Occlusal Curvature Research Articles

Comparative evaluation of buccolingual inclination of molars in low-angle cases and high-angle cases using manual technique- A pilot study

The general feature of occlusal curvature, when viewed from the front, consists of a buccal inclination of the maxillary molars and a lingual inclination of the mandibular molars. The fourth key of Andrew’s six keys of occlusion is related to the curve of Wilson, describing the posterior inclination of the crowns of the lower posterior teeth as a concave curve, setting the molars with a lingual torque. Facial skeletal characteristics of subjects with a vertical growth pattern include increased total face height, especially the lower anterior face height, high mandibular plane angle, clockwise mandibular rotation, short mandibular ramus, and high gonial angle. Opposite aspects are present in subjects with a horizontal growth pattern. This study aimed to measure the buccolingual inclination of maxillary first molars in low-angle and high-angle cases using a manual technique. 20 subjects with permanent dentition were divided into 2 groups. Group I comprises 10 subjects with a low-angle case (proportionally short lower anterior facial height) and group II with a high-angle case (proportionally long lower anterior facial height). The buccolingual inclination of 1st molar was assessed on model casts.The maxillary posterior teeth of subjects with a vertical growth pattern (group II) had a significantly greater buccal inclination compared with those of subjects with a horizontal growth pattern (group I).

Correlation between Depth of the Curve of Spee and Some Specific Malocclusion Characteristics in a Population from Sibiu County, Romania-A Cross-Sectional Study.

Background: This study aimed to investigate the relationship between the Curve of Spee (COS) depth and malocclusion characteristics in a population from Sibiu County, Romania. The research sought to understand how the COS's anatomical dimensions correlate with different classes of malocclusion and the position of the frontal teeth. Methods: A total of 265 participants from the Dentistry Ambulatory of the Military Hospital of Sibiu were included in this study. It employed digital intraoral scanning technology to measure the COS, overjet, and overbite, with malocclusion classification. Statistical analyses, including correlation and regression, were conducted to examine the relationships between COS depth, frontal teeth position, and malocclusion characteristics. Results: The average COS depth measured was 1.0564 mm, presenting variability when compared to existing literature. Most of the study participants had Class I malocclusion. A significant positive correlation between COS depth and overjet was identified, with no notable gender-based differences in these occlusal parameters. Conclusions: The findings affirm the integral role of COS in occlusal dynamics and malocclusion diagnosis. The COS measurement of a mean of 1.0564 mm, when compared to other results emphasizes the differences in occlusal curvature among various populations. The results contribute to a refined understanding of occlusal relationships, supporting the need for personalized orthodontic and prosthetic treatments based on precise anatomical measurements.

Variability in depth of curve of Spee and its associated skeletal and dental implications in population of Pakistan

Background and Aim: The curve of Spee (COS) is a physiological entity in human dentition. A functional masticatory system necessitates an appropriate occlusal curvature. The primary objective of this investigation was to assess the skeletal and dental parameters in individuals with variation in the depth of curve of Spee. Materials and Methods: A total of 276 patients with pre-treatment lateral cephalograms and dental cast models were investigated in the Orthodontics and Dentofacial Orthopedics Unit of a Tertiary Care Hospital of Mardan, Pakistan from January 2021 to December 2022. Patients with no prior history of orthopedic treatment for functional jaw, prosthodontic treatment, no prior history of cleft lip and palate and cranio-facial disorders were enrolled. Ethical approval was obtained and all the patients were categorized into three groups based on the depth of curve of Spee (COS): Group-I (flat curvature < 2 mm), Group-II (normal curvature 2-3 mm), and Group-III (deep curvature > 3 mm). Lateral cephalometric analysiswas done to measure the four angular and four linear parameters. Molar relation, overbite, COS depth, and overjet were measured based on the occlusal classification. SPSS version 27 was used for data analysis.

The Effect of Accentuation of Curve of Spee on Masticatory Efficiency—A Systematic Review and Meta-Analysis

The appropriate alignment of the lower teeth is indicated by the Curve of Spee (COS), which can be observed in the sagittal profile view of human skulls. Graf Von Spee made the initial observation on this occlusal curvature. Through this systematic review and meta-analysis, we evaluated studies that looked at how COS affected masticatory activities. The databases PubMed-MEDLINE, Web of Science, Cochrane, and Scopus were all searched. A total of 12 documents were ultimately picked because they met the necessary inclusion and exclusion requirements. The data was then loaded into the RevMan 5 programme for meta-analysis after being chosen for information on the sample size, variables analyzed, and various aspects of the research. The Curve of Spee was found to have a noticeable impact on both the masticatory efficiency as well as dentofacial alignment in the 12 studies that we selected for the review and meta-analysis. In addition, other occlusal curvatures such as the Curve of Monson and the Curve of Wilson were found to be of vital importance on a similar level to the COS. The meta-analysis further revealed that seven of the included clinical trials had mentioned the noticeable impact on masticatory efficiency. This study focused on the significance of the COS on force distribution in the oral cavity as well as the necessity of COS corrections after receiving full orthodontic care. Following orthodontic treatment, the COS, along with other occlusal curves such as the Curve of Wilson and the Curve of Monson, is essential in removing strains from the condyle, as well as the maxilla and mandible, which enhances masticatory effectiveness and lessens the overall strain on a patient's oral cavity.

Relationship between the Morphology of Maxillofacial Skeletons and Occlusal Curvature

Relationship between the Morphology of Maxillofacial Skeletons and Occlusal Curvature

Evaluation of the curve of Spee, curve of Wilson and Monson’s sphere in Iranian adults: A preliminary three-dimensional study

Purpose : One of the required information in rehabilitating the occlusal plane in dentistry is the radius of Monson’s sphere , which like other anatomical indices varies in different races. The purpose of this study was to determine the radius of the Monson’s sphere in a group of Iranian. Materials & Methods : 45 Iranian subjects (19 males & 26 females ) aged from 18 to 25 were selected for this study . The x,y,z coordinates of cusp tips of all mandibular teeth except for the third molars obtained with a 3-dimensional digitizer , were used to derive a spherical model of the occlusal surfaces’ curvature . From the best interpolating sphere , the radii of the Monson’s sphere was computed . Results : Although all of the computed variables were greater in men , the occlusal curvature of mandibular arch was not influenced by gender . The mean radius of the Monson’s sphere was 111.5 mm ( 121 mm in men and 104 mm in women which was closer to the classic value of 4 inch , confirming Monson’s observations ) . Conclusion : The average radius of the Monson’s sphere in this study was greater than the classic 4 inch value proposed by Monson and this result may suggest racial differences in the normal dental arch form that is important in occlusal rehabilitation. Although more researches are necessary in future to improve treatment results.

Development of the mandibular curve of spee and maxillary compensating curve: A finite element model.

The curved planes of the human dentition seen in the sagittal view, the mandibular curve of Spee and the maxillary compensating curve, have clinical importance to modern dentistry and potential relevance to the craniofacial evolution of hominins. However, the mechanism providing the formation of these curved planes is poorly understood. To explore this further, we use a simplified finite element model, consisting of maxillary and mandibular “blocks”, developed to simulate tooth eruption, and forces opposing eruption, during simplified masticatory function. We test our hypothesis that curved occlusal planes develop from interplay between tooth eruption, occlusal load, and mandibular movement. Our results indicate that our simulation of rhythmic chewing movement, tooth eruption, and tooth eruption inhibition, applied concurrently, results in a transformation of the contacting maxillary and mandibular block surfaces from flat to curved. The depth of the curvature appears to be dependent on the radius length of the rotating (chewing) movement of the mandibular block. Our results suggest mandibular function and maxillo-mandibular spatial relationship may contribute to the development of human occlusal curvature.

The frugivorous insectivores? Functional morphological analysis of molar topography for inferring diet in extant treeshrews (Scandentia)

AbstractThe ecology, and particularly the diet, of treeshrews (order Scandentia) is poorly understood compared to that of their close relatives, the primates. This stems partially from treeshrews having fast food transit times through the gut, meaning fecal and stomach samples only represent a small portion of the foodstuffs consumed in a given day. Moreover, treeshrews are difficult to observe in the wild, leading to a lack of observational data in the literature. Although treeshrews are mixed feeders, consuming both insects and fruit, it is currently unknown how the relative importance of these food types varies across Scandentia. Previous study of functional dental morphology has provided an alternative means for understanding the diet of living euarchontans. We used dental topographic metrics to quantify aspects of functional dental morphology in a large sample of treeshrews (n = 58). We measured relief index, Dirichlet normal energy, and three-dimensional orientation patch count rotated, which quantify crown relief, occlusal curvature, and complexity, respectively. Our results suggest that treeshrews exhibit dental morphology consistent with high levels of insectivory relative to other euarchontans. They also suggest that taxa such as Dendrogale melanura and Tupaia belangeri appear to be best suited to insectivory, whereas taxa such as T. palawanensis and T. gracilis appear to be best adapted to frugivory. Our results suggest that Ptilocercus lowii is characterized by a dentition better adapted to insectivory than the early primate Purgatorius. If P. lowii represents a good modern analogue for primitive euarchontans, this contrast would support models of primate origins that include a shift to greater frugivory.

Three-dimensional analysis of tooth movement in Class II malocclusion treatment using arch wire with continuous tip-back bends and intermaxillary elastics.

ObjectiveThe aim of this study was to analyze three-dimensional (3D) changes in maxillary dentition in Class II malocclusion treatment using arch wire with continuous tip-back bends or compensating curve, together with intermaxillary elastics by superimposing 3D virtual models.MethodsThe subjects were 20 patients (2 men and 18 women; mean age 20 years 7 months ± 3 years 9 months) with Class II malocclusion treated using 0.016 × 0.022-inch multiloop edgewise arch wire with continuous tip-back bends or titanium molybdenum alloy ideal arch wire with compensating curve, together with intermaxillary elastics. Linear and angular measurements were performed to investigate maxillary teeth displacement by superimposing pre- and post-treatment 3D virtual models using Rapidform 2006 and analyzing the results using paired t-tests.ResultsThere were posterior displacement of maxillary teeth (p < 0.01) with distal crown tipping of canine, second premolar and first molar (p < 0.05), expansion of maxillary arch (p < 0.05) with buccoversion of second premolar and first molar (p < 0.01), and distal-in rotation of first molar (p < 0.01). Reduced angular difference between anterior and posterior occlusal planes (p < 0.001), with extrusion of anterior teeth (p < 0.05) and intrusion of second premolar and first molar (p < 0.001) was observed.ConclusionsClass II treatment using an arch wire with continuous tip-back bends or a compensating curve, together with intermaxillary elastics, could retract and expand maxillary dentition, and reduce occlusal curvature. These results will help clinicians in understanding the mechanism of this Class II treatment.

Validity on the Study Models of Dental Simulation Training: Focus on the Dental Arch and Occlusal Curvature

Validity on the Study Models of Dental Simulation Training: Focus on the Dental Arch and Occlusal Curvature

Occlusion, prosthodontic treatment, and temporomandibular disorders: a review.

The purpose of this article is to review the literature on the relationship between occlusal discrepancies and temporomandibular disorders (TMD) and to summarize the guidelines of treating TMD by prosthetic rehabilitation. To date, the relationship between occlusal condition and TMD has not been confirmed, although there is a current trend toward making a weak correlation between occlusal interference and TMD. Furthermore, several types of occlusal discrepancies have been considered as variable features of the norm. But unstable occlusion in the intercuspal position may cause TMD. In cases of restored dentition, the problem is probably different and iatrogenic TMD are not rare. Namely, malformed occlusal surfaces, defects in anterior guidance, occlusal curvature, and vertical dimension may lead to some TMD trouble. According to these recent concepts the treatment modalities of TMD have been changed. Conservative treatments such as counseling, behavioral modification, physical therapy, pharmacotherapy, and interocclusal appliances should be the first choice, and treatments that lead to drastic changes of occlusion are not recommended.

교합면의 해부학적 형태와 교합만곡의 연관성에 대한 연구

교합면의 해부학적 형태와 교합만곡의 연관성에 대한 연구

Curve of spee: a literature review

The curve of Spee (COS) is an important characteristic of the dental arch that was described as an occlusal curvature seen in the sagittal plane. This natural phenomenon has clinical importance in orthodontics and restorative dentistry. This study aim to gather the current knowledge of COS in order to become a guide for a construction of an optimal occlusion. The methodology utilized was a review and compilation of the most pertinent literature articles. The following were deliberated in this review: development, measurement, evolutive similarities, gender, side, properties, the purpose of levelling, the sorts of levelling and the long-term stability of the COS. In conclusion, although a large amount of research on COS already exists, there is no standard methodology to define an ideal model of treatment and/or prevention. Nevertheless, its results give dentists a complete overview to establish their approach towards a successful long-term stability treatment.

Surfaces and spaces: troubleshooting the study of dietary niche space overlap between North American stem primates and rodents

Dental topographic metrics provide quantitative, biologically meaningful data on the three-dimensional (3D) form of teeth. In this study, three dental topographic metrics (Dirichlet normal energy (DNE), relief index (RFI), and orientation patch count rotated (OPCR)) are used to evaluate the presence of dietary niche overlap between North American plesiadapoid primates (Plesiadapidae, Carpolestidae, and Saxonellidae) and early rodents. Calculation of these metrics requires researchers to modify the 3D surface models of the teeth by cropping them to a region of interest and/or orienting them. The current study therefore also examines the error introduced by cropping and orientation, and evaluates the contribution of these metrics to the niche overlap hypothesis. Our results indicate that cropping creates significantly more variation in RFI than DNE. Furthermore, orientation is an even larger source of variation in the calculation of RFI than cropping. Orientation does not strongly influence OPCR values. However, none of these sources of error are significant enough to undermine the extent to which these metrics can speak to the niche overlap hypothesis. The DNE and RFI results suggest that carpolestids and saxonellids had very different molar morphologies from early rodents, and thus these groups were not adapted to consume the same resources. Some plesiadapids show similar levels of occlusal curvature, relief, and complexity to early rodents. The plesiadapid Chiromyoides, which has distinctively low cusps and weak shearing crest development, has molars that are the most rodent-like of all taxa compared. This suggests that Chiromyoides had a dietary niche that overlapped with early rodents and would have been the most likely to be competing over food resources. Results from the plesiadapoid-rodent dental topographic analysis highlight the utility of DNE for detecting more fine-scaled differences in occlusal surface morphology than OPCR, whereas RFI provided valuable data on the degree to which teeth were high crowned.

Analysis of the curve of Spee and the curve of Wilson in adult Indian population: A three-dimensional measurement study.

Statement of Problem:When reconstructing the occlusal curvatures dentists often use a 4-inch radii arc as a rough standard based on Monson spherical theory. The use of an identical radius for the curve of Spee for all patients may not be appropriate because each patient is individually different. The validity of application of this theory in the Indian population and the present study has been undertaken.Aims and Objectives:This study is an attempt to evaluate the curve of Spee and curve of Wilson in young Indian population using three dimensional analysis. This study compared the radius and the depth of right and left, maxillary and mandibular curves of Spee and the radius of maxillary and mandibular curves of Wilson in males and females.Materials and Methods:The cusp tips of canines, buccal cusp tips of premolars and molars and palatal/lingual cusp tips of second molars of 60 maxillary and 60 mandibular casts were obtained. Three-dimensional (x, y, z) coordinates of the cusp tips of the molars, premolars, and canines of the right and left sides of the maxilla and mandible were obtained with three dimensional coordinate measuring machine. The radius and the depth of right and left, maxillary and mandibular curves of Spee and the radius of maxillary and mandibular curves of Wilson were measured by means of computer software Metrologic-XG. Pearson's correlation test and Independent t-test were used to test the statistical significance (α=.05).Conclusion:The values of curve of Spee and curve of Wilson in Indian population obtained from this study were higher than the 4 inch (100 mm) radius proposed by Monson. These findings suggest ethnic differences in the radius of curve of Spee and curve of Wilson.

Evaluation of the relationship between curve of Spee and dentofacial morphology in different skeletal patterns

Background: Curve of Spee (CS) is an anteroposterior anatomical curve established by the occlusal alignment of the teeth viewed in the sagittal plane. This occlusal curvature has clinical importance in orthodontics and other fields of dentistry. This study aimed to evaluate the relationship between the CS and dentofacial morphology of different skeletal patterns in both genders. Materials and Methods: Eighty six Iraqi Arab subjects (44females,42 males ) their age ranged from 17 -30 years, classified into: Skeletal I with normal occlusion(15 females and 15 males), skeletal II with CI II div 1 malocclusion (15 females and 15 males) and skeletal III with CI III malocclusion (14 females and 12 males). Forty one variables measured using direct dental cast measurements , dental cast photographs and cephalometric radiographs with the aid of AutoCAD program version 15 (2006). Results: No significant differences in the CS depth between males and females or between right and left sides in both arches of different skeletal patterns. No significant differences in the maxillary CS among the 3 skeletal patterns, the mandibular CS in CI II div 1 malocclusion was larger than normal occlusion and CI III malocclusion. Maxillary CS significantly correlated to arch length, inter canine distance and inter second premolar distance in normal occlusion and overbite in Cl III malocclusion. Mandibular CS significantly correlated with overbite and overjet in Cl II div 1 and Cl III malocclusions. Conclusions: CS was not influence by sides and gender in both arches of different skeletal patterns. CS was concave in the mandibular arch with the maximum concavity at the mesio-buccal cusp tip of the mandibular first molar and convex in the maxillary arch with the maximum convexity at the buccal cusp tip of the maxillary second premolar, in different skeletal patterns. Key words: Curve of Spee, arch length, overbite, overjet, dentofacial morphology.

乱れた咬合平面を有する歯列欠損患者の補綴

乱れた咬合平面を有する歯列欠損患者の補綴

The role of occlusal curvatures and maxillary arch dimensions in patients with signs and symptoms of temporomandibular disorders

To identify differences in occlusal curvatures and maxillary arch dimensions between subjects with signs and symptoms of temporomandibular disorders TMDs and asymptomatic subjects. One hundred subjects 78 female and 22 male who consented to participate in this research were examined for signs and symptoms of TMDs according to the guidelines of the Research Diagnostic Criteria for Temporomandibular Disorders RDCTMD. In addition, occlusal measurements were performed for all subjects on plaster models. All statistical analyses were performed with SPSS version 19. Significant associations were revealed between the depth of the curve of Spee COS and temporomandibular joint TMJ sounds. Furthermore, maxillary arch width was negatively correlated to the steepness of the curve of Wilson. No differences were found between subjects with and without a history of orthodontic treatment. Subjects with TMJ sounds tend to have a flatter COS compared to subjects without TMJ sounds.

Making three-dimensional Monson's sphere using virtual dental models

ObjectivesThe Monson's sphere and curve of Wilson can be used as reference for prosthetic reconstructions or orthodontic treatments. This study aimed to generate and measure the three-dimensional (3-D) Monson's sphere and curve of Wilson using virtual dental models and custom software. MethodsMandibular dental casts from 79 young adults of Korean descent were scanned and rendered as virtual dental models using a 3-D digitizing scanner. 26 landmarks were digitized on the virtual dental models using a custom made software program. The Monson's sphere was estimated by fitting a sphere to the cusp tips using a least-squares method. Two curves of Wilson were generated by finding the intersecting circle between the Monson's sphere and two vertical planes orthogonal to a virtual occlusal plane. Non-parametric Mann–Whitney and Kruskal–Wallis tests were performed to test for difference between sex and in cusp number within tooth position. ResultsThe mean radius of Monson's sphere was 110.89±25.75mm. There were significant differences between males and females in all measurements taken (p<0.01), within 16.87–17.27mm. Furthermore, morphological variation derived from variability in cusp number in the second premolar and second molar were not found to influence occlusal curvature (p>0.05). ConclusionsThis study describes a best-fit algorithm for generating 3-D Monson's sphere using occlusal curves quantified from virtual dental models. The radius of Monson's sphere in Korean subjects was greater than the original four-inch value suggested by Monson. Clinical significanceThe Monson's sphere and curve of Wilson can be used as a reference for prosthetic reconstruction and orthodontic treatment. The data found in this study may be applied to improve dental treatment results.

Association between occlusal curvature and masticatory movements with different test foods in human young adults with permanent dentitions

ObjectiveOcclusal curvatures such as the curve of Spee, curve of Wilson and Monsons's sphere exist in the human adult mandibular arch. A previous study showed that human young adults with flatter occlusal curvatures had higher ability of food comminution and mixing. The aim of this study was to clarify functional significance of occlusal curvatures in terms of masticatory movements. This study investigated the association between occlusal curvature and mandibular movements while chewing a variety of food items. DesignForty-six young adults with complete dentitions (mean age, 25.0 years) participated in the study. Sphere radius of occlusal curvature was determined by a three-dimensional analysis of the mandibular arch based on the Broadrick flag method. Mandibular movements during unilateral chewing of six test food items (chewing gum, cheese, kamaboko, boiled beef, gummy jelly and raw carrot) until the subjects felt ready to swallow were recorded using a six-degrees-of-freedom mandibular movement recording system, and 11 parameters for masticatory movements of a lower incisal point of the mandible were analysed. ResultsLinear regression analyses identified the sphere radius as a significant predictor for closing velocity in all test food items, occluding/cycle duration in 3 items, opening velocity, closing duration and chewing time in 2 items, and opening duration in 1 item (P<0.01). The results suggest that subjects with larger sphere radius (flatter occlusal curvature) in the mandibular arch could prepare food bolus effectively for swallowing. ConclusionOcclusal curvature seems to be associated with masticatory movements in young adults with permanent dentition.