be caused by a wide variety of interacting factors and events.

Evaluation of dental midline position.

Maxillary midline position relative to the facial midline is stressed as an important diagnostic feature in orthodontic treatment planning. Depending on the patient, however, movement of the dental midline to be coincident with the facial midline may be difficult to achieve. In addition, evaluation of dental midline position may be complicated if other midline facial structures are not well aligned. The two objectives of the current study were to determine how far the maxillary dental midline could deviate from the facial midline and still be considered aesthetically acceptable, and to determine how the position of various midline facial landmarks affect overall facial aesthetics. One hundred twenty individuals, including orthodontists, general dentists, orthodontic patients, and parents of patients, evaluated digitally altered images of two patient-subjects to rate the acceptability of dental midline deviations and to prioritize the importance of location of various midline facial structures. The mean threshold for acceptable dental midline deviation was 2.2 +/- 1.5 mm. There was a significant difference in deviation thresholds between the two patient-subjects (P < .05). Orthodontists and dentists were significantly less tolerant of midline deviations than were patients (P < .001), with the tolerance of parents in between. When deviations of various midline facial structures were evaluated, photographs with maxillary midline and/or nose deviations were considered less aesthetic (P < .001). There were no apparent differences noted among orthodontists, dentists, patients, and parents in this part of the study.

Orthodontic treatment priority: a comparison of two indices.

Approval for state sponsored funding of orthodontic treatment is often decided using an index of malocclusion. The purpose of this study was to determine whether two indices used for prioritizing patients would identify different groups of individuals qualifying for orthodontic treatment funding approval. In addition, the characteristics of patients approved using different indices were compared. The records of 40 patients previously submitted for state medicaid funding approval were evaluated by three study examiners using two orthodontic treatment priority indices, the Salzmann Handicapping Malocclusion Assessment (Salzmann) and the Index of Orthodontic Treatment Need (IOTN). Comparisons were made between state medicaid and study examiner Salzmann scores, rankings, and funding decisions, and between study examiner Salzmann rankings, IOTN rankings, and funding decisions. Correlation and rank correlation coefficients between the state and study examiners' Salzman scores were high (r = 0.74; p < 0.001, and R = 0.77; p < 0.001). Rank correlation analysis of the study examiners' Salzmann and IOTN values demonstrated a weaker relationship (R = 0.40; p < 0.02). Agreement on funding decisions, evaluated by the Kappa statistic, was greater between the two Salzmann evaluations (K = 0.57) than between the study examiners' Salzmann and IOTN evaluations (K = 0.14). As expected, depending on the method used to determine orthodontic treatment funding priority, different patients were likely to be identified for treatment approval. The characteristics of patients whose treatment was approved was closely related to the criteria defined by the method employed.

Lower arch perimeter preservation using the lingual arch.

The purpose of this investigation was to determine whether the placement of a mandibular lingual arch maintained arch perimeter in the transition from the mixed to the permanent dentition, and if so, whether it was effective at preventing mesial migration of first permanent molars, or whether this migration still occurred en masse, by increased lower incisor proclination. Thirty patients were randomly assigned to either a treatment group (N = 14, mean age = 11.5 years) or a control group (N = 16, mean age = 11.3 years). Study models, cephalograms, and tomograms of the patients, taken at the beginning and at the end of the study period, were examined. Statistically significant differences between groups were found for positional changes of mandibular first molars and incisors, and changes in arch dimensions. The results indicate that the lingual arch can help reduce arch perimeter loss, but at the expense of slight mandibular incisor proclination.

Effect of pumice prophylaxis on the bond strength of orthodontic brackets.

Pumice prophylaxis has long been accepted as a prerequisite for achieving adequate enamel etching during orthodontic bonding procedures. Three methods were used in this study to examine the effects of pumice prophylaxis on the bond strength of orthodontic brackets: (1) shear bond strength of brackets that were bonded to extracted premolars after surface preparation procedures, which either included or did not include prior pumice prophylaxis, was evaluated; (2) scanning electron microscopy (SEM) was used to examine the surface characteristics of teeth that had been etched with and without prior pumice prophylaxis; and (3) rate of bracket failure in patients who had had brackets bonded with and without prior pumice prophylaxis was recorded during an average treatment time of 18 months. No significant differences were noted in bond strength, general etched enamel surface characteristics, or bracket retention rates. Some specific differences, however, were noted on SEM in localized areas of the etched enamel surfaces, although these did not appear to affect the bond strength or bracket retention rates ultimately attained.

Class II subdivision treatment with tip-back moments.

Unilateral tip-back mechanics are challenging because of a number of undesirable side-effects associated with their use during orthodontic treatment. The purpose of this paper is to review the differential diagnosis and treatment planning of Class II subdivision malocclusions and present a treatment strategy based on a careful biomechanical analysis of the clinical situation. Emphasis is placed on the correction of molar axial inclination using unilateral tip-back moments in the treatment of dental asymmetries. Appliance design and treatment sequencing are also discussed.

The effects of lip bumper therapy in the mixed dentition.

A prospective clinical trial was undertaken to study the effects of 6 months of continuous lip bumper therapy on patients in the mixed dentition with mild-to-moderate mandibular arch perimeter deficiency. Thirty-four patients, ages 7.9 to 13.1 years (mean = 10.2), seeking treatment in the postgraduate orthodontic clinic of the Medical College of Virginia, presented possessing 3 to 8 mm of mandibular crowding, with both mandibular primary second molars, were randomly placed in either the treatment or nontreatment group. Treated subjects underwent continuous lip bumper therapy, whereas the control subjects were monitored without undergoing any active treatment, each for 6 months. Arch dimension changes were assessed with study models. Alterations of mandibular incisor position were measured from lateral cephalometric radiographs. Mandibular left permanent first molar position changes were determined from both lateral cephalometric and tomographic radiographs, with the resolution of each imaging technique in measuring molar tooth movement also compared. It was found that significant differences in mandibular incisor inclination, molar position, arch length, and arch perimeter existed between treated and untreated subjects. In addition, multiple observer analysis showed that cephalometric examination lacks sensitivity when used to measure molar movement.

Variability of facial photographs for use in treatment planning for orthodontics and orthognathic surgery.

Facial photographs are commonly used preoperatively for recording and analyzing skeletofacial and dentofacial deformities prior to orthodontics and/or orthognathic surgery. This study was undertaken to determine the reproducibility of facial photographs over time in any individual patient. Twenty subjects had full-facial frontal and lateral, frontal smile, and lip-to-tooth length (incisor show at rest) photographs taken on 5 different days over a 7- to 14-day period. A total of 18 linear and angular measurements were made on each set of photographs. Standard errors of the 18 measurements over time were generally moderate but varied widely, suggesting that facial photographs have the potential to provide reliable diagnostic information in some cases. In any individual patient, however, there were some variations within measurements that were clinically unacceptable. Measurements made from pictures of the smile were significantly less reliable than those taken at rest, and measurements of vertical head posture and lower lip length were found to be the least reliable. This study suggests that some measurements from facial photographs are generally reproducible over time, but significant individual variations do occur.

Simultaneous intrusion and retraction using a three-piece base arch.

Flared incisors and deep overbite are challenging to treat orthodontically. This paper describes the use of a three-piece base arch and Class I elastics to correct deep overbite while simultaneously closing spaces. An analysis of the biomechanics and a discussion of the appliance design are presented to help understand how the incisor axial inclination can be corrected and controlled during orthodontic therapy. A clinical example illustrates the treatment sequence.

Biomechanical considerations for orthodontic treatment of adults.

Biomechanical modifications made to accommodate orthodontic treatment of adult dentitions are generally minor and adhere to the basic laws of physics as they apply to all orthodontic tooth movement. Some adult presentations necessitate changes in treatment strategy from what would otherwise be employed in adolescent patients to achieve similar goals. In other cases, objective themselves may need to be modified because of a lack of growth potential, constraints of treatment mandated by the patient, or the presence of multiple missing or compromised teeth. The possibilities and limitations of orthodontic and dentofacial orthopedic treatment for adults are usually easier to define before beginning therapy than with adolescent patients because the unknown contribution that growth will make has already been discounted. By planning treatment and mechanotherapy taking into account the individual circumstances that may affect the patient's biological response to treatment, realistic goals of orthodontics can be mutually recognized and agreed on by both the provider and the patient before therapy is initiated.

Condylar movement and mandibular rotation during jaw opening.

Inaccurate description of mandibular rotation can have profound effects on orthognathic surgical treatment planning and surgical outcome, as well as affect the precision of appliances fabricated on articulators. Disagreement exists concerning movements of the condyle during jaw opening. Although mandibular function is often described as rotation around an instantaneous center located outside of the condyle, many believe that jaw opening occurs around an axis of rotation that remains fixed at the center of the condylar head. In this study, condylar movements and centers of mandibular rotation during jaw opening were examined in normal subjects with the Dolphin Sonic Digitizing System. All of the subjects demonstrated both translation and rotation of the condyle during initiation of jaw opening, and none had a center of mandibular rotation located at the condylar head. The findings support the theory of a constantly moving, instantaneous center of jaw rotation during opening that is different in every person. There were also differences in movement within the subjects between experimental trials. The uncertainty of predicting mandibular rotation for a given patient should be considered when planning surgical treatment and fabricating orthodontic appliances.

The ground rules for arch wire design.

All force systems applied to a tooth are composed of either single forces and/or couples. The application of a force through the center of resistance of a tooth will result in translation of the tooth. The application of a force to act at points other than through the center of resistance of a tooth will produce different tendencies for rotation. Tooth rotation resulting from the application of a force always creates a simultaneous tendency to move the center of resistance of a tooth in the direction the force is acting. In contrast, the location of a couple on a tooth is irrelevant to the resulting tooth movement. A couple can never move the center of resistance, and with a couple the center of rotation and the center of resistance will always be coincident. The equilibrium forces, associated with a moment of a couple, also are single-point forces and can produce different tooth movements depending on where they are applied. All tooth movement must be either translation and/or rotation as defined at the tooth's center of resistance.

One-couple orthodontic appliance systems.

One-couple orthodontic appliances are capable of applying well-defined forces and couples to effect controlled tooth movement during treatment. There are two sites of attachment: one in which the appliance is inserted into a bracket or tube where both a couple and force is generated, and one at which the appliance is tied as a point contact where only a force is produced. Using relatively simple designs, powerful biomechanical force systems that are easy to discern clinically can be applied to move teeth according to a prescribed plan. Several one-couple appliances are described to move individual or groups of teeth in all three dimensions. A complete biomechanical analysis of each appliance is presented and clinical reports follow each description.