Paul W. Major

Three-dimensional accuracy of measurements made with software on cone-beam computed tomography images.

INTRODUCTION The purpose of this article was to evaluate the accuracy of measurements made on 9- and 12-in cone-beam computed tomography (CBCT) images compared with measurements made on a coordinate measuring machine (CMM), which is the gold standard. METHODS Ten markers were placed on a synthetic mandible, and landmark coordinates and linear and angular measurements were determined with the CMM. Three-dimensional CBCT images, measuring 9 and 12 in, were taken of the mandible with a CBCT machine (NewTom 3G, Aperio Services, Verona, Italy), and landmark coordinates and linear and angular measurements were obtained with AMIRA (Mercury Computer Systems, Berlin, Germany) software. RESULTS The coordinate intrareliability correlation coefficient was almost perfect between the 3-dimensional CBCT images and the CMM measurements. With the Student t test, we found no significant statistical difference between linear and angular measurements from the CMM and the NewTom 3G images, which differed less than 1 mm and 1 degrees , respectively. CONCLUSIONS The NewTom 3G produces a 1-to-1 image-to-reality ratio.

Lay person’s perception of smile aesthetics in dental and facial views

Objective To compare the aesthetic perception of different anterior visible occlusions in different facial and dental views (frontal view, lower facial third view and dental view) by lay persons. Design Cross-sectional survey, Lima, Perú, 2002. Subjects The different views were rated by 91 randomly selected adult lay persons. Main outcome measurement Visual Analogue Scale (VAS) ratings of aesthetic perception of the views. Results Anterior visible occlusion, photographed subject and view (p<0.001) had a significant effect on the aesthetic ratings. Also gender (p=0.001) and the interaction between gender and level of education (p=0.046) had a significant effect over the aesthetic rating. Conclusions A lay panel perceived that the aesthetic impact of the visible anterior occlusion was greater in a dental view compared with a full facial view. The anterior visible occlusion, photographed subject, view type are factors, which influence the aesthetic perception of smiles. In addition, gender and level of education had an influence.

Long-term Skeletal Changes with Rapid Maxillary Expansion: A Systematic Review

The objective was to evaluate long-term transverse, anteroposterior and vertical skeletal changes after rapid maxillary expansion (RME). The data were clinical trials that assessed skeletal changes through cephalometric analysis. No surgical or other simultaneous treatment during the evaluation period was accepted. Electronic databases (PubMed, Medline, Medline In-Process & Other Non-Indexed Citations, Cochrane Database of Systematic Reviews, ASP Journal Club, DARE, CCTR, Embase, Web of Sciences and Lilacs) were searched with the help of a senior Health Sciences librarian. Abstracts that appeared to fulfill the initial selection criteria were selected by consensus. The original articles were then retrieved. A methodological checklist was used to evaluate the quality of the selected articles. Their references were also hand-searched for possible missing articles. Articles without an adequate control group to factor out growth changes were excluded. Only three articles (one measuring transverse and two anteroposterior and vertical changes) measured RME stability after active expansion, all of them had some methodological flaws, which limit the attainable conclusions. An individual analysis of these articles was made. Long-term transverse skeletal maxillary increase is approximately 25% of the total dental expansion for prepubertal adolescents. Better long-term outcomes are expected in transverse changes because of RME in less skeletally mature patients. RME appears not to produce clinically significant anteroposterior or vertical changes in the position of the maxilla and mandible. The conclusions from this systematic review should be considered with caution because only a secondary level of evidence was found. Long-term randomized clinical trials are needed.

Landmark identification error in posterior anterior cephalometrics.

This study was designed to quantify the intraexaminer and interexaminer reliability of 52 commonly used posterior anterior cephalometric landmarks. The horizontal and vertical identification errors were determined for a sample of 33 skulls and 25 patients. The results show that there is a considerable range in the magnitude of error with different horizontal and vertical values. Interexaminer landmark identification error was significantly larger than intraexaminer error for many landmarks. The identification error was different for the skull sample compared to the patient sample for a number of landmarks. The relevance of knowing the identification error for each landmark being considered in a particular application was discussed.

Role of different imaging modalities in assessment of temporomandibular joint erosions and osteophytes: a systematic review

OBJECTIVES To evaluate the ability of different diagnostic imaging techniques for diagnosing the presence of erosions and osteophytes in the temporomandibular joint (TMJ). METHODS A systematic search of PubMed, Medline, all Evidence Based Medicine (EBM) reviews, Embase, Web of Sciences and Lilacs identified nine articles that met the selection criteria: some type of TMJ diagnostic imaging, data from autopsy or dry skull TMJs as gold standard, absence of diagnosed systemic arthritis and evaluation of the presence of erosions and/or osteophytes. A hand search of the references of the selected articles was also performed. RESULTS Selected studies evaluated panoramic imaging (unenhanced and colour-enhanced digital subtraction panoramic imaging), axially corrected sagittal tomography, axially corrected frontal tomography, sagittal MRI, CT, high-resolution ultrasound and cone beam CT (CBCT). CONCLUSIONS Axially corrected sagittal tomography is currently the imaging modality of choice for diagnosing erosions and osteophytes in the TMJ. CT does not seem to add any significant information to what is obtained from axially corrected sagittal tomography. CBCT might prove to be a cost- and radiation dose-effective alternative to axially corrected sagittal tomography. Combining different radiographic techniques is likely to be more accurate in diagnosing erosions and osteophytes in the TMJ than using a single imaging modality. Diagnostic studies that simultaneously evaluate all of the available TMJ imaging technologies are needed.

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.

Correlation of Skeletal Maturation Stages Determined by Cervical Vertebrae and Hand-wrist Evaluations

The aim of this study was to assess the correlation between the Fishman maturation prediction method (FMP) and the cervical vertebral maturation (CVM) method for skeletal maturation stage determination. Hand-wrist and lateral cephalograms from 79 subjects (52 females and 27 males) were used. Hand-wrist radiographs were analyzed using the FMP to determine skeletal maturation level (advanced, average, or delayed) and stage (relative position of the individual in the pubertal growth curve). Cervical vertebrae (C2, C3, and C4) outlines obtained from lateral cephalograms were analyzed using the CVM to determine skeletal maturation stage. Intraexaminer reliability (Intraclass correlation coefficient [ICC]) for both methods was calculated from 10 triplicate hand-wrist and lateral cephalograms from the same patients. An ICC coefficient of 0.985 for FMP and an ICC of 0.889 for CVM were obtained. A Spearman correlation value of 0.72 (P < .001) was found between the skeletal maturation stages of both methods. When the sample was subgrouped according to skeletal maturation level, the following correlation values were found: for early mature adolescents 0.73, for average mature adolescents 0.70, and for late mature adolescents 0.87. All these correlation values were statistically different from zero (P < .024). Correlation values between both skeletal maturation methods were moderately high. This may be high enough to use either of the methods indistinctively for research purposes but not for the assessment of individual patients. Skeletal level influences the correlation values and, therefore, it should be considered whenever possible.

Long-term dental arch changes after rapid maxillary expansion treatment: a systematic review

This systematic review evaluates long-term dental arch changes after rapid maxillary expansion treatment on orthodontic patients with constricted arches. Clinical trials that assessed dental arch changes through measurements on dental casts or cephalometric radiographs were selected. No patients with surgical or other simultaneous treatment during the active expansion period were accepted. Electronic databases were searched with the help of a senior Health Sciences librarian. Original articles were retrieved from the selected abstracts, and their references were also scanned for possible missing articles. Forty-one articles met the initial inclusion criteria, but 35 were later rejected because they lacked a control group or only evaluated dental changes or used a semirapid technique. Some of them also lacked a reported measurement error. From the remaining articles, two did not report a long-term evaluation. From the final four articles, two measured changes through dental casts and two assessed changes through radiographs (one through lateral cephalometric radiographs and one through posteroanterior radiographs). Similar maxillary molar and cuspid expansion could be found in adolescents and young adults. Significantly less indirect mandibular molar and cuspid expansion was attained in young adults compared with adolescents. A significant overall gain in the maxillary and mandibular arch perimeter was found in adolescents. More transverse dental arch changes were found after puberty as compared with before, but the difference may not be clinically significant. No anteroposterior dental changes were found on lateral cephalometric radiographs.

Transverse, vertical, and anteroposterior changes from bone-anchored maxillary expansion vs traditional rapid maxillary expansion: A randomized clinical trial

INTRODUCTION The purpose of this study was to compare the transverse, vertical, and anteroposterior skeletal and dental changes in adolescents receiving expansion treatment with tooth-borne and bone-anchored expanders. Immediate and long-term changes were measured on cone-beam computed tomography (CBCT) images. METHODS Sixty-two patients needing maxillary expansion were randomly allocated to 1 of 3 groups: traditional hyrax tooth-borne expander, bone-anchored expander, and control. CBCT images were taken at baseline, immediately after expansion, after removal of the appliance (6 months), and just before fixed bonding (12 months). Repeated measures multivariate analysis of variance (MANOVA) was applied to the distances and angles measured to determine the statistical significance in the immediate and long time periods. Bonferroni post-hoc tests were used to identify significant differences between the treatment groups. RESULTS Immediately after expansion, the subjects in the tooth-borne expander group had significantly more expansion at the crown level of the maxillary first premolars (P = 0.003). Dental crown expansion was greater than apical expansion and skeletal expansion with both appliances. The control group showed little change (growth) over the 6-month interval. At 12 months, no group had a statistically significant difference in angle changes, suggesting symmetric expansion. Both treatment groups had significant long-term expansion at the level of the maxillary first molar crown and root apex, first premolar crown and root, alveolus in the first molar and premolar regions, and central incisor root. Tooth-borne expansion resulted in significantly more long-term expansion at the maxillary premolar crown and root than did bone-borne expansion. CONCLUSIONS Both expanders showed similar results. The greatest changes were seen in the transverse dimension; changes in the vertical and anteroposterior dimensions were negligible. Dental expansion was also greater than skeletal expansion.