Mandibular Dental Arch Research Articles

Evaluation of Growth and Development of Adolescents' Dental Arch Asymmetry with Normal Occlusion Using Three-Dimensional Digital Models.

Objective The purpose of this study was to observe the dental arch asymmetry in 12-year-olds with normal occlusion during the early permanent dentition stage. Methods Ninety-two 12-year-old students (46 males and 46 females) who had normal occlusion during early permanent dentition were selected from a junior high school in Tangshan, China. Once per year for three consecutive years, a dental cast was obtained from each subject, and the cast was scanned with a 3D digital scanner (R700 3D). The median palatal plane (MPP) and transverse palatal plane (TPP) were used as the reference plane for the transverse and anteroposterior measurements, respectively. Results Most of the dental arch asymmetry indicators decreased with age, but these differences were not statistically significant. The values of the midincisal edge of the upper central incisors (U1), midincisal edge of the upper lateral incisors (U2), upper canine cusp tip (U3), upper first premolar buccal cusp tip (U4), upper second premolar buccal cusp tip (U5), upper first molar mesiobuccal cusp tip (U6MB), and upper first molar distobuccal cusp tip (U6DB) to the TPP were 0.019 mm, 0.279 mm, 0.017 mm, 0.016 mm, 0.016 mm, 0.027 mm, and 0.200 mm, respectively; these values were larger in males than in females (P < 0.05). The values of 2–5, 6MB, and 6DB-TPP were 0.154 mm, 0.102 mm, 0.119 mm, 0.259 mm, 0.206 mm, and 0.123 mm, respectively, larger in the mandibular than in the maxillary dental arch (P < 0.05). The values of the midincisal edge of the lower central incisors (L1), midincisal edge of the lower lateral incisors (L2), lower canine cusp tip (L3), lower first premolar buccal cusp tip (L4), lower second premolar buccal cusp tip (L5), lower first molar mesiobuccal cusp tip (L6MB), and lower first molar distobuccal cusp tip (L6DB) to the MPP were 0.399 mm, 0.197 mm, 0.258 mm, 0.248 mm, 0.214 mm, 0.575 mm, and 0.531 mm, respectively, larger than L1-5, L6MB, and L6DB-TPP (P < 0.05). Conclusion The asymmetry of the dental arch in 12-to-15-year-olds with normal occlusion did not change significantly with age. The anteroposterior asymmetry of the maxillary dental arch is larger in males than in females. With the exception of the central incisor, the anteroposterior asymmetry of the mandibular dental arch is larger than that of the maxillary dental arch. The transverse asymmetry of the mandibular dental arch is larger than the anteroposterior asymmetry.

Determination of Mandibular Arch Form During Mixed Dentition Using Custom Made Template in Sulaimani Governorate

Objectives: The dental arch form and dimensions change continuously and systematically during human growth and development, but this decreases adulthood. During mixed dentition, changes in dental arch forms and the occlusion occur due to teeth movements and growth of the alveolar bone. Usually, changes in the mandibular arch are followed by changes in the maxillary arch. The research aimed to determine the most frequent mandibular dental arch form and its relationship with gender. &#x0D; Methods: The mandibular arch forms of 115 schoolchildren with mixed dentition were examined using their dental casts. Adobe Photoshop© (21.0.0, 2019) program was used to construct a template from photographs of the casts and printed on transparent paper to overlay the casts. The data were collected and calculated using statistical software to determine the frequencies of different arch forms among the studied sample. &#x0D; Results: The sample was composed of 61 males (53%) and 54 females (47%). The oval arch form was the most frequent type with 70 cases (60.9%), followed by the square arch form with 38 cases (33%), and finally the tapered arch form with 7 cases (6.1%). No significant relationship was found between the arch form and the gender of the participants. &#x0D; Conclusions: Oval arch form was the most predominant type of arch form of the mandible in the mixed dentition, and there was no relationship with gender.

Finite element analysis of the stress released by buccinator muscle in the mandibular dental arch during sucking habits

ObjectivesThe effect of buccinator muscle on the mandible need to be more clarified. Finite element method used to estimate the effect of the buccinator during abnormal function on the size and shape of the mandible. MethodsThree-dimensional model of human mandible using Finite element analysis referring to dry normal mandible with teeth as a template, The mechanical characteristic of the materials were supposed to be homogenous, isotropic, and linear elastic. Auto mesh order used to discredit the model under analysis to numerous elements; every element includes numbers of apexes called nodes; the association of elements and nodes called the finite element mesh. The force of (2 ​gm/cm2) had been applied perpendicular to buccal surface of posterior teeth within the mandible representing normal buccinators muscle function on the mandible. While for simulation of abnormal suckling, buccinators muscle force (21 ​gm∖cm2) applied to the same area. Resultsabnormal size and shape of the mandible with malocclusion especially at the posterior teeth area in transverse direction in addition to backward pressure on the chin and anterior teeth result from abnormal suckling force. ConclusionIt could be concluded that abnormal function of buccinators during growth and development could result in size and shape variation of the mandible with concomitant malocclusion.

Association between Intercanine Width and Mandibular Dental Arch Forms.

A descriptive cross-sectional study was conducted to investigate the association between intercanine width and the mandibular arch form in 109 dentate subjects, who visited Orthodontics Department from October 2018 to December 2019. Using Vernier caliper, the intercanine width was measured as the distance between the left and right canines on each cast with the arch form, also categorized as tapered, square or ovoid, using predefined criteria. Spearman's rank correlation demonstrated highly significant association between intercanine width and mandibular dental arch forms, with p value of 0.005. Key Words: Dentate subjects, Mandibular arch forms, Inter-canine width, Sexual dimorphism, Mandibular dental cast.

QUALITY OF LIFE ASSESSMENT IN PATIENTS AFTER PROSTHETIC TREATMENT USING THE DENTAL PROFILE QUESTIONNAIRE

Introduction. Quality of life, objective assessment criterion of which is level of human’s needs and interests satisfaction, is primarily connected with health status. This is why so called “health-related quality of life” is closely associated with patient’s well-being and satisfaction of those aspects of life, that are impacted by disease or treatment process. During the study of oral health related quality of life (OHRQoL, 1996), most authors take the OHIP (Oral Health Impact Profile, G.D. Slade, A.J. Spencer, 1994) approach as a basis, such as OHIP-EDENT (Short Version). Due to the fact, other methods of quality of life assessment are not widely used in dental practice, and it is important to develop new approaches in quality of life study, combined with prosthetic treatment results, considering the appropriate indicators of oral health.&#x0D; The aim of this study is to conduct a personalized dental health indicators assessment reflecting patients’ quality of life after restoration of mandibular dental arch with overdentures.&#x0D; Materials and methods. Main group (MG) comprised 23(54,8%) female patients and 19 (45,2%) males ones (n=42) aged 56-89, whom mandibular overdentures with ball attachments were constructed. Comparison group (CG) consisted of 17(47,2%) women and 19(52.8 %) men (n=36) aged 57-76, who have been using first-timely constructed complete removable mandibular dentures for three years. After use of the Dental Profile Questionnaire, and after detailed anamnestic study, the number of patients’ of both groups responses about possible unfavourable symptoms in use of dental prostheses and the mean value of frequency of those symptoms (1- sometimes, 2- often, 3- mainly) were estimated. Statistical processing of data obtained was performed by standard methods of variation statistics using Statistica 6.0 Program.&#x0D; Results and discussion. The subjective component of our treatment results evaluation of in-depth analysis, after all reflected in extended description of the clinical cases in MG patients development of the current disease — significant loss of teeth with mandibular single remaining teeth / roots (K08.9 according to ICD-10) indicated that quality of life level of these individuals has a close connection with their oral health. According to the overall subjective evaluation of prosthetic treatment results after answering 14 patient’s oral health- related questions, the number of reports of adverse events was markedly different -22.7% in MG patients after 12 months of observation vs. 77.3% of CG patients, and statistically significant (p &lt;0.05) - the decrease in the average score of their frequency.&#x0D; Thus, it can be argued, that in the MG patients satisfaction with the treatment results, that reflected the quality of life level, associated with oral health, was notably higher, than in the CG patiens. So, the dentures were identified applicable (pp.1-6) by 90.9% of MG patients vs. 54.6% of CG patients, accompanying signs (pp.7-12) were positively evaluated by 90.1% vs. 69.0%, and subjective well-being (pp.13-14) was acheived in 90.5% vs. 63.9% of patients in these groups.&#x0D; Conclusions. Results of the research have defined the improvement of all the 14 studied oral health indicators in patients of the main group after 1 year of the examination compared with the previous data after 1 and 6 months of mandibular overdentures use. Patients’ satisfaction with treatment results, reflecting the quality of life level, associated with oral health, confirms the higher efficiency of overdentures use compared to complete removable dentures in mandibular dental arch restoration.

Craniofacial Growth in Adolescence and its Influence on the Mandibular Incisor Crowding.

BackgroundTo analyze craniofacial growth during adolescence from the ages of 12 to 21 years and its relation to late mandibular incisor crowding.Material and MethodsThe study included 61 orthodontically untreated subjects (49% males). Lateral cephalograms were used to assess the jaw growth and inclination of the incisors. Little’s Irregularity Index and the anterior mandibular dental arch depth of mandibular dentition were measured.ResultsA reduction of the skeletal class angle (ANB) was observed in both genders, although it was significant only in males (η2=0.188; p=0.015). The growth of the mandible was more prominent compared to that of the maxilla, and it was more prominent in males than in females. The skeletal vertical dimension, however, demonstrated a significant reduction in both genders (η2=0.527-0.593, p<0.001). The mandibular incisors tended to retrocline in both genders, while the maxillary ones tended to procline in males, and slightly retrocline in females. A decrease in the mandibular dental arch depth occurred in both genders (η2=0.259; p<0.05). An increase in the irregularity of incisors for 1.8±1.7 mm on average (95% CI 1.3-2.2; η2=0.520; p<0.001) was observed in both genders. A logistic regression revealed that less sagittal growth of maxilla (increase of SNA angle ≤2°) and reduction of convexity in skeletal sagittal interjaw relationship (reduction of ANB ≥1°) were significant predictors of the occurrence of crowding (Δ Little Irregularity Index ≥1mm) yielding odds ratios of 4.9 and 4.8.ConclusionsThe differential growth of the maxilla and mandible is related to the occurrence of late crowding, mostly in smaller amounts in maxillary sagittal growth compared to the mandible.

Maxillary and mandibular dental arch forms in a Jordanian population with normal occlusion

BackgroundEthnic background has been claimed to affect arch form. The purpose of this study was to describe and elucidate the maxillary and mandibular arch forms in Jordanian population and to develop a classification method for these forms which could be employed to construct orthodontic archwires accordingly.MethodsThe sample was comprised of study casts of five hundred and twenty subjects (231 males and 289 females with a mean age of 15.4 ± 1.02 years). All subjects had permanent dentition with normal occlusion. A mathematical method associated with a polynomial function of 6th degree was employed to assess the dental arch forms. The resultant arch forms were classified into 5 groups for both the maxilla and mandible utilizing a computer software with special code designed for this study. Each group was subdivided into 3 subgroup sizes namely: small, medium, and large.ResultsCatenary arch form was found in 47% and 41.2% (p ˂ 0.01) of maxilla and mandible arch forms, respectively. Form 2 (which is halfway between ellipse and U-shaped arch form) was found in 27.7% and 26.7%. Medium size arch form was found in 55.4% of the maxillary and 65.6% of the mandibular arch forms.ConclusionCatenary arch form was the most prevalent arch form, followed by wide elliptical form. The other forms, which included tudor arch, tapered equilateral and quadrangular forms were less frequent. Regarding size, the medium size was the most prevalent among the studied samples.

Anatomical features of the human fetus mandible

Aim to obtain new data on the anatomy of the mandible of a human fetus aged 1923 weeks.&#x0D; Material and methods. The object of the study was 40 mandibles of human fetuses of both sexes aged from 19 to 23 weeks. The morphological method (macromicroscopic preparation; the method of saw cuts according to N.I. Pirogov; production of serial histotopograms) and the method of ultrasound scanning by the device VOLUSONS 10, RAB 6 RS sensor in 2D mode and in the "Skeleton" program (3D mode) were used.&#x0D; Results. In fetuses aged 1923 weeks the mandible represents a paired bone connected in the center by a symphysis. According to the shape of the body, it is possible to select wide and short, long and narrow mandibles in a ratio of 2 to 1, respectively 67% and 33%. The length of the alveolar arch is 52.4 5.6 mm (with a range of 45.360.2 mm), the angular width is 23.4 1.7 mm (with a range of 19.027.8 mm). The height of the branch at the cutting level was equal to 6.2 1.4 mm (with a range of 3.69.0 mm). On the anterior surface of the body, one chin opening is determined on both sides, at an average distance of 16.4 mm from the angle of the mandible and at a height of 2.2 mm. On the inner surface of the branch, the opening of the mandible is determined, located at a distance of 3.6 1.1 mm from the angle, 3.2 0.9 mm from the anterior edge of the branch, 4.1 1.2 mm from the posterior edge of the branch. In the second trimester of pregnancy, dental alveoli are determined in the mandibular dental arch of the fetus. Significant sex differences were found for the angle of the mandible (p 0.05). In girls, the angle was 141.1 10.1, in boys 129.5 9.4.&#x0D; Conclusion. The mandible of the fetus at the age of 1923 weeks is formed and has fetal characteristics. During this period, no significant bilateral differences were revealed, sexual differences start to form.

The comparison of maxillary and mandibular dental arch size in male and female Papuan in Surabaya: A cross-sectional study

Aim: The aim of this study was to analyze the differences in the size of maxillary and mandibular dental arch between Papuan males and females. Materials and Methods: An analytical cross-sectional study design was carried out in 12 Papuan males and 12 Papuan females aged above 18–25 years in the Surabaya. Raberin method was used to measure the maxillary and mandibular dental arches width in the dental cast in transversal (L33, L66, L77) and sagittal direction (L31, L61, L71). The statistical analysis was used to analyze the data normality by Kolmogorov–Smirnov test (P > 0.05). In addition, the independent t test was done to determine the differences between groups (P < 0.01). Results: The average sizes of the maxillary dental arch width in the transversal direction in Papuan males, respectively, L33, L66, and L77 were 35.86, 56.58, and 65.61 mm. The average sizes of the maxillary dental arch in the sagittal direction in men L31, L61, and L71 were 4.04, 35.60, and 46.41 mm. The average widths of the maxillary dental arch in a transversal direction in Papuan female L33, L66, and L77 were 32.45, 53.54, and 63 mm. The average sizes of the maxillary dental arch in the sagittal direction in female L31, L61, and L71 were 3.55, 31.94, and 42.42 mm. There was a significant difference between men and female maxillary dental arch in sagittal and transversal measurement (P < 0.01). Conclusion: Male Papuan has a bigger maxillary and mandibular dental arch width as compared to female Papuan. Evaluation of Papuan dental arches may help the orthodontist to determine the diagnosis and treatment plan in this population.

Modified Arnold expander: an alternative for mandibular arch expansion.

ABSTRACTIntroduction: Due to the anatomical constraints of the mandible, mandibular dental arch usually serves as a guideline to determine the required changes in the maxillary transverse dimension. The Schwarz appliance and the Lip Bumper are the traditional orthodontic appliances for mandibular arch expansion in patients with borderline amounts of crowding, and/or transverse discrepancy. However, they often require patient cooperation, which may be a concern for orthodontists in daily practice. Objectives: This article illustrates a simple fixed orthodontic device as an alternative to achieve mandibular arch expansion in patients with moderate tooth-size/arch-length discrepancy. The four reported cases refer to 8 to 10-year-old patients in the mixed dentition, with an Angle Class I or Class II malocclusion, transverse deficiency in both arches, moderate crowding and/or posterior crossbite, combined with compromised smile aesthetics. The patients were treated with rapid maxillary expansion (RME) using Hass expander appliance and the modified Arnold expander (MAE). Conclusion: This low-cost compliance-free orthodontic appliance provided dentoalveolar decompensation by means of uprighting the posterior teeth, with minimal or no adjustments during treatment. The final results were achieved in only three to four months, and fulfilled all treatment objectives, such as an increase in the arch perimeter and width, and a better teeth alignment.

Retreatment of an orthognathic camouflaged case by total lower arch mesialization using temporary anchorage device

Mandibular tooth extractions for camouflage treatments in borderline Class III patients may end up with unpleasing esthetic results which may lead the patient seeking further complicated retreatments. In this case report, we presented a patient's retreatment with a combined orthodontic and orthognathic surgery treatment plan. The treatment strategy involved an innovative temporary anchorage device (TAD)-based method for total mandibular arch mesialization instead of space reopening for first lower premolar replacement with implants. In the current case report, orthognathic management of a Class III adult female is discussed. The patient had a history of an esthetically unsuccessful previous camouflaged orthodontic treatment with two lower premolar extractions. She was prepared for orthognathic surgery using an innovative custom-made sliding jig based on miniscrews for total mandibular arch mesialization with the aim of dental arch decompensation. After gaining the optimal dental arch discrepancy, the patient had orthognathic surgery (maxillary advancement and mandibular setback and advancement genioplasty). Total mandibular dental arch mesialization with the aim of dental arch discrepancy preparation was successfully conducted using TADs. By means of the innovative miniscrew-anchored sliding jig, the patient's satisfactory esthetic and occlusal results were obtained in 22 months. With innovative application of the miniscrews, more practical and reasonable alternatives are available to replace conventional and complicated treatment plans such as space reopening for implants in patients with unsuccessful previous orthodontic therapies.

Analysis of dental and basal bone arch form correlations in skeletal Class Ⅱ malocclusion

This study aimed to establish mathematical equations to describe the dental and basal arch forms in skeletal Class II malocclusion and to investigate correlations between these forms to facilitate clinical diagnosis and treatment design. Cone-beam computed tomography images of 60 patients (30 each with skeletal Class II malocclusion and normal occlusion) were subjected to 3-dimensional volume rendering, image reconstruction, and measurement. Using a computer program written in Java on the Eclipse platform (EclipseFoundation, Ottawa, Canada), a beta function was used to establish mathematical models of dental and basal bone arch forms, and model-fitting was performed. A mathematical model was developed to describe the dental and basal arch forms in skeletal Class II malocclusion. The maxillary and mandibular dental arch lengths were significantly longer in skeletal Class II malocclusion than in normal occlusion, whereas the width of the maxillary molar segment was smaller. The maxillary molar and mandibular intercranial segments in the basal arch were significantly longer in skeletal Class II malocclusion than in normal occlusion, whereas the mandibular intercranial segment width was smaller. The dental arch and basal bone arch forms in the maxilla and mandible follow individual curves, described by a beta function. In skeletal Class II malocclusion, the dental and basal arches are discrepant in horizontal and anteroposterior dimensions, which should be considered during orthodontic treatment planning to improve arch matching.

Various application’s of cone beam computed tomography in dentistry: A review

To get the volumetric data of the maxillary and the mandibular dental arches, the teeth itself, the morphology of the bone, to get the imaging and extent of the bony defects that too with low radiation, cone beam computed tomography plays a major role. CBCT is very much helpful in detecting the three dimensional view of the alveolar bone, helpful in getting the quite accurate extent of the bony defects, helpful in some of the difficult cases of root canal treatment where the dentist is not been able to find the actual curvature of the canal or where the accessory canal has been missed from the primary canal. This technique cone beam computed tomography provides the image to the dentist with minimal of distortion. Keywords: CBCT, Three dimensional imaging, Minimal distortion.

Effect of cervical headgear on dental arch area, shape and interarch dimensions : Arandomized study.

PurposeThe goal was to study the effects of early cervical headgear treatment on maxillary and mandibular dental arch area, shape and interarch dimensions.MethodsThe total study group comprised 67 children aged 7.6 years (standard deviation 0.3) with Angle class II malocclusion collected between 1992 and 1996. The children were randomly divided into two groups of equal size. In the first group, cervical headgear treatment was started immediately and undertaken for 2 years. The remaining patients served as untreated controls. Dental casts were taken and scanned at the beginning of treatment (T0) and at the 2‑year (T1) and 4‑year follow-up (T2). Three-dimensional landmarks describing the positions of maxillary and mandibular incisors, canines, first and second premolars and first molars were used to calculate and visualize the maxillary and mandibular dental arch area and shape using the polynomial equation y = Ax6 + Bx2.ResultsSignificant changes in the shape and area of both maxillary and mandibular dental arches were induced with cervical headgear. The headgear increased dental arch area, sagittal dimensions at the mid-sagittal line and transversal dimensions at all of the measured levels in both dental arches compared to the control group.ConclusionsCervical headgear is an effective treatment device to gain space in both dental arches. Furthermore, when used as an early phase treatment, relapse is relatively small compared to the gained space.

Effects of Combined Rapid Maxillary Expansion and Facemask Therapy on the Mandibular Dental Arch in Mixed Dentition.

The aim of this study was to evaluate changes in the mandibular dental arch and incisor alignment induced by combined bonded Rapid Maxillary Expansion (RME) and Face Mask (FM) therapy in the mixed dentition stage in which leeway space was used throughout the treatment. This retrospective study evaluates pretreatment (T0) and posttreatment (T1) cephalometric radiographs and orthodontic models of 25 patients (mean age: 10.75±2.64), in mixed dentition, having skeletal Class 3 anomaly (ANB<0) with maxillary retrognatism (SNA=77.2±0.68) and bilateral posterior crossbite treated with bonded Hyrax RME-FM. Mean treatment duration was 10.4 months. Dental model measurements were performed using the 3Shape OrthoAnalyzerTM 2013-1 program. Changes in the mandibular incisor and first molar positions were determined on cephalometric radiographs. Statistical evaluation was done with a paired t-test. A significant increase of 1.2 mm was found in intermolar width (p<0.001) in the mandibular dental arch. There was a significant decrease (1.4 mm) (p<0.001) in arch depth and an increase in arch length discrepancy (1.7mm)(p<0.01). There was a significant increase (0.8mm) (p<0.05) in the incisors' irregularity score (LII). IMPA showed a significant decrease (p<0.05). Clinicians should be aware that mandibular crowding tends to increase during this type of combined therapy.

Influence of the Palatine Tonsil Grade on the Morphology of the Maxillary and Mandibular Dental Arches

Influence of the Palatine Tonsil Grade on the Morphology of the Maxillary and Mandibular Dental Arches

Three-Dimensional Evaluation of condylar volume and mandibular length Following Treatment with Skeletally Versus Dentally Anchored Herbst Appliance

Objective: to compare the condylar volume and mandibular length changes of skeletally versus dentally anchored Herbst appliance in the treatment of Class II division 1 patients due to mandibular deficiency. Materials and Methods: The current study was conducted on 17 female patients with their age ranged between 14 and 20 years. All patients were treated by Type IV Herbst appliance. The active group (Group A) comprising 10 patients at whose the Herbst was anchored to the mandible directly by two reconstruction plates located bilaterally in the mandible between the canine and first premolar, while attached to the maxilla through dental splints utilizing orthodontic bands, while the control group (Group B) comprising 7 patients, their CBCT data were taken from a previous study at which the Herbst appliance was anchored with custom made vitalium splints for both the maxillary and mandibular dental arches. The condylar volume and the 3D effective mandibular length was measured using Dolphin software (Dolphin imaging software ver.11.95, Patterson Dental, USA). Statistical analysis was performed with Assistant 7.6 statistics software for Windows (Campina Grande, Paraiba state, Brazil) Results: Condylar volume showed no statically significant change with treatment in both groups, while the 3D effective mandibular length showed statistically significant increase with treatment in both groups. Conclusions: Skeletally anchored Herbst has same mandibular skeletal effect when compared with dentally anchored Herbst.

APPLICATION OF OBJECTIVE AND SUBJECTIVE EVALUATION METHODS FOR MASTICATORY FUNCTION IN PATIENTS WITH MANDIBULAR OVERDENTURES

Appropriate chewing function is an important indicator of oral health, and masticatory efficiency assessment is one of the most objective methods of prosthetic treatment quality control.&#x0D; In the globe dental practice, static and dynamic chewing tests are still considered to be the main methods of masticatory function assessment. Thus, there is an extension of functionally-oriented clinical investigations base, which actualizes the importance of this work.&#x0D; The aim of the work was to evaluate the masticatory function of patients that use mandibular overdentures by studying the results of physiological masticatory test and self-assessment indicators of dental health associated with the use of dentures.&#x0D; Materials and methods. The clinical trials were carried out in two stages. At the first stage upon informed consent an examination of 20 student volunteers aged 18-22 years (control group -I) and 36 patients -17 women, 19 men (aged 57-76 years) with complete mandibular removable dentures (comparison group -II) was proceeded. Patients of the group I underwent physiological masticatory test with agar-agar samples formed according to UMSA method, patients of group II- masticatory test procedure and interview survey. The second stage was performed by the group III–42 persons –23 women, 19 men (aged 56-89 years) at 1, 6 and 12 months after mandibular dental arch restoration with complete removable overdentures, fixed by spherical attachments. Chewing efficiency was determined using masticatory physiological test and problem-oriented questionnaires. Video registration by Nikon Digital Camera D3200 was used to determine chewing time, number of movements and peculiarities of the mastication process.&#x0D; All patients of groups II and III in personal interview survey answered 6 questions about indicators of oral health connected with the use of dentures. Questions were formed according to European Oral Health Indicators (2005). Statistical data analysis was performed by standard statistics variation methods with Statistica 6.0 Program use.&#x0D; Results and discussion. All the parameters of physiological masticatory test: duration of chewing, group I 25,3±2,8 sec. group II 67,3±3,7 sec., group III 60.5±3.5 sec, number of chewing movements in group I was 58.3±4,8, in group II − 82.3±6.3, in group III − 68.8±3,4, samples mass loss: group I − ≤0,13(4,3%), group II − ≤0,21(7,0%), group III − ≤0,18(5,9%). Diminution Index obtained: group I − 1.85±0.5, group II – 3.33±0.7, group III – 2.48±0.5). Masticatory efficiency level in patients of the group III prevailed over group II by the respective parameters. Masticatory test video registration data analysis showed that the patients of group I diminished test samples with bilateral chewing pattern, as the majority of group II patients, while patients in group II employed combined— uni- and bilateral chewing pattern.&#x0D; According to the average values of the expression of all oral health-related questionnaire indicators: chewing difficulties - 2.67 ± 1.35 vs 0.50 ± 0.20*; excessive bite closure efforts - 1.19 ± 0.65 vs 0.57 ± 0.30*; limited food consumption 2.83 ± 1.35 vs 0.59 ± 0.30*; oral lesions 2.39 ± 1.20 vs 0.56 ± 0.30*; difficulty non-chewing movements 2.14 ± 1.05 vs 0.51 ± 0.30*; uncertainty about reaching treatment goals 2.06 ± 1.10 vs 0.66 ± 0.30*. A statistically significant (p &lt;0.05) difference in favor of group III was clearly demonstrated.&#x0D; Conclusions&#x0D; &#x0D; The results of physiological masticatory test and patients interview survey indicated favorable adaptation process to mandibular overdentures with reestablished masticatory function restoration during 12 months of use.&#x0D; Masticatory efficiency and oral health indicators, connected with dental prostheses usage proved the appropriate quality level of prosthetic treatment in mandibular single remaining teeth-attended patients, using dentures fixed by spherical attachments.&#x0D;

Dental arch changes comparison between expander with differential opening and fan-type expander: a randomized controlled trial.

To compare posterior crossbite correction frequency and dentoalveolar changes of the expander with differential opening (EDO) and the fan-type expander (FE). Two-arm parallel randomized controlled trial. Forty-eight patients from 7 to 11 years of age were allocated into two groups. Twenty-four patients were treated with the EDO and 24 patients were treated with the FE. Block randomization was performed. The study was single blind. Digital dental models were acquired before treatment and 6 months after rapid maxillary expansion. The primary outcomes were crossbite correction rate and maxillary arch width changes. Secondary outcomes were interincisal diastema, arch perimeter, length, size and shape, and mandibular dental arch changes. The final sample comprised 24 patients (13 female and 11 male; mean initial age of 7.62 years) in the EDO group and 24 patients (14 female and 10 male; mean initial age of 7.83 years) in the FE group. The crossbites were corrected in 100 per cent of subjects from EDO group and in 75 per cent of patients in FE group. EDO showed greater increases in maxillary intermolar region (P < 0.001), while the FE demonstrated greater increases in the intercanine distance (P = 0.008). Increase in mandibular inter-first permanent molar distance was slightly greater in the EDO group (mean difference of 0.8 mm). Changes in arch length and perimeter were similar in both groups. Both expanders changed the maxillary arch shape. The post-treatment arch shape was larger in the anterior region for FE and in the posterior region in the EDO group. Discomfort during activation was reported by 54 per cent of the participants. A temporary change in the nasal bridge was reported by one patient from FE group. Maxillary arch width and shape changes were distinct between the EDO and the FE. Greater transversal increases of the anterior and posterior regions were observed for the FE and the EDO, respectively. A slightly greater mandibular spontaneous expansion was observed for the EDO only at the molar region. NCT03705871.

Efficacy of different designs of mandibular expanders: A 3-dimensional finite element study

Nonsurgical mandibular expansion has been increasingly performed in recent years because it can effectively expand the mandibular dental arch. However, many types of mandibular expanders have been used in previous studies. No relevant studies have compared the biomechanical responses of different designs of mandibular expansion appliances with screws. Therefore, the purpose of this study was to analyze the stress distribution and displacement of the dentoalveolar structures according to different designs of mandibular screw expanders. Cone-beam computed tomography scans were used for 3-dimensional reconstruction of the mandibular finite element model. Four different designs of mandibular expanders, 1 removable expander (type A) and 3 fixed expanders (types B, C, and D), were added to the finite element models. Expanders were activated transversely for 0.2mm. The initial tooth displacement and von Mises stress distribution were evaluated. All the expanders enlarged the arch dimensions. In types A and B, the stress was mainly concentrated in the region of the anterior teeth, along with greater tooth displacement, whereas in types C and D, greater stress and displacement occurred in the region of the posterior teeth. Type A showed the greatest amount of transverse displacement. Type D was more efficient in the region of the posterior teeth. Types A and B should be used with great caution in the clinic because of their incompatible expansion pattern. Type D is the recommended mandibular expansion appliance because of its appropriate expansion pattern.