Molar Class Research Articles

A Case Report of Kissing Molars Class III

Kissing molars (KMs), first reported by Van Hoof in 1973, refer to molars with occlusal surfaces that contact each other in a single follicular space while their roots extend in opposite directions. This is a case of a 20-year-old male who presented with complaints of right mandibular molar pain with cold water contact and occlusion. Panoramic and cone-beam computed tomography (CBCT) images revealed impaction of the right mandibular third and fourth molars, with the occlusal surfaces contacting each other while the roots extended in opposite directions. KMs are classified according to the impaction of the mandibular first and second molars (Class I), second and third molars (Class II), and third and fourth molars (Class III). Our patient was considered Class III. Given the patient’s preference for surgical treatment, successful teeth extraction and extirpation were performed under intravenous sedation. The patient’s postoperative course was unremarkable. We describe a case of KMs Class III with a cystic variant assessed by panoramic and CBCT images. We additionally review all KMs Class III reported in the literature.

The influence of orofacial functions on sagittal growth and development of occlusion

Introduction. Orthodontics experience has shown that dental compensation of some skeletal irregularities is under the positive influence of external factors. During sagittal development of cranial base and dental arches, they can be placed in relationship of I, II or III skeletal and dentoalveolar class. Malocclusion may be caused by a skeletal irregularity. Despite that, normal occlusion can be achieved by dentoalveolar compensation. The aim of this study was to investigate the influence of orofacial functions on maxillary and mandibular growth, as well as occlusion development in sagittal plane. Material and method. This study consisted of 60 male and female adolescents (average age 15.9). Types of respiration and deglutition were clinically determined. Molar relation and length of dental arch were evaluated from study models. On the lateral cephalograms the following parameters were measured: angles SNA, SNB, ANB, I/SpP and i/MP. Results showed that 78.8% of patients with regular orofacial functions and 11.1% of patients with irregular functions had developed molar class I. Patients with skeletal Class I and Class III and irregular orofacial functions, had protrusion of upper incisors in 88.9% (I) and 80% (III) and high length of maxillary dental arches in 58.8% (I) and 70%(III). Conclusion. There is relationship between orofacial functions and dental compensation of sagittal skeletal irregularities.

Anterior crossbite treatment in the transitional period of mixed dentition: a case report

Anterior crossbite refers to the abnormal vestibulolingual relationship in the sagittal dimension between one or more anterior superior and inferior anterior teeth. It can be classified as dental, functional or skeletal. Each has its own diagnostic criteria and specific treatment, and it is up to the dentist to know how to distinguish between these different natures of malocclusion. In this sense, the aim of this study is to show a case report about an ACM. Patient HCA, female, 7 years old, attending the Preventive Orthodontics Clinic of the Faculty of Dentistry of Araçatuba - UNESP, having as main complaint “untidy front tooth”. The patient has no history of systemic diseases or medication use. The patient was in the first transitional period of mixed dentition with her right maxillary central incisor in crossbite relationship with its antagonists mandibular central incisor. On both sides, the patient had the first permanent molars in Class I relationship, the deciduous second molars with mesial step and the deciduous canines in a Class I. Initially, an acrylic appliance with an expander was installed. Due to lack of cooperation, the treatment plan was changed and the patient received a fixed appliance with a 2x2 configuration, with brackets on maxillary central incisors and edgewise tubes on maxillary deciduous molars. In the lower arch, a bite lift was performed on the occlusal surface of mandibular deciduous molars to unblock the occlusion and facilitate the movement of right maxillary central incisor. The total treatment time was 60 days.

Dental Malocclusion and Its Relation to the Podal System.

Background and Objective: This study analyzes the possibility that Stomatognathic and Postural systems are related by muscle chains. Malocclusion may influence the posture, contact between the foot and the ground, center of mass, footprint or vice-versa. This study aimed to verify whether there is a relationship between dental occlusion and podal system.Materials and Methods: A cross-cutting, descriptive study was carried out on 409 children (222 boys and 187 girls) between 8 and 14 years old. Dental occlusion was assessed on the sagittal plane (Angle's classification) the contact between the foot and the ground and the center of mass were evaluated using a stabilometric platform.Results: There was a statistically significant relationship between the plantigrade phase, the contact surface area and center of gravity. There was a prevalence of molar and canine Angle's class II malocclusion. In molar class II, an anterior center of gravity was predominant, in class I it was centered and in class III, it was posterior. There was significant correlation between malocclusions and the FPI (foot posture index) of the left foot and the height of the scaphoid in the right foot (P < 0.001).Conclusions: Some authors agree with our results. There is still much uncertainty in terms of showing a relationship between both systems. In addition, there is scarce scientific evidence on the topic. Some kind of relationship between the two systems has been proven. Studies that evaluate a group of subjects in a longitudinal manner are necessary to enable the changes taking place in both systems to be defined.

Tooth-coloured materials for class II restorations in primary molars: systematic review and meta-analysis.

The aim of this systematic review was to compare the success rate of five tooth-coloured materials, namely Glass Ionomer (GI), Resin-Modified Glass Ionomer (RMGI), Composite Resin (CR), Polyacid-Modified Composite Resin or Compomer (CO) and High-Viscosity Glass Ionomer (HVGI) in primary molar Class II restorations. Five databases were searched from inception to April 23, 2020 for randomized clinical trials comparing the failure rate of these materials. After duplicate study removal, data extraction and risk of bias assessment with the Cochrane tool, data synthesis was conducted, comparing all five tooth-coloured materials in pairs and computing the overall success rate for each one, respectively. A total of 5615 articles were obtained by electronic and hand literature search. After the application of the eligibility criteria, ten RCTs were included in this systematic review and six RCTs for meta-analysis. Their risk of bias was assessed to be high to moderate. Due to the small number of RCTs comparing the five restorative materials in pairs investigated in the same study, only three MAs were available for heterogeneity assessment. These were: (1) between CO-RMGI (RR 1.04 [0.59, 1.84]; p = 0.88; I2 = 1%), (2) CR-CO (RR 1.12 [0.41, 3.02]; p = 0.83; I2 = 57%), and (3) between CR-RMGI (RR 1.10 [0.74, 1.63]; p = 0.65; I2 = 0%). No statistically significant differences were found between the two materials in all three comparisons. CR, RMGI and CO presented no statistical differences. In comparison to other tooth-coloured materials, studies on GI were too few to allow recommendations about its use. More studies on HGVI are needed for evidence-based recommendations to be made. The evidence extracted from this meta-analysis was not strong enough (moderate), due to the small number of RCTs and the risk of bias ranging from high to moderate. More, well-designed RCTs comparing tooth-coloured materials for primary molar Class II restorations are necessary.

The genetic and environmental interaction behind malocclusion: Case report of two twins

Background: Genetic and environmental contribution in the etiology and shape of malocclusion has long been a controversy for the authors. In fact, even though craniofacial deformations are the result of both genetic and environmental factors, there is irrefutable evidence for the high genetic control on craniofacial development and for the significant genetic influence in many dental, occlusal and skeletal variables. The aim of this twin’s case report is to clinically show the role of each of these two factors on the expression of abnormalities and particular traits. Case presentation: The case reflect 10-year-old twins who consulted for their anterior overlap. The comparison between the twins is done through clinical and cephalometric investigation. The clinical examination revealed a great resemblance between the two patients both at the extra-oral (ortho-frontal profil, nasolabial angle, the shape of the forehead, cervico-chin distance) and intra-oral view (Palato- position of the maxillary lateral incisors, molar class I, mandibular arch perfectly identical with mirror effect), Cephalometric analysis revealed a very high morphological similarity (identical skeletal class III, biproalveolia, hyperdivergenc and the position of mandibular incisor). Conclusion: The existence of a very important genetic control on craniofacial development and the installation of dysmorphosis is undeniable, in particular on skeletal class III and hyperdivergence. But the severity of these dysmorphosis can also be increased by environmental and behavioral factors.

Assessment of the mandibular buccal shelf for orthodontic anchorage: Influence of side, gender and skeletal patterns

AbstractObjectivesTo evaluate bone height and thickness in the mandibular buccal shelf region and to compare differences between anatomical sites according to gender, side and vertical and sagittal skeletal patterns.Settings and sample populationMultislice computed tomography (MSCT) images of 94 subjects (51 females and 43 males) were previously obtained as part of preoperative planning for orthognathic surgery.MethodsMeasurements were performed in three different regions of the mandibular buccal shelf: mesially, towards the central groove and distally to the second molars. Bone thickness measurements were obtained perpendicularly 3, 5 and 7 mm below the bone crest towards the mandible outer cortex. Bone height was measured 3 mm away from the bone crest perpendicularly to the outer cortex of the base of mandible.ResultsThere was an increase in bone thickness in the posterior and basal directions. The increase in bone thickness ranged from 1.8 to 7.1 mm. Greater bone height was found in the anterior direction. The increase in bone height ranged from 17.5 to 22.5 mm. Hypodivergent and Class III subjects showed significantly greater bone thickness (P &lt; .05). Significantly greater bone height was found mesially to the second molar in Class III subjects compared with Class I subjects (P &lt; .05) and in hyperdivergent males compared with hypodivergent males (P &lt; .05).ConclusionsThe region distal to the second molar is the most appropriate for the insertion of extra‐alveolar mini‐screws in terms of bone thickness. Hypodivergent and Class III subjects showed greater bone thickness in the mandibular buccal shelf region.

Planejamento interdisciplinar da correção da classe III esquelética com desgastes incisais

This paper shows a case report in which interdisciplinary treatment plan comprised a surgically assisted orthodontic approach previously to the oral rehabilitation in a female, adult patient with dental and skeletal Class III malocclusion and tooth wear. The patient complained about her smile and face aesthetics and the extraoral exam revealed reduced lower lower facial third and absence of upper incisors exposure upper incisor exposure at rest. Intraoral exam exhibited molar and canine Class III relationship, anterior crossbite, tooth wear, shortening of incisors height and reduced occlusal vertical dimension. As treatment results, molar and canine class I relationship was obtained, as well as improvement of the facial proportions and sagittal relation between maxilla and mandible. The surgically assisted orthodontic treatment provided a dental intercuspation favorable to oral rehabilitation, restoring occlusal vertical dimension, reshaping the incisors, and providing occlusion with satisfactory aesthetics and function. This paper demonstrates the importance and necessity of an interdisciplinary approach on the treatment of dental and skeletal Class III malocclusion and clear communication of all the professionals involved.

Condylographic recording of masticatory function: explorative study on occlusal parameters and chewing performance with natural food and a standard food model

Introduction Loss of teeth defines oral health status and chewing abilities. Caries and periodontal disease have been associated with systemic diseases, however they may contribute to cognitive impairment too. Mastication assessment appears to possess broad significance, and is needed to create background knowledge for chewing harmony. The aim of this study was to evaluate chewing performance and the characteristics of condylographic recordings, during mastication of Natural Food (NF) and a Standard Food Model (SFM), in subjects with different occlusal parameters. Methodology Twenty-three adult subjects’ mastication was assessed with a standardized recording protocol, when chewing onto SFM and NF in three different textures. Detailed occlusal characteristics, condylographic recording data and condylographic patterns during mastication were all analyzed and compared. Results Bilateral Crossbites, Missing Molars and Asymmetric Molar Class were related to higher disharmony and transversal displacement during chewing. Missing and unreplaced molars showed dysfunctional patterns and so did worn out occlusal surfaces. Molar Class alone did not prove to be a useful predictor in chewing test results. Conclusion Increasing evidence indicates that oral health has an impact on Individual and Public Health. It is important to understand that oral health and its functional status are to be maintained during one’s lifetime, and that preventive, therapeutic measures at all ages should have a common functional target to grant neurobiological health as well as nutritional goals of Mastication. Further studies are needed to better understand the relevance of additional parameters such as Occlusal Plane Inclination, Curve of Spee, and three-dimensional asymmetries.

Clinical Evaluation of Using Three Different Materials in Primary Molar Class II Restorations

Clinical Evaluation of Using Three Different Materials in Primary Molar Class II Restorations

Dentofacial dysmorphoses : distant links with musculo-skeletal system and posture

According to several theories, the oro-facial sphere would be interconnected with the rest of the body justifying the requests for care to improve a body zone at a distance. The aim of this literature review was to look for potential distant links of dysmorphoses of the three dimensions of space according to the etiopathogenic theories and the data of science. We carried out a keyword search leading to 58 references. In the transverse dimension, the transverse maxillary hypoplasia and dissymmetry of the molar class of the transverse dimension would not induce a change in the distribution of the weight of the body on a stabilometric platform. In the vertical dimension, hyperdivergent patients have a decreased bite force, cephalic extension with respect to the spine, an extension of the base of the skull, and decreased cervical lordosis. In the anteroposterior dimension, skeletal classesII would be associated with increased cervical lordosis and posterior cephalic extension according to the «true vertical» (inversely for classes III). The prevalence of dental classes II would be increased in scoliosis subjects. Studies with a low level of evidence (grade III, IV or even V) should be interpreted with caution because the simultaneous presence of concomitant anomalies does not allow us to conclude that there is a cause-and-effect relationship.

Mandibular border movements: The two envelopes of motion.

The envelope of motion is a diagrammatic representation of the mandibular border movements. Classically, those movements are carried out eccentrically; starting from the position of maximal intercuspation, the mandible describes an excursion movement until reaching maximal mouth opening. Reverse movements would describe a different path, but up to now concentric development of mandibular border movements has not been considered. Literature states that beyond mandibular border movements limits, no movement is possible. Therefore, it is of great interest to compare both paths-both envelopes of motion-and define the actual limits of mandibular movement. The aim of this study was to compare the geometric characteristics of mandibular border movements carried out eccentrically and concentrically by healthy subjects. Sixteen individuals aged between 18 and 27years, molar class I and with no temporomandibular disorders, participated in the study. Eccentric and concentric mandibular movements were recorded using a 3D electromagnetic articulograph. Data were processed with computational scripts developed in MATLAB. Maximum mouth opening, trajectories, displacement ranges, polygon areas and chewing cycle area/ mandibular border movements area ratio were analysed. The frontal plane showed significant differences in all the parameters evaluated. Higher values were registered in the concentric area of the border movement envelope (P=.008) and in the trajectories on both sides. Statistical differences were observed in polygon areas (P=.006) in the sagittal plane and right ranges (P=.046) in the horizontal plane. Concentric mandibular movements revealed significant differences in three-dimensional trajectories in the frontal plane.

Influence of Dental Malocclusion on Body Posture and Foot Posture in Children: A Cross-Sectional Study.

The number of studies that investigate the correlations between the temporomandibular system and body posture, postural control, or the distribution of plantar pressure has recently been increasing. However, most of the existing information is not conclusive. Therefore, the study objective was to evaluate if the features of dental malocclusion are correlated with body posture alterations at the lower limb level. This is a multicentre cross-sectional study with 289 children (8–14 years). Angle’s molar relation was analysed at the dental level. The postural control and the plantar pressure distribution were recorded via a force platform. Correlation and inferential analysis between the Angle class and the foot’s biomechanics were tested. The centre of gravity is anteriorised in Angle’s Class II in both the molar class (p ≤ 0.001) and the canine class (p ≤ 0.001). Likewise, a relationship was observed between the contact surface and Angle’s classes, being higher in class III than in II (p ≤ 0.001). The plantigrade phase is shortened in Angle’s Class III. A relationship was found between Angle’s Class II and a forward movement of the centre of gravity. No relationship was found between the Foot Posture Index and the truncated scaphoid height and the dental classification. An evident relationship between the gait typology and dental malocclusion was not found.

Buccolingual Inclination of Canine and First and Second Molar Teeth and the Curve of Wilson in Different Sagittal Skeletal Patterns of Adults Using Cone-Beam Computed Tomography.

Objectives This study aimed to assess the buccolingual inclination of canine and first and second molar teeth and the curve of Wilson in different sagittal skeletal patterns in untreated adults using cone-beam computed tomography (CBCT). Materials and Methods Sixty-six CBCT scans of adults (mean age: 28.74 ± 5.25 years) were evaluated in this cross-sectional study. The images were standardized using the Frankfurt horizontal plane and the interorbital line. The sagittal skeletal pattern was determined using the ANB angle and Wits appraisal. Inclination angles were measured by NNT Viewer and Mimics software. The curve of Wilson was measured by connecting the tips of mesiobuccal and mesiolingual cusps of maxillary first and second molars along the buccal groove and measuring the formed angle. Data were analyzed using ANOVA. Results The intraobserver agreement was 0.969. The mean inclination of maxillary first and second molars in class I and III patients was significantly higher than that in class II patients (P < 0.05). The mean inclination of mandibular first and second molars in class II patients was significantly higher than that in class I and III patients (P < 0.05). The difference in inclination of maxillary and mandibular canine teeth was not significant (P > 0.05). The mean curve of Wilson in second molars of class II patients was significantly higher than that in class I patients (P < 0.05). Conclusion In different sagittal skeletal patterns, a compensatory relationship exists between the opposing teeth, which, along with the standards of crowns, can be used to determine the appropriate position of teeth in dental arch.

Malocclusion Prevalence in 6 to 12 years old children in the city of Coronel Oviedo, Paraguay, 2016

Malocclusions, according to the World Health Organization (WHO), rank third as oral health problems. The aim of this research work was to determine the frequency of malocclusion present in 6 to 12 years old children in the city of Coronel Oviedo, Paraguay in 2016.A descriptive observational study with analytic component was performed in the children that had the first permanent upper and lower molar in at least one hemiarch, who presented the informed consent signed by the parents. The outcomes were malocclusion, molar and canine relation, overjet and overbite, crowding and crossbite. The data was loaded into an Excel spreadsheet and analyzed with the Stata 14 program. Malocclusion was found in 66% of the children, 85.7% presented molar and canine Class I, 44.6% normal overbite, 35.7% normal overjet, 55.4% crowding, 8.9% presented crossbite, 75% straight profile, 62.5% deviation from the midline. In relation to age (p=3.2) and sex (p=0.4), no statistically significant associations were found in relation with malocclusion. The frequency of malocclusion in schoolchildren from Coronel Oviedo, Paraguay was high

Mesial Rotation of the Upper First Molar: Association with Anterior Dental Crowding in Mixed and Permanent Dentition

The position of the upper first molar (UFM) is currently considered the “key of occlusion”. The purpose of this study was to evaluate the prevalence of the mesiorotated UFM, and its relationship with anterior dental crowding in mixed and permanent dentition. Intra-oral scans of upper dental arches of 180 subjects with mixed dentition and 169 subjects with permanent dentition were retrospectively analyzed to investigate the presence of UFM mesiopalatal rotation and presence of anterior crowding. The occlusal relationship and the presence of caries were also recorded. In subjects with permanent dentition, there was a statistically significant correlation between anterior crowding and UFM mesiopalatal rotation (Pearson’s chi-square = 9.03; p = 0.06). Among cases with permanent dentition, subjects with UFM mesiopalatal rotation showed an OR = 3.28 (95% CI = 0.99–10.93; p = 0.042) of moderate/severe anterior dental crowding, respect to subjects without UFM rotation. In subjects with mixed dentition, there was a statistically significant correlation between molar occlusal relationship and UFM mesiopalatal rotation (Pearson’s chi-square = 14.98; p = 0.002), and subjects with molar class II showed a OR = 10.2 (95% CI = 2.16–48.22; p = 0.0005) to present UFM mesiopalatal rotation, with respect to subjects with molar class I. UFM mesiopalatal rotation is associated to anterior dental crowding in permanent dentition, and to class II malocclusion in mixed dentition.

Types and frequency of body postures and dental malocclusions

The jaw is articulated with the skull through the temporomandibular joint. And the skull, in turn articulates with the spine (upper cervical). Important studies establish that up to 30-40 % of back pain can be caused or aggravated by dental malocclusion. Objective. To establish the types and frequency of body postures and dental malocclusions in the patients of the School of Dentistry in the period August-December 2019. Methodology. Transversal, descriptive and observational study. The sample was made up of a total of 50 patients between the ages of 19 and 70 who attended the Admission Clinic of the School of Dentistry. To which were carried out: verification of molar class, verification of midline deviation, verification of posterior crossbite, external lateral palpation of the TMJ, extraoral photographs, analysis of photographs. Contribution. It was found that there is a high frequency of one type of body posture and Angle Class I malocclusions, in patients from the School of Dentistry. In relation to malocclusions, Angle Class I predominated, as well as flattened posture, in Class II military posture and in Class III both flattened and military posture.

Nahoum Index in Brachyfacial Patients: A Pilot Study.

Our aim is to test the Nahoum Index as a support in the cephalometric study of vertical dimension and therapeutic orientation in adult patients suffering from Class II malocclusion, deep bite, or short face syndrome. Twenty-three patients with molar Class II and an overbite >4 mm were stratified into two groups: orthodontic (G2) and surgical orthodontic (G1). The ANB angle and Nahoum Index were calculated for cephalometric tracing pre- and post-treatment. The difference between the ANB and Nahoum Index values were analyzed using the Statistical Package for the Social Sciences software. In G1, the Nahoum Index decreased from 0.954 to 0.797, and the ANB angle decreased from 5.2° to 3.2°. In G2, the Nahoum Index decreased from 0.825 to 0.817, and the ANB angle decreased from 4.4° to 4°. In G1, the difference between before and after treatment was significant for the Nahoum Index only. The difference between before and after values was not significant in the G2 group. It is possible to indicate the Nahoum Index of 0.934 as the limit value in case of which a patient may be treated with orthodontics only. This limit is the opposite of the limit proposed by Nahoum for vertical excess cases and respect the same interval. Therefore, we can consider the range 0.81-0.934 to indicate borderline patients, and >0.934 to indicate surgical patients. If the ratio is close to the normal value as 0.81, the treatment will be orthodontic; if it is further increased, the treatment will be surgical.

Cranial Facial 3D Biometry: Statistical analysis of Class II disharmonies

We could study Cone Beam documents of patients consulting in ORL with standard Angle Class I occlusion (45 ND), patients consulting in orthodontics with an orthodontic Class II (51 APNS) and patients with a surgical Class II (83 APS). The used 3D biometry calculates systematically a 164 set of parameters able to take into account all kinds of disharmonies; among which 38 parameters are specifically devoted to anterior-posterior "off asymmetry" pathologies. Then the specific Artificial Intelligence (AI) programs treat morphological data and give textual diagnoses. Analysis of the global sample aims to control the efficiency, separating different sub-samples one each other: t test appreciates efficiency of each parameter to recognize clinical sub-sample. The correlation coefficient, r, between each parameter and pseudo Angle molars Class II (GMMy-Gmmy) give the importance of its tie with Class II pathology. Presentation of parameters medium values in each sub-group gives the medium profiles. By direct comparison of patient's parameters values with medium profile, it is possible to locate patient's pathology. So we can take in account new parameters like arches upper/lower gap, anterior bases upper/lower gap, compensatingparameters... It is then possible to make more secure the clinical decision.

Comparison of Microleakage of Self-etch and Total-etch Bonding Agents in Primary Molar Class II Composite Restorations

Introduction: This study evaluated microleakage of flowable and conventional composite in primary molar class II restorations using self-etch and total-etch bonding agents. Methods: Class II standard cavities were prepared on proximal surface of 48 primary molars. These cavities were restored using GrandioFlow and Grandio composites and Futurabond DC and Solobond M as bonding agents. Teeth apices were sealed by wax and two-layer nail varnish was applied up to 1mm of restoration margins. Samples were subjected to thermocycling, stained by silver nitrate solution and sectioned mesiodistally. Microleakage was measured from the tooth-restoration margin to end point of dye penetration using a stereomicroscope with a 0-3 scale. Microleakage scores were analyzed using Kruskal-Wallis test in 4 groups and paired comparisons were performed using Monte Carlo test. Results: Microleakage was seen in all composite and bonding agent groups. Pairwise comparison showed no significant difference regarding the microleakage between groups ( P>0.05) . Conclusion: Gradioflow as a flowable composite and Futurabond DC as a self-etch bonding agent both showed acceptable results in regard to microleakage. Considering the ease of application of flowable composites compared to conventional ones and shortening the treatment both flowable composites and self-etch bonding agentshave showed promising results in pediatric dentistry