Brian Nebbe

CEPHALOMETRIC LANDMARKS IDENTIFICATION AND REPRODUCIBILITY : A META ANALYSIS

To assess the magnitude of cephalometric landmarks identification error, we performed a Meta analysis on six pertinent studies. We outline the procedures used to compare and integrate the findings of these-studies. The results are a measure of systematic and random errors involved when locating landmarks on lateral head films. They are presented as standard mean errors and 95% confidence intervals for the repeatability and reproducibility of 15 cephalometric landmarks commonly used in growth analysis.

Use of Skeletal Maturation Based on Hand-Wrist Radiographic Analysis as a Predictor of Facial Growth: A Systematic Review

The purpose of this systematic review was to evaluate the predictive value of hand-wrist radiographic assessment of skeletal maturity in estimating facial growth timing and velocity. A search of PubMed, Medline, Cochrane Database of Systematic Reviews, Embase, Web of Sciences, and Lilacs identified 16 articles that met the following inclusion criteria: use of hand-wrist radiographs for skeletal maturation determination, facial growth evaluated through cephalometric radiographs, and cross-sectional or longitudinal studies. Five articles were rejected because of major methodological issues. Most of the remaining articles had small sample size, and there was no report of randomization or method error. Skeletal maturity determined by hand-wrist radiographic analysis was well related to overall facial growth velocity. Maxillary and mandibular growth velocities were related to skeletal maturity, but their relationship was less robust than that for overall facial growth. The available articles have not adequately defined a relationship between cranial base growth velocity and skeletal maturity. Hand-wrist radiographic assessment of skeletal maturity for use in facial growth prediction should include bone staging as well as ossification events. The role of skeletal maturity assessment in clinical and research applications is discussed and recommendations are provided.

Craniofacial asymmetry and temporomandibular joint internal derangement in female adolescents: a posteroanterior cephalometric study.

Unilateral or bilateral pathology of the osseous components of the temporomandibular joint (TMJ) can result in pronounced facial asymmetry because of dissimilar size and shape of the right and left sides of the mandible. To date, it is unknown whether abnormalities of the soft tissues of the TMJ are associated with greater than normal craniofacial asymmetry. In this study, we investigated the amount of craniofacial asymmetry in female orthodontic patients with unilateral or bilateral TMJ internal derangement (TMJ ID) relative to the amount in female patients without TMJ ID. The total sample consisted of 80 female adolescents. Bilateral TMJ magnetic resonance images were used as a database for objectively scoring the severity of TMJ ID. Craniofacial asymmetry was measured from posteroanterior cephalograms. Females with bilateral TMJ ID had significantly greater asymmetry in the vertical position of the antegonion. If the TMJ ID was more advanced on the right side, the ipsilateral ramus was shorter, resulting in significant asymmetry in this region. In all other craniofacial regions, the amount of asymmetry was not significant between females with normal TMJs and those with TMJ ID. The results indicate that a female orthodontic patient with bilateral TMJ ID or unilateral right TMJ ID may present with or develop a vertical mandibular discrepancy.

Use and effectiveness of splint appliance therapy: review of literature.

Interocclusal orthopedic appliances of varied design and application have been employed in the treatment of myofascial pain dysfunction (MPD) and temporomandibular joint disorders (TMD). These appliances provide the practitioner with a non-invasive, reversible form of intervention to manage the patients symptoms. Literature on the use and effectiveness of these appliances has become readily available and now requires retrospective evaluation. However, comparison of results from studies making use of interocclusal orthopedic appliance therapy is difficult due to the employment of various outcome measurement scales, subjective evaluation of patient outcome, and variability in reporting of treatment outcomes. The aim of this paper is to review the effects and success rates of the various appliances reported in the literature and provide the practitioner with useful information that may be of assistance in the prediction of outcome and success of splint appliance therapy.

Quantitative assessment of temporomandibular joint disk status

The purpose of this study was to quantify temporomandibular joint disk-slice information produced by magnetic resonance imaging by means of a stepwise discriminant analysis. One hundred ninety-four adolescents consented to magnetic resonance imaging evaluation of their temporomandibular joints. Sagittal magnetic resonance imaging slices of each joint were assigned to one of six subjective categories of disk position by an experienced maxillofacial radiologist. Standardized reference planes transferred to each magnetic resonance image from corresponding lateral cephalometric radiographics facilitated the measurement of disk length and disk displacement and the computation of ratio values of these measurements. Discriminant analysis revealed that all three quantitative variables were descriptive and discriminant for grouping slice data into pre-established subjective categories. Cross-validation and misclassification error calculations showed a 69.3% agreement between subjective and discriminant classification. Therefore quantification of disk displacement can be used in place of subjective evaluation. In addition, discriminant analysis disclosed a reduction in disk length associated with increased severity of disk displacement.

Orthodontic brackets bonded to glazed and deglazed porcelain surfaces.

Edgewise orthodontic brackets were bonded with a light activated composite resin to 100 glazed and 100 deglazed feldspathic porcelain blocks for an in vitro comparative determination of shear/peel bond strengths. The independent variables studied were porcelain surface preparation and the time interval between activation of the composite resin and the debonding procedure. The initial shear/peel bond strength achieved on bonding to deglazed porcelain was statistically significantly greater than that on bonding to glazed porcelain (p<0.05), but after the 10-minute interval, the bond strength in the glazed porcelain sample was greater than in the deglazed sample. Many more porcelain fractures occurred on deglazed porcelain (71%) than on glazed porcelain (36%) during bond strength determination. Scanning electron microscopy evaluation suggests that deglazing does not substantially increase micromechanical adhesion of the composite resin. Bond strength adequate to withstand the application of orthodontic forces were achieved when bonding to glazed porcelain. This study indicates that deglazing may not be necessary for attachment of orthodontic brackets to porcelain surfaces.

TMJ internal derangement and adolescent craniofacial morphology: A pilot study

Intrinsic and extrinsic factors influence the growth of mandibular condylar cartilage. Local environmental factors, such as temporomandibular disc displacement, may alter condylar cartilage growth resulting in facial changes. The aim of this study was to determine if there was an association between identifiable altered craniofacial morphology and disc displacement. Magnetic resonance imaging (MRI) was employed to determine disc position in 25 preorthodontic adolescent patients (mean age 12.8 years, range 10 to 17 years). Magnetic resonance imaging and lateral cephalometric radiography were performed with the teeth held in centric occlusion by means of a polyvinylsiloxane bite registration. Radiographs were traced and variability between tracings within patients was insignificant for all variables (p > 0.04) except Co-Go, S-Go, and SN/Go-Me (p < 0.01). For each patient, 10 linear, 4 angular, and 3 ratio measurements were compared with an age- and sex-matched population in the Craniofacial Growth Series. Multiple regression analysis showed positive and negative associations between disc displacement and cephalometric variables. R-square value was .91 for the left TMJ and .82 for the right. Disc displacement in an adolescent population may be associated with altered craniofacial morphology.

Osseous Morphology and Spatial Relationships of the Temporomandibular Joint: Comparisons of Normal and Anterior Disc Positions

The objective of this study was to determine differences in spatial relationships and osseous morphology between temporomandibular joints with normal and anterior disc positions. Magnetic resonance imaging was employed to determine disc position in 335 temporomandibular joints in 175 subjects (106 female and 69 male) between the ages of 7.27 years and 20.0 years (mean age: 13.08 years). Twelve tomographic variables were measured from preorthodontic tomograms of the same individuals. Tomographic data were cross-referenced with MRI data for those with normal and full anterior disc displacement. Independent sample t-tests revealed significant differences for all measures of joint space, condylar position, and morphology of the articular eminence (P < .05) between joints with normal disc position and with full anterior disc displacement. This study indicated that measures of joint space and eminence morphology might provide diagnostic information for the assessment of joint status in the adolescent population.

Interobserver reliability in quantitative MRI assessment of temporomandibular joint disk status

OBJECTIVE The purpose of this study was to investigate interobserver reliability of a new technique for quantification of magnetic resonance images of temporomandibular joint disk status. STUDY DESIGN Sixty magnetic resonance images of adolescent temporomandibular joints were randomly drawn for analysis. Four experienced observers traced the articular disk and osseous structures on sagittal magnetic resonance slice images. Quantitative measurements of disk length and disk displacement were recorded for each slice of 57 joints traced by each observer through use of a new quantification technique. Intraclass correlation coefficients were computed to assess interobserver agreement in the tracing of joint structures. RESULTS The calculated intraclass correlation coefficient was 0.681 for disk length and 0.830 for disk displacement. In addition, the mean variability among observers was 1.041 mm for measurement of disk length and 0.972 mm for measurement of disk displacement. CONCLUSIONS Interobserver agreement is high when the new quantification technique is used to interpret magnetic resonance images.

Short-term treatment effects produced by the Twin-block appliance: a systematic review and meta-analysis

OBJECTIVE To evaluate dental, skeletal, and soft tissue effects during Twin-block treatment. METHODS A systematic search of several electronic databases (Medline, PubMed, Embase, all EBM reviews, and Web of Science) was conducted until July 2013, as well as a limited grey-literature search (Google Scholar). Human cephalometric studies that used a Twin-block appliance in a non-extraction and non-surgical approach were selected. A comparable control group of untreated subjects was required. Two authors independently reviewed and extracted data from the selected studies. Risk of bias was assessed. The type of meta-analysis was selected based on heterogeneity. RESULTS Ultimately 10 articles were included. Proclination of lower incisors, retroclination of upper incisors, distal movement of upper molars and/or mesial movement of lower molars, increase in mandibular length, and/or forward movement of the mandible were consistently reported. Clinically significant restraint of maxillary growth was not found. Although the mandibular body length is increased, the facial impact of it is reduced by the simultaneous increment of the face height. Changes of lower face height and occlusal plane inclination varied, suggesting that vertical dimension can be manipulated in patients who would benefit from lower molar extrusion. As for lip position, there is not enough evidence to suggest clear lip position changes. CONCLUSIONS Changes associated with a Class II correction were identified. Most of the changes individually were of limited clinical significance, but when combined reached clinical importance. No long-term changes were available.