Computed tomography assessment of hypodontia and crown size in hemifacial microsomia.

OBJECTIVE: Our aims were to assess the prevalence of hypodontia in unilateral hemifacial microsomia (HFM), and to compare tooth (crown) size between affected and unaffected sides. DESIGN: In a retrospective cross-sectional study of South Australians, computed tomography (CT) scans were used to assess hypodontia and crown size (mesiodistal length, buccolingual width and crown height). The inclusion criteria were the absence of other congenital anomalies and the availability of CT scans. The exclusion criteria were the lack of extraction history or reproducible landmarks for morphometric assessment. The final sample comprised 41 participants in both dentitions, including 32 children and 9 adults (median age 13.9 years, range 0.4 - 47.6 years; 19 males and 22 females). Hypodontia was assessed in all participants, and the permanent crown size in 30 (73.2%) participants. Linear mixed-effects models were performed to determine if crown size was significantly different between the two sides, controlling for sex, HFM severity, and tooth and jaw type. RESULTS: Hypodontia occurred in none of the participants in the primary dentition, but in 6/30 (20%) participants in the permanent dentition (3/30 each on the affected and unaffected sides). There was no significant difference in the mean crown dimensions between the two sides, but the crown size was larger in males (p < 0.05), except for mesiodistal length, and became progressively smaller with increased HFM severity (p < 0.05). CONCLUSIONS: Hypodontia spared the primary dentition but featured prominently in the permanent dentition. The permanent crown dimensions were unaltered between the two sides.

An accurate and efficient method for occlusal tooth wear assessment using 3D digital dental models.

Tooth or material wear in a dentition is a common finding that requires timely diagnosis for management and prevention of further loss or associated esthetic or functional impairment. Various qualitative and quantitative methods have been suggested to measure tooth or material wear, but they present with limitations, such as imprecision, subjectivity, or high complexity. Here we developed and assessed an efficient 3D superimposition method to accurately measure occlusal tooth wear on 3D digital dental models. For this purpose, teeth on plaster casts were manually grinded on their occlusal surfaces to simulate various degrees of tooth wear. The casts were scanned using a surface scanner. Grinded tooth crowns (T1) were segmented and compared to the original crowns (T0) using five 3D surface superimposition techniques and a gold standard technique (GS). GS measurements were obtained by using intact adjacent structures as superimposition references. The technique of choice (complete crown with 30% estimated overlap of meshes) showed the best reproducibility (maximum difference < 0.050 mm3) and excellent agreement with the GS technique (median difference: 0.032 mm3). The suggested 3D superimposition method offers a highly efficient and accurate tool for tooth wear assessment, which could be applicable to clinical conditions.

Volumetric assessment of the dental crown for sex estimation by means of cone-beam computed tomography.

Sex estimation has a vital role in the solution of forensic cases when the identification of a large number of victims is needed. Considering the sexual dimorphism of the human teeth, the objective of this study was to estimate human sex by means of cone beam computed tomography (CBCT)-based volumetric assessment of the dental crown. A total of 78 CBCT images of the upper central incisors, upper and lower canines, and lower lateral incisors were equally selected from a Brazilian population aged between 8 and 36 years old. The dental crowns were subjected to image-based volumetric assessment by manual segmentation using the 3D slicer software, and the outcomes were compared by the Mann-Whitney test, unpaired t-test, Pearson correlation test, conditional backward stepwise logistic regression and intraclass correlation coefficient (α=0.05). The volumetric accuracy of the upper central incisor, upper canine and lower canine for sex estimation were 64.1%, 74.4% and 79.5%, respectively. The combined analysis of the upper and lower canines allowed an average accuracy of 83.7%. In conclusion, the combined volumetric analysis of the crown of the upper and lower canines can be applied for sex estimation in the studied population.

Radiographic assessment of the relationship between root canal treatment quality, coronal restoration quality, and periapical status.

OBJECTIVE: The aim of this cross-sectional study was to assess the prevalence of apical periodontitis in root canal treated teeth in Turkish subpopulation and to evaluate the effects of both coronal restoration quality and root canal treatment (RCT) quality on apical periodontitis. MATERIALS AND METHODS: Panoramic images of individuals who applied to our department for different diagnostic reasons were randomly and retrospectively scanned. Total RCT number, RCT quality, type of coronal restoration, restoration quality, periapical status, and total number of teeth were recorded. The criteria used for coronal restorations quality and RCT quality were defined by De Moor et al. and slightly modified by Gunduz et al. Periapical status was assessed by the periapical index developed by Orstavik et al. Pearson's Chi-square test was used for statistical analysis, and the intraobserver agreements were assessed by Kappa coefficients. Values of P < 0.05 were accepted to be meaningful. RESULTS: The total examined teeth number was 6064, of which had 541 (8.9%) RCT. The prevelance of apical periodontitis was 40.5%. The number of adequate RCT was 178 (32.9%), and 138 (77.5%) of them were healthy. The number of adequate coronal restoration was 334, and 62.3% of them were healthy. For the cases that have adequate coronal restorations, there was statistically significant relationship between adequate RCT and periapical status (P < 0.001). CONCLUSION: The prevelance of apical periodontitis was 40.5% and there was statistically significant relationship between adequate RCT and periapical status.

Assessment of Periodontal Biotype in a Young Chinese Population using Different Measurement Methods.

Periodontal biotype is used to describe the morphological characteristics of periodontal tissues and is closely related to periodontal health and prognosis of many dental treatments. This study was undertaken to explore the periodontal biotype distribution in a young Chinese population and to evaluate the accuracy of different methods for gingival thickness (GT) measurement. A total of 372 teeth from 31 periodontally healthy subjects were included. GT was measured simultaneously by probe transparency, transgingival probing and cone-beam computed tomography (CBCT). Some other anatomic parameters, including crown width/crown length ratio, attached gingival width, labial bone thickness and papilla volume were recorded for periodontal biotype classification. As found by probe transparency, the gingivae of 222 teeth (59.68%) were thick, while those of 150 teeth (40.32%) were thin. The mean GT of included subjects was 1.03 ± 0.31 mm as measured by transgingival probing and 1.03 ± 0.24 mm as measured by CBCT. Four groups were identified by cluster analysis. Thick-flap biotype, average-scalloped biotype, average-flap biotype and thin-scalloped biotype comprised 137 teeth (36.83%), 96 teeth (25.81%), 39 teeth (10.48%) and 100 teeth (26.88%), respectively. These results demonstrate that the most common periodontal biotype in this young Chinese population was the thick-flap type with low aesthetic risk.

A comparison of the use of cone-beam computed tomography and panoramic radiography in the assessment of pre-eruptive intracoronal resorption.

OBJECTIVE: This study aimed to investigate the prevalence of pre-eruptive intracoronal resorption (PIR) using cone beam computed tomography (CBCT) and panoramic radiography and to compare the findings of these imaging techniques. METHODS: This retrospective study consisted of 733 patients who had at least one unerupted tooth and had undergoneimaging with both three-dimensional (3D) CBCT and two-dimensional (2D) panoramic radiography. In all the images, the number of teeth with intracoronal resorption, affected tooth type and number, and size and location of the PIR defects were recorded. The McNemar test was used to compare the prevalence of PIR in the CBCT and panoramic images. RESULTS: Fewer PIR defects were detected in the panoramic images (3.1% of the patients) than in the CBCT images (9.5% of the patients) (p< .001). According to the CBCT images, the distribution of PIR defects was as follows: third molars (59.5%), canine teeth (11.4%), second molars and premolars (7.6% for both), supernumerary teeth (5.1%), second molars (3.8%), central incisors (2.5%), and first premolar and primary second molar teeth (1.5% for both). According to the scoring classification system for PIR defects, PIR 1 defects were the most common (65.8%), followed by PIR 3 (24.1%) and PIR 2 (10.1%). Of these defects, 69.6% were located in the central aspect of the crown. Ectopically positioned teeth showing intracoronal resorption accounted for 51.9% of the cases of PIR. CONCLUSIONS: CBCT detected more cases of PIR than panoramic radiography. The mandibular third permanent molar was the most commonly affected tooth.

Effectiveness of Air Drying and Magnification Methods for Detecting Initial Caries on Occlusal Surfaces Using Three Different Diagnostic Aids.

Objective-The aim of this study was to assess the effect of magnification and air-drying on detection of carious lesion. Study Design-44 human extracted premolars were selected with sound occlusal surfaces without frank cavitation. The Diagnostic techniques used were Unaided visual examination, Magnifying Loupes (4.2×) and Stereomicroscope (10×, before and after air-drying) and then the teeth were sectioned bucco-lingually and both the surfaces were examined under Stereomicroscope (50×) to assess the presence or absence of carious lesion in the pit and fissures. The scores were compared to obtain Cohen's kappa coefficient (Reproducibility) and subjected to the Friedman Test and Paired t test. Sensitivity, specificity and positive predictive value used to assess accuracy. Results-On Statistical analysis, visual examination before and after air drying had highest specificity but lowest sensitivity compared to different diagnostic techniques. Magnifying loupes after air-drying had highest sensitivity and lowest specificity compared to other diagnostic techniques. Conclusion-Air drying combined with magnifying aids are cost-effective, reliable method for detection of early carious lesion. If used in pediatric clinical practice, any undesirable pain and discomfort to the patient due to invasive procedures and helps in employing preventive measures.

In Vitro Assessment of Enamel Permeability in Primary Teeth with and without Early Childhood Caries Using Laser Scanning Confocal Microscope.

OBJECTIVE: To compare the permeability of the enamel of primary teeth from individuals free of Early Childhood Caries (ECC) with that from individuals affected with ECC by assessment of dye penetration using Laser Scanning Confocal Microscope (LSCM). STUDY DESIGN: Experimental in vitro study. Exfoliated primary maxillary anterior teeth (n = 44) were collected and divided into two groups (n=22 per group): samples with ECC (Group 1) and without ECC (Group 2). The samples were immersed in Rhodamine B dye solution for 1 day, cut longitudinally into 3 sections, observed using LSCM. Dye penetration depths in the incisal, middle, cervical thirds and on labial, lingual surfaces were recorded. Data were analyzed by the Mann-Whitney test (α = 5%, p < .005). RESULTS: The overall mean penetration depth for group 1 (100.6 µm ± 58.48 µm) was significantly higher than that of group 2 (31.55 µm ± 23.40 µm, p < .000). Mean penetration depth in the incisal, middle, and cervical thirds and on the labial and lingual surfaces of group 1 also presented significantly higher scores than in group 2 (p < .005). CONCLUSION: There was significantly more dye penetration in the ECC group than in the non-ECC group. This could be related to a higher level of enamel permeability in teeth affected with ECC.

A Clinical and Radiographic Assessment of Positional Variations of Gingival Papilla and Its Proportions.

In 60 healthy subjects, 720 interdental papilla sites in maxillary anterior teeth were investigated. Interdental papilla heights were measured from the gingival zenith along the clinical crown lengths. Radiovisiography was used to measure the relative bone length. Percentage of papilla height to crown length and radiographic bone length to crown length were computed and defined as papilla proportion (PP) and crestal papilla proportion (cPP), respectively. The overall mean mesial PP was 44.95 ± 6.80% and distal PP was 45.70 ± 7.87%. The total mean mesial cPP was 54.12 ± 9.50% and distal cPP was 54.95 ± 9.28%. Taken together, the cPP was around 55% and the PP was around 45% for all tooth groups.

Radiographic assessment of lower third molar eruption in different anteroposterior skeletal patterns and age-related groups.

OBJECTIVE: To analyze radiographic predictors for lower third molar eruption among subjects with different anteroposterior skeletal relations and of different age groups. MATERIALS AND METHODS: In total, 300 lower third molars were recorded on diagnostic digital orthopantomograms (DPTs) and lateral cephalograms (LCs). The radiographs were grouped according to sagittal intermaxillary angle (ANB), subject age, and level of lower third molar eruption. The DPT was used to analyze retromolar space, mesiodistal crown width, space/width ratio, third and second molar angulation (α, γ), third molar inclination (ß), and gonion angle. The LC was used to determine ANB, angles of maxillar and mandibular prognathism (SNA, SNB), mandibular plane angle (SN/MP), and mandibular lengths. A logistic regression model was created using the statistically significant predictors. RESULTS: The logistic regression analysis revealed a statistically significant impact of ß angle and distance between gonion and gnathion (Go-Gn) on the level of lower third molar eruption (P < .001 and P < .015, respectively). The retromolar space was significantly increased in the adult subgroup for all skeletal classes. The lower third molar impaction rate was significantly higher in the adult subgroup with the Class II (62.3%) compared with Class III subjects (31.7%; P < .013). CONCLUSION: The most favorable values of linear and angular predictors of mandibular third molar eruption were measured in Class III subjects. For valid estimation of mandibular third molar eruption, certain linear and angular measures (ß angle, Go-Gn), as well as the size of the retromolar space, need to be considered.

An in vivo comparison of radiographic and clinical examination with separation for assessment of approximal caries in primary teeth.

AIM: To compare in vivo, clinical examination (CE) and bitewing radiographs (BW) for the detection of cavitations and initial approximal lesions in deciduous molars with validation after temporary separation (TS) and direct visual examination (DE) of the approximal surfaces. MATERIALS AND METHODS: Thirty children aged 4 to 8 years without visual cavitations or restorations and with at least one approximal contact. Two calibrated examiners evaluated 355 surfaces of primary molars, which were then validated through TS and DE. RESULTS: Of the 280 surfaces considered sound by CE, 24.6% were cavitated after separation. Comparing BW and DE, it was observed that, when the radiolucency involved the inner half of dentin, 68.4% of lesions were cavitated. The sensitivity and specificity of CE and BW were 0.14 and 0.43, and 0.80 and 0.75, respectively. CONCLUSION: DE identified a greater number of pre-cavitated lesions and cavities. BW were useful for detection of decayed surfaces, but with low specificity for diagnosis of sound surfaces, while detection of sound or decayed approximal areas by means of CE alone was not possible. The combination of methods was effective in obtaining an accurate diagnosis of caries in the primary dentition.

Cone-beam computed tomography for assessment of palatal displaced canine position: a methodological study.

OBJECTIVE: To assess the inter- and intraexaminer reliability of a measurement method for evaluation of eruption angles and position of palatal displaced canines (PDCs) with cone-beam computed tomography (CBCT) images and to test the validity of the measured angles on a dry skull. MATERIALS AND METHODS: Twenty patients (eight boys, 12 girls; age 11.4±1.2 years) were randomly chosen among 67 patients from a study evaluating the interceptive effect of extracting the deciduous canine in children with PDCs. In total, 60 images were analyzed, because each patient had three CBCT examinations (baseline, 6-month control, and endpoint). Two observers assessed the following measurements twice: mesioangular and sagittal angle, vertical position, canine cusp tip, and canine apex to dental arch. The validity of the angular measurements was tested against angular measurements on a dry skull using mathematical formulations. RESULTS: The inter- and intraexaminer mean differences for angular and linear measurements were all low and statistically insignificant (P>.05). The mean differences between the physical and 3D measurements were 0.5±0.39 mm for the sagittal angle and 0.22±0.19 mm for the mesioangular angle. CONCLUSIONS: Linear and angular measurements on CBCT images are accurate and precise and can be used to assess the precise position of a PDC.

Tooth mineralization stages as a diagnostic tool for assessment of skeletal maturity.

INTRODUCTION: The objective of this study was to determine whether dental calcification can be used as a first-level diagnostic tool for assessment of skeletal maturity. METHODS: A total of 150 healthy subjects (79 boys, 71 girls; mean age, 12.19 ± 2.03 years; range, 8-16 years) were enrolled in the study. Dental maturity was assessed through the calcification stages from panoramic radiographs of the mandibular canine, the first and second premolars, and the second molar. Determination of skeletal maturity was according to the modified middle phalanx of third finger (MP3) stages method on digital radiographs. RESULTS: Diagnostic ability was evaluated according to the dental maturation stages for each tooth for identification of the MP3 stages and the growth phases (prepubertal, pubertal, postpubertal) using positive likelihood ratios. Dental maturation stage E of the first premolars and the combination of canine stage F, first premolar stage E, second premolar stage E, and second molar stage D (FEED) gave the highest values for identification of the prepubertal growth phase, and stage H of the second molar had the highest value for identification of the postpubertal growth phase. CONCLUSIONS: Dental maturation assessment is only useful for diagnosis of the prepubertal and postpubertal growth phases.

Assessment of factors associated with surgical difficulty during removal of impacted maxillary third molars.

PURPOSE: Estimating the difficulty of removing third molars is a common dilemma. However, the estimation of the difficulty associated with maxillary third molar surgery has not yet been defined. The aim of the present study was to determine the degree of difficulty and identify predictor variables associated with the occurrence of difficulty in the removal of impacted maxillary third molars. MATERIALS AND METHODS: A prospective cohort study was carried out involving patients who underwent at least 1 surgical removal of an impacted maxillary third molar at the Oral and Maxillofacial Surgery Unit, University of Pernambuco (Pernambuco, Brazil). Predictor variables indicative of surgical difficulty were classified by their demographic, clinical, and radiographic aspects. Degree of surgical difficulty was categorized as low, moderate, or high based on the surgical technique used. Descriptive and bivariate statistics were computed. RESULTS: In total, 106 patients fulfilled the eligibility criteria and 204 surgeries were performed. Patients' mean age was 22.8 ± 2.2 years and the proportion of women to men was 3:1. Approximately 20% of patients were overweight. Surgical difficulty was generally low and 5 variables were significantly associated with the occurrence of a high degree of surgical difficulty. CONCLUSION: Surgical difficulty during the removal of impacted maxillary third molars is generally low. However, for cases with a high degree of difficulty, identification of predictor variables may be useful for students and inexperienced clinicians to consider the decision not to execute the procedure, thus avoiding complications that often require complex management.

Assessment of factors associated with surgical difficulty during removal of impacted lower third molars.

PURPOSE: The aim of the present study was to adjust a multivariate model to explain each of the response variables for the occurrence of surgical difficulty during the removal of impacted lower third molars. PATIENTS AND METHODS: A prospective cohort study was carried out involving patients submitted to at least one surgical removal of an impacted lower third molar. A total of 285 patients fulfilled the eligibility criteria and 473 surgeries were performed. Preoperative variables indicative of surgical difficulty were recorded. All surgical procedures were performed under the same conditions by two surgeons who were unaware of the data collected in the pre-selection phase. Either Pearson's chi-square test or Fisher's exact test was used for the data analysis (P<5.0%). RESULTS: Root number (P((1)) < 0.004*) and morphology (P((1)) < 0.031*), tooth position (P((1)) = 0.001*), periodontal space (P((2)) < 0.004*) and second molar relation (P((1)) = 0.001*) were significant predictors of surgical difficulty, whereas patient age (P((1)) = 0.097), gender (P((1)) = 0.470), body mass index (P((1)) = 0.719), associated pathologies (P((1)) = 0.237), relation with mandibular canal (P((1)) = 0.384) and width of 3rd molar crown (P((1)) = 0.154) were not significant predictors. CONCLUSION: Many factors contribute to surgical difficulty, but considering these factors individually, some are only determinants of either difficulty or complications. Thus, not all significant predictors of surgical difficulty should be considered indicators of complications.

Age assessment by the Greulich and Pyle method compared to other skeletal X-ray and dental methods in data from Finnish child victims of the Southeast Asian Tsunami.

The validity of the age assessment method based on the "Radiographic Atlas of Skeletal Development of the Hand and Wrist" by Greulich and Pyle (1st edition 1950) has been frequently questioned. The purpose of this study was to examine the reliability of this widely used method and to compare it to various dental and other skeletal age assessment methods. Forty-seven Finnish children of known ages below 16 years, who perished in Thailand in the Southeast Asian Tsunami on 26 December 2004 were examined. Every victim repatriated to Finland underwent a complete forensic autopsy including CT-scan, toxicological screening, and diatom analysis in order to establish the cause of death, as well as DNA testing and dental examination for the verification of the identification established in Thailand. Age assessment was performed by dental and skeletal methods. The average difference between the age assessment values obtained by the Greulich and Pyle method, and the chronological age was 9.7 months. In addition to the Greulich and Pyle method, an alternate skeletal method, Tanner and Whitehouse 2, resulted in an average age difference of 10.3 months. Dental age assessment methods were based either on the eruption (Nyström method, 8 cases, average age difference 5.6 months), or the development of the crown and roots (Demirjian method, 33 cases, average age difference 5.2 months and ABFO method, 7 cases, average differences 12.6 months). Dental methods proved to be most accurate in childhood until the teeth-with the exception of wisdom teeth-have erupted and root development is completed. In adolescence, however, the validity of skeletal methods improves considerably.

Distortional effect of beam-hardening artefacts on microCT: a simulation study based on an in vitro caries model.

OBJECTIVE: The aim of this study was to assess quantitatively the degrading effect of artefacts caused by beam hardening on the microscopic computerized tomography (microCT) measurements of an in vitro caries model. STUDY DESIGN: A simulation-based method was described, with which the degrading effect of microCT artefacts on certain parameters of the observed structure could be determined. Simulations were carried out with polychromatic and monochromatic X-ray source, and a linearization method with a second-order polynomial fit algorithm was used in specific cases to correct the beam hardening artefact. The virtual test object was a half-crown of a tooth with an artificial caries lesion. RESULTS: For simulation with monochromatic X-ray source, the relative error of lesion depth and thickness measurements of the remineralized layer was found to be 1%-2%. For polychromatic X-ray source, and omitting beam hardening correction, the relative error exceeded 6%. After appropriate beam-hardening correction, the relative error of the measurement could be reduced to 1%-2%. CONCLUSION: With the adjustment simulated in this study, microCT having polychromatic X-ray source resulted in the same level of error as with monochromatic source if the linearization method to correct the beam hardening was used. The presented simulation-based method is a useful way to determine artefact-caused distortions for other studies testing objects with different material and geometry.

Topographic and radiographic profile assessment of dental erosion. Part II: effect of citrus fruit juices on human dentition.

This study sought to monitor changes in the topography, morphology, and radiographic profiles of human permanent teeth that had been exposed to citrus fruit juices. The effect of long-term exposure was monitored for a prolonged duration of 20 weeks according to set criteria. Topographic and morphologic changes were observed at weekly intervals following challenge by test fluids (orange, lemon, and grapefruit juices) and compared with control fluids (acetic acid and water). The qualitative changes in the specimens' topography and the morphology of citrus fruit juices and control fluids are described as a function of time, in specific details. The digitized radiographic images obtained at four-week intervals were analyzed and the changes were assessed. The results indicated that orange juice specimens demonstrated the mildest changes, while lemon juice specimens displayed the most severe damage to the coronal segments of the teeth. This damage manifested as loss of cusp height, cervical enamel, and coronal radius, as well as reduction of enamel cap height. Of the tested and control fluids, lemon juice displayed the most eros ion, followed by acetic acid, grapefruit juice, orange juice, and water, which had no effect. Continued immersion in the four acidic fluids led to varying degrees of enamel loss progression.