A new 3D method for measuring cranio-facial relationships with cone beam computed tomography (CBCT).

OBJECTIVES: CBCT systems, with their high precision 3D reconstructions, 1:1 images and accuracy in locating cephalometric landmarks, allows us to evaluate measurements from craniofacial structures, so enabling us to replace the anthropometric methods or bidimensional methods used until now. The aims are to analyse cranio-facial relationships in a sample of patients who had previously undergone a CBCT and create a new 3D cephalometric method for assessing and measuring patients. STUDY DESIGN: 90 patients who had a CBCT (i-Cat®) as a diagnostic register were selected. 12 cephalometric landmarks on the three spatial planes (X,Y,Z) were defined and 21 linear measurements were established. Using these measurements, 7 triangles were described and analysed. With the sides of the triangles: (CdR-Me-CdL); (FzR-Me-FzL); (GoR-N-GoL); and the Gl-Me distance, the ratios between them were analysed. In addition, 4 triangles in the mandible were measured (body: GoR-DB-Me and GoL-DB-Me and ramus: KrR-CdR-GoR and KrL-CdL-GoL). RESULTS: When analyzing the sides of the CdR-Me-CdL triangle, it was found that the 69.33% of the patients could be considered symmetric. Regarding the ratios between the sides of the following triangles: CdR-Me-CdL, FzR-Me-FzL, GoR-N-GoL and the Gl-Me distance, it was found that almost all ratios were close to 1:1 except between the CdR-CdL side with respect the rest of the sides. With regard to the ratios of the 4 triangles of the mandible, it was found that the most symmetrical relationships were those corresponding to the sides of the body of the mandible and the most asymmetrical ones were those corresponding to the base of such triangles. CONCLUSIONS: A new method for assessing cranio-facial relationships using CBCT has been established. It could be used for diverse purposes including diagnosis and treatment planning.

Study between anb angle and Wits appraisal in cone beam computed tomography (CBCT).

OBJECTIVES: To analyse the ANB and Wits values and to study correlations between those two measurements and other measurements in diagnosing the anteroposterior maxilo-mandibular relationship with CBCT. STUDY DESIGN: Ninety patients who had previously a CBCT (i-CAT®) as a diagnostic register were selected. A 3D cephalometry was designed using one software package, InVivo5®. This cephalometry included 3 planes of reference, 3 angle measurements and 1 linear measurement. The means and standard deviations of the mean of each measurement were assessed. After that, a Pearson's correlation coefficient has been performed to analyse the significance of each relationship. RESULTS: When classifying the sample according to the anteroposterior relationship, the values obtained of ANB (Class I: 53%; Class II: 37%; Class III: 10%) and Wits (Class I: 35%; Class II: 56%; Class III: 9%) did not coincide, except for the Class III group. However, of the patients classified differently (Class I and Class II patients) by ANB and Wits, a high percentage of individuals (n=22; 49%), had a mesofacial pattern with a mandibular plane angle within normal values. A correlation has been found between ANB and Wits (r=0,262), occlusal plane angle and ANB (r=0,426), and mandibular plane angle and Wits (r=0,242). No correlation was found between either Wits or ANB in relation with the age of the individuals. CONCLUSIONS: ANB and Wits must be included in 3D cephalometric analyses as both are necessary to undertake a more accurate diagnosis of the maxillo-mandibular relationship of the patients.

Evaluation of the validity of the Bolton Index using cone-beam computed tomography (CBCT).

AIMS: To evaluate the reliability and reproducibility of calculating the Bolton Index using cone-beam computed tomography (CBCT), and to compare this with measurements obtained using the 2D Digital Method. MATERIAL AND METHODS: Traditional study models were obtained from 50 patients, which were then digitized in order to be able to measure them using the Digital Method. Likewise, CBCTs of those same patients were undertaken using the Dental Picasso Master 3D® and the images obtained were then analysed using the InVivoDental programme. RESULTS: By determining the regression lines for both measurement methods, as well as the difference between both of their values, the two methods are shown to be comparable, despite the fact that the measurements analysed presented statistically significant differences. CONCLUSIONS: The three-dimensional models obtained from the CBCT are as accurate and reproducible as the digital models obtained from the plaster study casts for calculating the Bolton Index. The differences existing between both methods were clinically acceptable.

A study on the reproducibility of cephalometric landmarks when undertaking a three-dimensional (3D) cephalometric analysis.

OBJECTIVES: Cone Beam Computerized Tomography (CBCT) allows the possibility of modifying some of the diagnostic tools used in orthodontics, such as cephalometry. The first step must be to study the characteristics of these devices in terms of accuracy and reliability of the most commonly used landmarks. The aims were 1- To assess intra and inter-observer reliability in the location of anatomical landmarks belonging to hard tissues of the skull in images taken with a CBCT device, 2- To determine which of those landmarks are more vs. less reliable and 3- To introduce planes of reference so as to create cephalometric analyses appropriated to the 3D reality. STUDY DESIGN: Fifteen patients who had a CBCT (i-CAT) as a diagnostic register were selected. To assess the reproducibility on landmark location and the differences in the measurements of two observers at different times, 41 landmarks were defined on the three spatial axes (X,Y,Z) and located. 3.690 measurements were taken and, as each determination has 3 coordinates, 11.070 data were processed with SPSS statistical package. To discover the reproducibility of the method on landmark location, an ANOVA was undertaken using two variation factors: time (t1, t2 and t3) and observer (Ob1 and Ob2) for each axis (X, Y and Z) and landmark. The order of the CBCT scans submitted to the observers (Ob1, Ob2) at t1, t2, and t3, were different and randomly allocated. Multiple comparisons were undertaken using the Bonferroni test. The intra- and inter-examiner ICC's were calculated. RESULTS: Intra- and interexaminer reliability was high, both being ICC ≥ 0.99, with the best frequency on axis Z. CONCLUSIONS: The most reliable landmarks were: Nasion, Sella, Basion, left Porion, point A, anterior nasal spine, Pogonion, Gnathion, Menton, frontozygomatic sutures, first lower molars and upper and lower incisors. Those with less reliability were the supraorbitals, right zygion and posterior nasal spine.

Long-term stability of surgical-orthodontic correction of class III malocclusions with long-face syndrome.

OBJECTIVES: In the first place, to evaluate skeletal changes of the maxilla and mandible induced by surgical-orthodontic correction of malocclusions class III with long-face syndrome and secondly, to analyze the stability of these skeletal changes in the long term (more than 6 years). DESIGN OF STUDY: A retrospective, unicentric and longitudinal study of 19 patients who had undergone surgical and orthodontic therapy for class III skeletal malocclusion with long-face syndrome was undertaken. A cephalometric analysis based on 8 angle measurements, and statistical analyses at three different points in time (before orthodontic treatment, after orthognathic surgery and after a retention period of at least 6 years) were carried out. RESULTS: The changes produced following surgery show that, with the exception of the maxillary plane and the facial axis, all other variables presented changes of great statistical difference. CONCLUSIONS: Skeletal changes after orthodontic-surgical correction present maxillary advance, mandibular regression and mandibular anterorotation. The angles that represent the mandibular vertical position (ramus angle, goniac angle and mandibular plane angle) showed statistically significant relapses and no stability in contrast to the facial axis.

Long-term analysis of upper incisor crowding. A longitudinal study orthodontically treated patients.

INTRODUCTION: Although there are numerous studies in the literature on alignment stability in the lower arch, there are few referring to the upper arch. AIMS: To assess upper arch stability (irregularity index, widths and length of arch, overjet and overbite) in orthodontically treated patients by comparing late incisor stability with the initial malocclusion and type pf treatment undertaken. STUDY DESIGN: The study models of 51 patients, treated with or without extractions, were analysed at three different points in time: pre-treatment (T1), post-treatment (T2) and post-retention (T3) (average 5 years). The following parameters were measured: irregularity index, arch length, inter-canine and inter-molar widths, overjet and overbite. RESULTS: The results showed that upper incisor crowding relapses, although a net improvement is noted in comparison to the initial state both in cases treated with or without extractions. The arch length also relapses in both cases. The inter-canine and inter-molar widths as well as the overjet and overbite are stable in the long term. The long-term response of maxillary incisor alignment is unpredictable. CONCLUSIONS: There is a statistically significant reduction in incisor irregularity, length and width of arch (inter-canine and inter-molar widths), whereas overjet and overbite undergo a reduction of little magnitude. No statistically significant correlation is noted between late incisor stability and the initial malocclusion or type of treatment.

Tooth size changes with age in a Spanish population: percentile tables.

OBJECTIVES: The aims of this work were: firstly, to draw up tables of percentile tooth sizes similar to those of Sanin and Savara for three age groups of a Spanish population; secondly, to describe changes in tooth size between those groups over time, as well as observing any sexual dimorphism and, finally, to compare both the Spanish and Sanin and Savara 's American population samples. MATERIAL AND METHODS: The sample included 359 patients and was divided into three age groups: adolescents, young adults and adults, of both genders. After dental cast digitalization, mesiodistal tooth-size was measured on each dental cast using a digital method. Dental size tables organized by percentiles for each group of age and gender were drawn up. Percentiles under 30 were considered as small, between 30 and 70 as average, and above 70 as large. As symmetry was found between contralateral teeth, the mean between the teeth of the two semi-arches was considered. RESULTS: The mesiodistal tooth sizes of adolescents did not present statistically significant differences between genders, in contrast to the two other age groups. CONCLUSIONS: Mesiodistal tooth diameters tended to diminish with age, especially in women, in the Spanish population. The values obtained for our dental tables, organized by percentiles, were slightly higher than those found by Sanin and Savara in an American population, especially for women.

Dental arch changes from adolescence to adulthood in a Spanish population: a cross-sectional study.

OBJECTIVES: Given the controversy in the literature about the variations in intercanine and intermolar distances and arch perimeter once the eruption of permanent teeth is completed, the aims of this study were to assess the changes of these measures with age, analyzing its sexual dimorphism and variability in a Spanish population. STUDY DESIGN: 188 Spanish individuals distributed in three age groups were selected: 63 adolescents (mean age: 14.15 years), 62 young adults (mean age: 21.9 years) and 63 adults (mean age: 40 years). The intercanine and intermolar distances and arch perimeter were measured in each dental cast from each individual of the sample using a digital method. The results were compared between sex and age groups, the sexual dimorphism percentage (%) of each measure and its variability coefficient (VC%) were calculated. RESULTS: The results depend on sex and age and, therefore, these two factors will be analyzed jointly for each of them with the variation coefficient of the measurement. Intercanine and intermolar distances and arch perimeter were greater in men than in women, especially in the young adult and adult groups. CONCLUSIONS: The intercanine distance and arch perimeter tended to decrease with age particularly in the female sex, whilst the intermolar distance didn 't undergo significant changes. The intercanine distance is the dimension that presented the greatest variability, whereas the intermolar distance presented the least. The changes occur in the transition from adolescence (14 years of age) to adulthood (22 years of age) and the subsequent alterations are not relevant.

Mesiodistal sizes and intermaxillary tooth-size ratios of two populations; Spanish and Peruvian. A comparative study.

INTRODUCTION: Adequate tooth-size ratios are required to ensure the satisfactory outcome of orthodontic treatment. Consequently, various methods of measuring tooth-size ratios have been developed being the Bolton ratio the most commonly accepted, known and used one. This ratio depending directly on mesiodistal tooth size has been associated with different ethnic backgrounds. Some authors suggest the need for specific standards for every population. OBJECTIVES: The objectives of our study were; to measure and to compare mesiodistal tooth sizes and the Anterior and Overall Bolton ratios in two different populations, one Peruvian and the other Spanish with the same digital method. MATERIAL AND METHODS: The sample included 149 individuals composed of two groups; 99 Spanish (mean age 14.19), 65 being females and 34 males and 50 Peruvian (mean age 14.46), 18 being males and 32 females. The mesiodistal sizes of each of the patients were measured using a digital method and the Anterior and Overall Bolton ratios were calculated. RESULTS: Tooth size does indeed involve a strong ethnic component, and the Anterior Bolton ratio is specific for each ethnic group. CONCLUSIONS: The conclusions are; tooth sizes of the Peruvian population were greater than those of the Spanish population. The Anterior Bolton ratio of Peruvian individuals was greater than that of the Spanish, whereas no differences were found for Overall Bolton ratio. These differences suggest the need for specific standards for the Spanish and Peruvian population.

Influence of first and second premolar extraction or non-extraction treatments on mandibular third molar angulation and position. A comparative study.

The mandibular third molar (3M) is the tooth that is most often impacted, with lack of space being one of the reasons. In some orthodontic treatments, premolars are extracted in order to create space. The aims of our study are: firstly, to assess the changes in the angulation and position of the 3M in cases treated either with or without extraction of the first or second premolars; secondly, to analyse the variation in the gonial angle and the degree of inclusion of the 3M; and lastly, to establish a predictive impaction model for 3M. This study included 88 patients: 28 patients treated with extractions of first premolars, 30 with second premolars and 30 without. The initial and final orthopantomography was analysed and the angulation of the 3M was measured, a new variable being created to determine the degree of 3M inclusion in the mandibular ramus. The results show that the angulation of 3M improves with time, regardless of treatment, and presents a greater disinclusion in cases treated with extractions. The gonial angle tends to diminish with age in all cases. The conclusions suggest that other factors may influence the angulation and position of 3M and that it is not possible to establish a predictive impaction model.

Influence of skeletal class in the morphology of cervical vertebrae: A study using cone beam computed tomography.

OBJECTIVES: To quantify the prevalence of cervical vertebrae anomalies and to analyze any association between them and skeletal malocclusions or head posture positions in the same study. MATERIALS AND METHODS: Two hundred forty patients who were attending the Department of Orthodontics of the University of Valencia for orthodontic treatment were selected and divided into three groups: skeletal Class I (control group, 0°

Do Bolton's ratios apply to a Spanish population?

INTRODUCTION: Previous studies have shown that populations differ with respect to interarch tooth-size relationships, and differences in tooth sizes are not systematic. The aims of this study were to determine the Bolton ratios in Spanish subjects. METHODS: We used a digital method and measured the casts to the nearest 0.05 mm. The sample consisted of 100 pairs of dental casts of Spanish subjects. The Kolmogorov-Smirnov test, t test, and 95% confidence intervals were used. RESULTS: Anterior tooth-width ratios were 78.31% +/- 2.59% for women and 78.34% +/- 2.16% for men (P = .955). Total tooth-width ratios were 91.91% +/- 2.04% for women and 92.10% +/- 1.73% for men (P = .668). No significant differences were found in tooth-width ratios according to sex, so the sexes were pooled and new ratios calculated: 78.32% +/- 2.45%, CI 95% (77.83%-78.81%), for the anterior tooth-width ratio and 91.97% +/- 1.95%, CI 95% (91.58%-92.35%), for the total tooth-width ratio. CONCLUSIONS: Twenty-one percent of the subjects had a significant anterior discrepancy (greater than 2 SD from Bolton's), and 5% had a total discrepancy. Differences between Spanish values and Bolton's were significant, and specific standards for Spanish people might be needed.

A new, accurate and fast digital method to predict unerupted tooth size.

The sum of the lower incisor tooth width has been proposed as the best predictor for calculating unerupted canine and premolar mesiodistal tooth sizes. The aims of this study were to develop a new, fast, and accurate computerized method to predict unerupted mesiodistal tooth sizes and to determine which reference tooth or combination of reference teeth was the best predictor for canines and premolars in a Spanish sample. The dental casts of 100 Spanish adolescents with permanent dentition were measured to the nearest 0.05 mm with a two-dimensional computerized system. The goal was to predict unerupted canine and premolar mesiodistal tooth sizes using the sizes of the upper central incisor, upper and lower first molar, or a combination of these as a reference and using a specific mesiodistal tooth-size table. The results showed that the Digital Method proposed was very accurate in predicting unerupted canine and premolar tooth size. The combination of the sums of the permanent upper central incisor and the lower first molar was the best predictor for canines and premolars in this sample. Upper arch teeth were better predicted than lower arch teeth. The upper lateral incisor provided the worst predictions.

Digital diagnosis records in orthodontics. An overview.

Digital technology is becoming day by day a more important procedure in most of the clinic activities and, thus, orthodontists are increasingly adding digital technology to their orthodontics records. In this article we want to outline the advantages and disadvantages of the use of digital photography, digital radiography as well as one of the latest developments: the digital study stone casts. We will also present the state of the art related to dentists that use these digital records routinely in our country.

A comparative study of the pharyngeal airway space, measured with cone beam computed tomography, between patients with different craniofacial morphologies.

PURPOSE: The present study aims to determine any existing association between airway dimensions, measured with cone beam computed tomography (CBCT), and the different patient craniofacial morphologies. MATERIAL AND METHODS: Sixty CBCT (Dental Picasso Master 3D) images, from patients treated at the Orthodontics Master at Valencia University were selected. The program InVivoDental 5.1 was used to visualize sections, analyze three-dimensional images, and perform airway measurements in the three planes of the space. Intra- and interobserver error methods were recorded. After that, measurements at three different levels of the airway (upper, medium, lower) were taken, in both the anteroposterior and transversal directions of the airway space. The area (mm(2)) of the airway space at the three levels was also measured. RESULTS: In the anteroposterior airway measurements, there were differences between the measurements by level. The magnitude of these differences depended on the skeletal pattern of the individual. In the transversal airway measurements and in the area airway measurements, there were no differences according to the skeletal pattern. However, in the transversal direction, measurements in the lower level were significantly higher than in the superior level in all cases. When measuring the area, significantly higher measurements in the upper level were recorded. The homogeneity between medium and lower levels decreased gradually from class I to class III subjects. CONCLUSIONS: No statistically significant results were observed that related the anteroposterior and vertical skeletal craniofacial morphology with airway dimensions, although some specific associations have been detected for certain airway levels or for pattern combinations.

New regression equations for predicting human teeth sizes.

INTRODUCTION: The aims of the study were; to evaluate the applicability of the Moyers and Tanaka-Johnston Methods to individuals with a Spanish ancestry, to propose new regression equations using the lower four permanent incisors as predictors for the sum of the widths of the lower permanent canine and premolars, and to compare the new data to those from other populations. METHODS: A total of 359 Spanish ancestry adolescents were selected. Their dental casts were measured using a 2D computerized system. Real teeth measurements were compared with those predicted using Moyers probability tables and Tanaka and Johnston equations, and standard regression equations were then developed. RESULTS: Results showed that Upper and Lower Canine and Premolar (UCPM, LCPM) predictions are quite different depending on the used method. Moyers tables can only be validly applied to a 75% percentile for the mandible in both, males and females, 85% in males and 90-92% in females. CONCLUSIONS: Moyers predictions tend to underestimate UCPM and LCPM whereas Tanaka-Johnston predictions tend to overestimate them. Equations for estimating the combined width of the unerupted canine and premolars were; Male: UCPM = 12.68 + 0.42 LI and LCPM = 11.71 + 0.44 LI. Female: UCPM = 12.06 + 0.43LI and LCPM = 10.71 + 0.46 LI.

Smile esthetics from odontology students' perspectives.

OBJECTIVES: To analyze the perception of smile esthetics and its alterations in dental degree students; to determine whether there are differences in that perception among students in different study years on those courses and between genders; and to determine if the circumstance of having received prior orthodontic treatment could influence that perception. MATERIAL AND METHODS: Students (n = 192) in different study years of the dental degree course at the University of Valencia, Spain, analyzed two photographs of a patient in which, by means of computer software, midline diastema, upper and lower midlines, crown length of the maxillary right central incisor, occlusal cant, and "gummy" smile were altered. Students assessed the photographs on a scale from 1 to 10. Statistical analyses for assessing each group's level of perception were carried out. RESULTS: After checking the validity of the study, it was observed that the students' ability to detect alterations in smile esthetics did not improve over their degree courses, given that the differences do not present a linear development. There were no differences between genders and between those who had or had not undergone an orthodontic treatment. CONCLUSIONS: There are no statistically significant differences between the results of students in different study years or between genders. The circumstance of having undergone prior orthodontic treatment is not a determining factor in the ability to perceive such anomalies.

Effects of endodontic treatment on apparent Young's modulus of human teeth: in vitro study using speckle interferometry.

The introduction of new techniques for endodontic procedures requires the analysis of the biomechanical behavior of dental structures. Digital speckle shearing pattern interferometry (DSSPI) is a nondestructive optical measuring technique that allows one to directly quantify deformations in teeth that are subjected to stress. DSSPI technique was applied to measure small deformations caused by flexion in different types of teeth. The test was carried out both before and after endodontic treatment with the ProTaper method in order to evaluate the variation of dental elasticity, taking into the account the type of tooth and the endodontic treatment. The results obtained show that dental elasticity, established by means of the apparent Young's modulus, before and after the endodontic treatment, differs between incisors and premolars. The endodontic process does not affect dental elasticity (p>0.7). Specifically, 57.1% of central incisors and 56.3% of second premolars slightly increase their elasticity after the endodontic process. In turn, 42.9% of central incisors and 43.7% of second premolars slightly decrease elasticity. The endodontic treatment especially affects the "neutral fibre"; therefore, there is little influence on elasticity by flexion. However, after finishing the process, the channel was restored with material, which can slightly increase tooth elasticity in some cases.

Cephalometric measurements from 3D reconstructed images compared with conventional 2D images.

OBJECTIVE: To assess whether the values of different measurements taken on three-dimensional (3D) reconstructions from cone-beam computed tomography (CBCT) are comparable with those taken on two-dimensional (2D) images from conventional lateral cephalometric radiographs (LCRs) and to examine if there are differences between the different types of CBCT software when taking those measurements. MATERIAL AND METHODS: Eight patients were selected who had both an LRC and a CBCT. The 3D reconstructions of each patient in the CBCT were evaluated using two different software packages, NemoCeph 3D and InVivo5. An observer took 10 angular and 3 linear measurements on each of the three types of record on two different occasions. RESULTS: Intraobserver reliability was high except for the mandibular plane and facial cone (from the LCR), the Na-Ans distance (using NemoCeph 3D), and facial cone and the Ans-Me distance (using InVivo5). No statistically significant differences were found for the angular and linear measurements between the LCRs and the CBCTs for any measurement, and the correlation levels were high for all measurements. CONCLUSION: No statistically significant differences were found between the angular and linear measurements taken with the LCR and those taken with the CBCT. Neither were there any statistically significant differences between the angular or linear measurements using the two CBCT software packages.

Allergic contact dermatitis associated with the use of facemask on a patient with a history of atopy.

Allergic contact dermatitis (ACD) is a skin inflammation caused by an allergic reaction after contact with small external substances capable of being absorbed by the skin. There are several studies describing allergic reactions to intraoral orthodontic appliances, especially those containing nickel. Allergic reactions due to extraoral appliances are not as frequent, and there are relatively few studies about them. Extraoral eactions are attributed to metallic, elastic, or textile parts of the extraoral appliances. This article's purpose was to report the appearance of an allergic contact dermatitis reaction in a 9-year, 2-month-old female patient, with a history of atopic dermatitis, after an orthodontic facemask was fitted. Rapid maxillary expansion was also performed with a Hyrax appliance while a facemask was used. Early diagnosis of this pathology is essential in order to achieve a total regression of the reaction. Orthodontists should be aware that ACD can be caused by facemasks in predisposed patients.