WALA Ridge Research Articles

Srovnání změn v dolním zubním oblouku u pacientů léčených konvenčními zámky a samoligujícími zámky

Aim: The aim was to assess the changes in the mandible in patients treated with conventional brackets compared to those treated with self-ligating brackets. In particular, we focused on the degree of transversal changes and the length of therapy. Material and method: The sample included 43 patients; 11 men and 32 women. The mean age was 22.2 years. The patients had complete permanent dentition, were treated without extractions, molars in Angle Class I. The subjects were divided into two groups – conventional brackets, self-ligating brackets. Measurements were performed in scans of cast models made prior to therapy (T1), after removal of fixed appliance (T2), the length of treatment was given in months. The changes in intercanine and intermolar distance were compared in teeth and in relevant points on WALA ridge of the mandible. ORTODONCIE | ročník 33 | č. 2/2024 ODBORNÉ PRÁCE / ORGINAL ARTICLES 29 www.ortodonciejournal.cz | e-mail: redakce@ortodonciejournal.cz, office@ortodonciejournal.cz Results: In lower first molars the change in intermolar width was significant in both groups both at T1 and T2. The change was significantly bigger in the group with self-ligating brackets. The change in intercanine width between T2 and T1 was statistically significant only in the group with self-ligating brackets when measured on canine tips. Measurements at FA points (the most prominent point in the middle of longitudinal axis of the clinical crown) did not prove significant change. At WALA the change between T2 and T1 was significant only in the group with self-ligating brackets and only in first lower molars (clinically the change was small). The change in the distance WALA-FA in first lower molars on the left and on the right between T2 and T1 was statistically significant in both groups, however, it was significantly bigger in the group with self-ligating brackets. The difference in the length of therapy was not statistically significant. Conclusion: In patients with self-ligating brackets there is a greater expansion in first molars and canines. We can also observe more prominent vestibular inclination of canines and first molars. In patien

Wilson curve modification in permanent dentition: a retrospective comparison between clear aligners and continuous archwire treatment.

To evaluate leveling of the Curve of Wilson (COW) by two different treatment appliances (clear aligners [CA] and continuous archwire fixed appliances [FA]) in a permanent dentition sample of patients. Digital casts of 40 patients (CA group = 20 patients; FA group = 20 patients) were collected. Angular values for COW, right and left vertical height difference of lower first molars, and linear distance between lower teeth and the WALA ridge were analyzed for pre- (T1), posttreatment (T2) and on final virtual (ClinCheck) models (T2-CC) of the CA group. An unpaired t-test was used to evaluate significant intergroup differences (P < .05), while a paired t-test was used for posttreatment CA intragroup comparison. FA group showed better control of second molar crown positions compared to CA group (47-WALA = -0.2 ± 0.1 mm, 37-WALA = -0.6 ± 0.3 mm). No significant difference was detected for linear distance of lower first molars and the WALA ridge or for vertical height difference. CA group showed a greater reduction of distance between lower premolars and the WALA ridge (mean difference: -0.5 mm for both 45-WALA and 35-WALA; mean difference: -0.5 mm for 44-WALA, -0.6 mm for 34-WALA). Predictability for the CA group was high for every measurement (87% Right COW, 89% Left COW, 88% 46 Vertical Diff, 87% 36 Vertical Diff). Clear aligner and continuous archwire mechanics were effective in leveling COW. FA was more effective in changing crown position of lower second molars with respect to the WALA ridge, while CA provided a greater distance reduction between lower premolars and WALA ridges compared to FA.

Orthodontic treatment and biological limits: a retrospective clinical trial

BackgroundThe fundamental part of every successful orthodontic treatment is the detailed treatment planning including a precise determination of the virtual treatment objective (VTO) while considering the biological and anatomical limits. The aim of this study is to investigate and to compare the feasibility of the established reference values before and after orthodontic treatment and to determine the usefulness of this parameters as guidance for the sagittal anterior, sagittal posterior and transverse biological boundaries.Materials and methodsThirty-two patients aged 9 to 18 years (12 male and 20 female) with all permanent teeth present were randomly selected for orthodontic treatment with fixed multibracket appliance regardless of the potential malocclusion. The parameters 6-PTV, 1-NB [mm] and the WALA ridge were set for the identification of the transverse, sagittal anterior and sagittal posterior tooth position. The measurements were carried out at the beginning (T0) and at the end (T1) of the orthodontic treatment. They were set in relation with their individual threshold values (G). After the results of the measurements were conducted using the software OnyxCeph3TM (version 3.2.185 (505), Image Instruments GmbH, Chemnitz, DE), they were statistically calculated in the software RStudio (2022.12.0 Build 353 © 2009–2022 Posit Software PBC).ResultsAmong the 32 patients, the mean pre- and post-treatment changes measured through the three parameters in relation to the individual reference values were statistically significant (p < 0.01). The mean values for 6-PTV, 1-NB and the WALA ridge amounted 15.37 mm, 2.56 mm and 4.23 mm at the beginning of the treatment, while after the treatment the measured values amounted 20.31 mm, 2.4 mm and 5.55 mm. These measurements combined with the statistical analysis of the changes of WALA ridge (T0, T1) confirmed that the teeth have been successfully uprighted and aligned. Furthermore, the maxillary first molars have been moved slightly mesially, as proven by the changes in 6-PTV, without certainty as to whether bodily movement or mesial tipping took place. Additionally, the lower incisors have been protruded, slightly exceeding the individual threshold values.ConclusionThe parameters investigated provide a suitable assessment tool for recording the limits of the sagittal posterior, the sagittal anterior and the transverse dimension.

Three-dimensional analysis of the relationship between mandibular retromolar space and positional traits of third molars in non-hyperdivergent adults

BackgroundThe anatomical position of the mandibular third molars (M3s) is located in the distal-most portions of the molar area. In some previous literature, researchers evaluated the relationship between retromolar space (RS) and different classifications of M3 in three‑dimensional (3D) cone—beam computed tomography (CBCT).MethodsTwo hundred six M3s from 103 patients were included. M3s were grouped according to four classification criteria: PG-A/B/C, PG-I/II/III, mesiodistal angle and buccolingual angle. 3D hard tissue models were reconstructed by CBCT digital imaging. RS was measured respectively by utilizing the fitting WALA ridge plane (WP) which was fitted by the least square method and the occlusal plane (OP) as reference planes. SPSS (version 26) was used to analyze the data.ResultsIn all criteria evaluated, RS decreased steadily from the crown to the root (P < 0.05), the minimum was at the root tip. From PG-A classification, PG-B classification to PG-C classification and from PG-I classification, PG-II classification to PG-III classification, RS both appeared a diminishing tendency (P < 0.05). As the degree of mesial tilt decreased, RS appeared an increasing trend (P < 0.05). RS in classification criteria of buccolingual angle had no statistical difference (P > 0.05).ConclusionsRS was associated with positional classifications of the M3. In the clinic, RS can be evaluated by watching the Pell&Gregory classification and mesial angle of M3.

Comparison of cross-sectional orthodontic analysis on digital models using Nemocast and CBCT software

Model measurements and analysis are essential for the diagnosis of orthodontic cases and in the last decade orthodontic diagnosis has increased with technological advances, leaving aside traditional diagnostic methods, such as model analysis, especially when it comes to cross-sectional analysis. The present study seeks to propose to the clinician a simple option in the diagnosis of the transversal problem, through analysis with the CBCT. To support this proposal, data was collected from 40 students who were evaluated according to the parameters established in the study, between the ages of 21 and 27. Data were taken from digital study models in STL format, as well as CBCT. The UPenn analysis was used in the CBCT and applying the Korkhaus and Wala Ridge analyzes for the STL digital models, establishing comparisons of the validity of the results by calculating the predictive values of the positive test and the negative test. Model analysis was performed by measuring, using the NemoCast3D software. The comparison of means of both measures was carried out, which showed that there is no significant difference and then the correlation of measures was made, which proved to be significant in 5 of 7 measures. This model analysis proposal (AN-BAR) can be useful for the clinician in making a decision when performing a maxillary expansion.

A New Approach to Diagnosis to Posterior Cross Bite: Intraoral Photography and Wala Ridge.

A posterior crossbite is an occlusion disorder that occurs in the transverse plane. It occurs when the buccal cusps of the upper premolars and molars engage lingually with the buccal cusps of the lower teeth. It can be unilateral or bilateral (involving one or more teeth) in the primary, mixed, or permanent dentition. A crossbite may appear in early dentition stages and it can be dental or functional. It can lead to skeletal crossbite in mixed dentition. Therefore, early diagnosis and treatment are crucial. Material and methods: The selected sample included 204 patients in growing stage divided into two groups: a study group of 102 patients with posterior crossbite and a control group of 102 patients without malocclusion. To analyze the pathology, intraoral frontal photographs and study models were taken, in which the bone component was measured from the Wala Ridge. Results: The use of the photographs to study the Wala Ridge was confirmed. The mean maxillary width was 57.8 mm (SD 1.7) and mandibular width was 56.4 mm (SD 1.7) for the control group, with a maxillomandibular difference of 1.4 mm (SD 0.7); and 52.7 mm (SD 3.7) and 55.5 mm (SD 3.6), respectively, with a maxillomandibular difference of −2.8 mm (SD 1.4) for the study group. A higher maxillomandibular discrepancy was observed in patients with a posterior crossbite that involved more than one tooth in addition to the permanent first molar. It was also higher in patients with bilateral posterior crossbite. Conclusions: Intraoral frontal photography can be used as a diagnostic method to measure the maxillomandibular difference using the Wala Ridge.

Evaluation of WALA ridge in different facial patterns: A cone-beam computed tomography study

This retrospective study evaluated the buccal bone thickness in mandibular canine, premolar, and molar areas, using as a reference the WALA ridge in patients with various facial patterns. The sample comprised 51 cone-beam computerized tomography scans of subjects divided into 3 groups according to the facial pattern, determined by the Ricketts' VERT index, brachyfacial (group 1), mesofacial (group 2), and dolichofacial (group 3). A quantitative analysis of the buccal bone thickness was made in cone-beam computerized tomography scans in the region of the mandibular dental arch corresponding to the WALA ridge. The intergroup comparison of buccal bone thickness was performed with a 1-way analysis of variance and Tukey tests. Buccal bone thickness was similar among the groups, and it increased progressively from the mandibular first to the second molars. In the canine and premolar regions, the thickness was less and often not visible on tomography. There was no difference in the buccal bone thickness in the mandibular dental arch region corresponding to the WALA ridge reference among facial patterns, except for the mesial roots of the second molars, which were thicker in brachyfacial subjects than in dolichofacial subjects. The use of the WALA ridge as a clinical reference for individualized orthodontic arch diagramming should be made with caution and independent of the facial pattern.

Comparison between Digital Casts and Cone Beam Computed Tomography for Measuring Maxillary Transverse Dimensions in Patients with Impacted Canines.

Cone beam computed tomography (CBTCT) scans (n = 45) and digital dental casts (n = 45) were both used to measure the maxillary transverse dimensions in patients with impacted maxillary canines. The objectives were to explore the associations of these dimensions with the impaction and patient characteristics, and to compare the measurements between these techniques. The maxillary width was measured on scans and casts at the Walaridge, and the intermolar width and interpremolar width levels were measured at the first and second premolars (measured from the buccal grooves and the palatal cuspids, and the palatal and lingual amelocemental junctions). Two examiners independently compared the measurements between the control quadrants (without impaction) and the case quadrants (with impaction) in patients with unilateral impactions, and between the unilateral and bilateral impaction groups. The interclass correlation coefficient (ICC) was calculated to assess the interexaminer reliability and paired or independent Student’s t-tests and ANOVAs were used for comparisons. The ICCs were 0.887 and 0.919, globally, for the measurements on the CBCT scans and casts, respectively, which indicates the excellent interexaminer reliability. On the CBCT scans, statistically significant differences were found between the case and control quadrants in the transverse measurements at the lingual level on the upper first molars, and at the WALA ridge level on the upper second premolars (p < 0.05) in the unilateral impaction group. Significant differences were found between the case quadrants in the unilateral versus the bilateral groups at the WALA ridge on the second premolars in casts (p < 0.05), and at the lingual point on the first molars on the CBCT scans (p < 0.05). No statistically significant differences in the transverse measurements were observed between the impacted buccal and palatal canines on either the casts or CBCT scans. To the best of our knowledge, this is the first study to compare the transverse measurements between digital models and CBCT scans.

Evaluation of Horizontal Distance between WALA-FA Point in Angle's Class I, Class II, and Class III Malocclusion.

Introduction:The objective of the study was to measure the horizontal distance between the FA-WALA (Facial Axis Point-William Andrews and Larry Andrews) of posterior teeth in Angle's Class I, Class II, and Class III malocclusions and to assess the depth of the Curve of Spee, to find the correlation between intercanine FA and intercanine WALA and its significance.Material and Methods:Sixty pretreatment mandibular casts of patients with an age range of 18–35 years were included. A sample size of 20 was evaluated in Angle's Class I, Class II, and Class III, respectively. The WALA ridge and FA points were marked in the model and calibrated using the digital Vernier caliper.Results:There was an incremental increase in the horizontal distance from the FA-WALA in the posterior teeth. The mandibular intercanine FA-FA and intercanine WALA-WALA distance were greater in Angle's Class III group when compared to Angle's Class II. The Curve of Spee measurement was increased in Angle's Class II group, while Angle's Class III had a flat curve.Conclusion:The horizontal distance between FA-WALA increased incrementally in the posterior teeth in Angle's Class I, Class II, and Class III malocclusions. In Angle's Class II malocclusion, the Curve of Spee measurement was increased and had a narrower mandibular arch.

Evaluation of symmetry behavior of surgically assisted rapid maxillary expansion with simulation-driven targeted bone weakening

ObjectivesSurgically assisted rapid maxillary expansion (SARME) is a treatment modality to overcome maxillary constrictions. During the procedure of transverse expansion, unwanted asymmetries can occur. This retrospective study investigates the transverse expansion behavior of the maxilla utilizing a simulation-driven SARME with targeted bone weakening.Materials and methodsCone beam computer tomographies of 21 patients before (T1) and 4 months after treatment (T2) with simulation-driven SARME combined with a transpalatal distractor (TPD) and targeted bone weakening were superimposed. The movements of the left, right, and frontal segments were evaluated at the modified WALA ridge, mid root level, and at the root tip of all upper teeth. Linear and angular measurements were performed to detect dentoalveolar changes.ResultsDentoalveolar changes were unavoidable, and buccal tipping of the premolars (6.1° ± 5.0°) was significant (p < 0.05). Transverse expansion in premolar region was higher (6.13 ± 4.63mm) than that in the molar region (4.20 ± 4.64mm). Expansion of left and right segments did not differ significantly (p > 0.05).ConclusionSimulation-driven SARME with targeted bone weakening is effective to achieve symmetrical expansion in the transverse plane.Clinical relevanceSimulation-driven targeted bone weakening is a novel method for SARME to achieve symmetric expansion. Dental side effects cannot be prohibited.

Comparison of dental arch forms created from assessment of teeth, alveolar bone, and the overlying soft tissue.

The objective of this study was to determine whether there are differences among the arch forms created from assessments of tooth surfaces, alveolar bone, and overlying soft tissue. This study included 18individuals who presented with aclassI malocclusion, mild crowding, and acone beam computed tomography (CBCT) image of good diagnostic quality. The facial axis point was chosen to create the arch form from teeth, the Bowman-Kau (BK) point was used to establish the arch form from alveolar bone, and the WALA ridge was used to calculate the soft tissue arch form. Apredetermined algorithm was then used to create five separate arch forms per patient. These arch forms were categorized according to shape and were superimposed. The distances between the tooth-, bone-, and soft tissue-derived arch forms were calculated. The calculated distances between all arch forms were significantly different. The distances between the tooth- and bone-derived arch forms were larger for the mandible compared to the maxilla (mean 3.30 vs. 2.48 mm, respectively). The larger distances seemed to be located more posteriorly in the arch than anteriorly. The distance between tooth- and soft tissue-derived arch forms was largest for the second premolar (2.35 ± 1.59 mm), first molar (2.86 ± 0.63 mm), and second molar (3.25 ± 0.87 mm). There were no significant differences in the distance between the tooth- and either bone- or soft tissue-derived arch forms with regard to sex. The arch form shapes obtained from the teeth, alveolar bone, and soft tissue are correlated and show the same general shape. Although future large-scale studies are needed for confirmation, our results suggest that evaluating the easily visualized external features, including the WALA ridge, can adequately predict the underlying bone shape, and thus the desired arch form. Nevertheless, the shapes vary significantly between patients, so the final treatment plan should be individualized rather than relying on over-simplified general wire shapes.

Selected Orthodontic Principles for Management of Cranio-Maxillofacial Deformities.

An understanding of fundamental orthodontic principles involving diagnosis, treatment planning, and clinical strategies is essential for achieving successful outcomes in the treatment of craniofacial patients, particularly cleft lip/palate. This article focuses on: customizing a mandibular dental arch form using the WALA ridge; accurately diagnosing the maxillary skeletal transverse dimension (cusp to cusp/fossa to fossa); coordinating the upper dental arch with the lower; using a smiling profile and glabella vertical to assess anteroposterior jaw position; and leveling the mandibular curve of Spee while considering the lower one-third of the face. These concepts influence treatment outcomes to the extent they are used.

Use of the WALA ridge to evaluate mandibular molar inclination measured to American Board of Orthodontics standards

ObjectiveEvaluation of mandibular molar inclination provides valuable information to the orthodontist when evaluating posterior functional occlusal relationships, diagnosing and treating transverse skeletal and dental relationships, and assessing the quality of orthodontic treatment finishing. Traditional evaluation methods rely on radiographs or diagnostic dental models. Identification of a clinical anatomic landmark that can be evaluated chairside and reliably produces desired treatment results would prove valuable to the clinician. Materials and MethodsPlaster dental casts of 60 posttreatment patients were evaluated for mandibular molar inclination by American Board of Orthodontics (ABO) Cast-Radiograph evaluation standards and compared with the mandibular anatomic landmark the WALA ridge. ResultsMandibular first molars conforming to ABO standards with a vertical difference in buccal and lingual cusp heights ≤1.0 mm had an average horizontal WALA-facial axis (FA) distance of 2.56 mm, which was significantly smaller than the 3.11 mm found when molars were ABO nonconforming with vertical cusp height differences of >1.0 mm to ≤2.0 mm (P < 0.001). Mandibular first molars with WALA-FA distances of ≤2.5 mm were not significantly more likely to be ABO conforming than those with WALA-FA distances of >2.5 mm. ConclusionsMandibular molars with vertical differences in buccal and lingual cusp heights meeting the ABO standards for inclination have significantly smaller horizontal tooth to mandibular bone distances (WALA-FA).

A CBCT evaluation of root position in bone, long axis inclination and relationship to the WALA Ridge

Correct tooth position in all planes of space while respecting the boundaries of the underlying bone is important for stability of teeth after orthodontic treatment as well as the health of the supporting periodontium.1,2 The aim of this study was to determine: 1) if mandibular posterior teeth are more centered over basal bone when they are more upright or close to WALA Ridge norms proposed by Andrews3; 2) if mandibular posterior teeth are more centered in alveolar bone when they are more upright or close to the WALA Ridge norms; 3) if the estimated center of resistance mandibular posterior teeth is most often centered in alveolar bone; and 4) if the WALA Ridge is located at or near the estimated center of resistance of mandibular posterior teeth. A sample of 34 pre-treatment CBCT scans and mandibular casts of patients ages 12–18 were included in the study. CBCT scans were digitized and analyzed using the Carestream 3D Imaging Software Version 3.5.7. Casts were digitally scanned using the Ortho Insight 3D scanner. The WALA Ridge horizontal measurements were made using the Six Elements™ software (MotionView, Chattanooga, TN). The WALA Ridge vertical measurements were obtained from the casts using a digital caliper. Coronal CBCT images were used to measure tooth positions of pre-treatment mandibular posterior teeth relative to surrounding bone. Centeredness of teeth within the bone was quantified and compared to their inclination and to the WALA Ridge location: D1, D2, D3 and D4. Data were analyzed using the JMP version 10 SAS Software. Descriptive statistics were used to calculate the mean, standard deviation, minimum, and maximum values for the distance between WALA Ridge vertical and CR, D2, D3 and D4 for each of the posterior teeth. Single linear regression analysis was performed to evaluate the relationship between both the long axis inclination and WALA Ridge variables compared to the D1, D2, D3, variables. No statistical significance was found for centeredness of mandibular posterior teeth over basal bone when they were more upright or approached WALA Ridge norms. No statistical significance was found for centeredness of mandibular posterior teeth in alveolar bone when they were more upright or approached the WALA Ridge norms. Significant differences were found for the mandibular posterior teeth center of resistance being centered in the alveolar bone regardless of the long axis inclination or WALA Ridge norms (p-value <0.05). Significant differences were also found for the Wala Ridge being located at or near the center of resistance of mandibular posterior teeth (p-value <0.05). 1) More upright mandibular posterior teeth based on long axis inclination or mandibular posterior teeth more closely related to the WALA Ridge landmark are not more centered over basal bone. 2) More upright mandibular posterior teeth based on long axis inclination or teeth more closely related to the WALA Ridge landmark are not more centered in alveolar bone. 3) The center of resistance of all mandibular posterior teeth can most often be found in the center of the alveolar bone regardless of inclination. 4) The WALA Ridge is located at or near the center of resistance for all mandibular posterior teeth. 5) The WALA Ridge may be a useful landmark for customizing mandibular arch form if teeth are tipped to an upright position.

Comparison of WALA ridge and dental arch dimensions changes after orthodontic treatment using a passive self-ligating system or conventional fixed appliance.

To compare changes in WALA ridge and mandibular dental arch dimensions in orthodontic patients treated with a passive self-ligating system and conventional appliances. Original paper. Orthodontic department at Inga University Center, Maringá, PR, Brazil. Pretreatment (T1) and posttreatment (T2) dental casts of 60 patients with Class I malocclusion treated with slight to moderate crowding that were divided into two groups. Group 1: 30 patients treated with a passive self-ligating system, at a mean initial age of 17.68 years and mean treatment time of 2.31 years. Group 2: 30 patients treated with conventional appliances, at a mean initial age of 19.23 years and mean treatment time of 2.56 years. Measurements were taken using a digital caliper directly on pre and posttreatment dental casts to evaluate the transversal dimension behavior of the mandibular dental arch and the WALA ridge width. Self-ligating group presented an increase in WALA ridge width and mandibular transversal dimensions significantly greater than the conventional group, with the exception of intermolar cusp tip distance and intercanine WALA ridge. There was no statistically significant difference between the groups. There was also observed a significantly greater increase of the transversal buccal axis dimensions in the premolar area when compared to the WALA ridge increase in both groups. Treatment with a passive self-ligating system resulted in a significantly greater increase of the WALA ridge width and mandibular arch dimensions when compared to conventional appliance.

Morphological changes of dental and basal arch forms in skeletal class II malocclusions before and after extraction treatment

Objective To study the variation of the dental and basal arch forms before and after orthodontic treatment of patients with skeletal class Ⅱ malocclusion by tooth extraction. Methods The mandibular dental casts of 25 skeletal class Ⅱ patients were laser scanned before and after treatment. The facial axis (FA) points, which were used to represent the dental arch, and the WALA point, which were used to represent the basal bone, were identified for each tooth from the right first molar to the left first molar. We constructed the curve with points of projection of the FA and WALA point on the reference plane, and compared the curve of dental arch and basal bone before and after treatment. Results The width of anterior middle and posterior of the basal arch increased (0.835±1.259) mm, (1.700±1.280) mm and (2.170±1.227) mm, respectively. While the dental arch had a wider width (1.110±1.566) mm in posterior segment but a narrower one in anterior (3.345±2.907) mm. Conclusions The width of middle and posterior of basal bone represented by WALA ridge becomes wider after orthodontic treatment with tooth extraction in patients with skeletal class Ⅱ malocclusion, while the dental arch turns to a new form, which is more coordinated to the basal bone. Key words: Skeletal class Ⅱ malocclusions; Extraction; Dental and basal bone arch form; WALA ridge; Curve fitting

Evaluation of the Relationship between Curve of Spee, WALA-FA Distance and Curve of Wilson in Normal Occlusion.

To test the hypotheses that (i) there is a significant correlation between the curve of Spee (COS), basal arch (WALA ridge) to dental arch distance (WALA-FA distance) and curve of Wilson (CW) and that (ii) the deepening of the COS is affected by the CW and the WALA-FA distance. Mandibular models of 50 patients aged between 20 and 35 years were scanned with TRIOS. The xyz coordinate system was determined, and a reference occlusal plane was generated. The depth of the COS, the CW, and WALA-FA distance were measured using an engineering software. The greatest difference in the measurement of the depth of the COS between the right and left was found to be 0.41±0.50 mm in the first molar teeth. On the basis of the results of Pearson correlation analysis, there was no strong correlation between the depth of the COS, the CW, and the WALA-FA distance. It was shown that there was no strong correlation between the depth of COS, CW, and WALA-FA distance. The CW and WALA-FA distance could not be effective in the deepening of the COS.

Distances between mandibular posterior teeth and the WALA ridge in Peruvians with normal occlusion.

ABSTRACTObjective: The purposes of this investigation were to determine the horizontal distances between the mandibular posterior teeth and the WALA ridge in a sample of Peruvians with normal occlusion and to compare them by tooth type, sex, arch side, and age groups. Methods: 65 dental casts of subjects with normal occlusion were collected. Posterior teeth, except for third molars, were evaluated. The horizontal distances between the occluso-gingival midpoints of the buccal surfaces (FA points) of each tooth and the WALA ridge were measured using a modified digital caliper. The values between each different tooth type within the sample were compared using the ANOVA and Scheffe tests, while comparisons by sex, arch side and age groups, using the Student’s t-test. Results: The mean distances in the sample was 0.96 mm for first premolars, 1.45 mm for second premolars, 2.12 mm for first molars and 2.55 mm for second molars. Statistically significant differences between each of the four tooth types were found. There were no significant differences found between sex, arch side and age groups. Conclusion:The horizontal distances between the mandibular posterior teeth and the WALA ridge increased progressively from the first premolars to the second molars in Peruvians with normal occlusion. The WALA ridge was a good landmark to evaluate the positions of posterior teeth in Peruvians with normal occlusion.

Dental and alveolar arch forms in a Caucasian population compared with commercially available archwires

The aim of this study was to identify an arch form, comprising dentition and alveolus, representative of the Caucasian population, and to compare it with the shape of the main archwires on the market. The study sample comprised 35 pairs of dental casts, taken from the arches of 35 Southern Europeans with ideal natural occlusion. After the dental casts were scanned, the reference points of the dental arches (FA points) and alveolar bone (WALA ridges) were identified with 3D software. Cartesian coordinates and intercanine and intermolar diameters were calculated for each patient, and curves representing the upper and lower dentition, as well as those showing the shape of the lower supporting bone, were traced and compared with those pertaining to different types of commonly used orthodontic archwires. Ideal shapes of the mandibular alveolus and of the upper and lower archwires were calculated and compared with those actually on the market. Statistical analysis showed significant differences between the two, particularly at the upper and lower molars and canines. Likewise, there were significant differences between the shapes of the available archwires and the WALA ridge, except for the intercanine width. None of the commercial archwires examined faithfully represented the shape of the 'ideal' dentition we calculated, particularly at the molars and canines. The bone structure of the mandibular support cannot be used as a guide to the shape of the arch form during orthodontic treatment.

Changes in dental and basal archforms with preformed and customized archwires during orthodontic treatment

ObjectivesTo evaluate changes to the dental and dentoalveolar (WALA Ridge) arch widths with preformed and customized archwires during orthodontic treatment. Methods20 patients treated with preformed archwires and 20 treated with customized archwires were recruited. Pre-treatment (T1) and post-treatment (T2) mandibular casts were used to determine the changes in dental and dentoalveolar arch width measured at the canine, premolar and molar areas. Ratios of transverse dental to dentoalveolar movements were also calculated. Results were compared to an untreated control group with mandibular casts taken at two comparable time points. Data were analyzed using ANOVA and t-test. ResultsSignificant changes in dental and dentoalveolar arch width were found with the preformed archwire group when compared to the control (p<0.05). However, no significant changes in dental and dentoalveolar arch width were found with the customized archwire group compared to the control. Significant correlations were found between the dental and dentoalveolar arch widths. However, the ratios of dental to dentoalveolar transverse change differed between the groups and indicated that the types of movements were contrasting between the preformed and custom arch forms as each expanded the dental arches. ConclusionsThe WALA Ridge is a stable landmark when archwires are customized or shaped to the WALA Ridge. Changes in the WALA Ridge are expected when preformed archwires are used which do not conform to the patient's dentoalveolar arch width defined by the WALA Ridge. This is probably accounted for by the different types of tipping combined with extrusion that both methods employ.