Knowledge-dependent pattern classification of human nasal profiles

Relationship of Nasal Morphology With Different Dentoskeletal Patterns: A Systematic Review

Introduction:

The nose is considered by some clinicians as the keystone of facial aesthetics. A treatment plan can be customized to intensify the facial aesthetics of a patient through careful evaluation of the soft tissue drape. Hence, for getting a better outcome of the treatment plan, orthodontists are supposed to have in-depth knowledge and awareness of soft tissue changes, taking into notice the ethnic and racial variation in discrete cohorts. The objective of this study is to enlist the relationship of nasal morphology with different dentoskeletal (sagittal and vertical) patterns.

Materials and Methods:

A comprehensive electronic database search was performed till July 2020, of Cochrane Library, Embase, PubMed, Scopus, Google Scholar, Web of Science, Wiley Online Library, and ScienceDirect. Only articles published in the English language were included. After excluding all the irrelevant data through careful screening, a total of 15 articles were selected which discussed the nose–dentoskeletal pattern relation.

Results and Conclusion:

The nose is found to be convex in skeletal class II, straight in class I, and concave in class III. Those with increased vertical growth may have an increased tendency of a convex nasal dorsum. Maxillary and mandibular jaw length affect the nasal parameters more than the jaw position. Nasal length and nasal depth increase with the jaw length and mandibular and maxillary/palatal-plane inclination to the cranium. A long nose with increased nasal depth is expected in long faces and those with long upper and lower jaws. An upturned nose is found with an anticlockwise-rotated maxilla.

Sexual dimorphism in the facial morphology of adult humans: A three-dimensional analysis

The objective of this study was to demonstrate sexual dimorphism in the entire three-dimensional facial surface form of adult humans. The sample consisted of female and male groups (n=200; age range, 18-35 years). Three-dimensional images of each participant's face at rest were recorded. A total of 185 variables that described facial surface configuration features were extracted from each image. The variables were compared between the groups using t-tests, and those exhibiting P-values <0.0001 were entered into a stepwise discriminant function analysis for sex determination. Wire mesh fitting was also performed on each image to examine the facial surface morphology. The mean node coordinates of the fitted mesh were compared between the groups using t-tests. Sixty-seven of the 185 variables differed significantly between the groups, and 11 qualified for inclusion in the stepwise analysis. The female group exhibited a greater vertical height of the eye fissure, shorter postero-anterior height of the nasal tip, vertically greater supraorbital ridge, shorter lower face height relative to the total upper anterior face height, more prominent cheeks in the infraorbital region, less prominent cheeks in the buccal region, shorter vertical height of the subnasal region, a smaller nasal hump, and a smaller alar. The discriminant function analysis was 96.5% accurate overall. The wire mesh fitting results showed that the eyes, forehead, and chin were in vertically higher positions in the female group than in the male group. The cheeks and nose were more protuberant in the female group and male group, respectively.

Objective classification of nose-lip-chin profiles and their relation to dentoskeletal traits

OBJECTIVES

To objectively classify the nose-lip-chin profiles of adult women and identify any associations between the nose-lip-chin profile patterns and dentoskeletal patterns.

SETTING AND SAMPLE POPULATION

Lateral facial photographs and lateral cephalograms were obtained for 229 Japanese women who were being assessed for orthodontic treatment.

METHODS

A feature vector that was effective in distinguishing differences in nose-lip-chin profiles was extracted for each photograph. To categorize the records into an optimum number of subclasses according to nose-lip-chin profile configurations, a vector quantization method was applied to the feature vectors of all samples. Dentoskeletal patterns that corresponded to the nose-lip-chin profile subclasses were compared.

RESULTS

Eight profile patterns were identified, and the differences among patterns were notably maximized by the nasolabial angle, configuration and vertical length of the subnasal region, vertical thickness of the lip vermilion borders, sagittal position of the upper- and lower-lip vermilion borders and their relation to each other, labiomental angle, depth of the labiomental sulcus, degree of prominence of the chin, and degree of protrusion of the mandible. The dentoskeletal patterns showed significant differences between the classified profile patterns (p < 0.01).

CONCLUSIONS

A method to objectively classify the nose-lip-chin profiles of adult women was established, and the nose-lip-chin profile patterns were found to be associated with the dentoskeletal patterns.

Objective three-dimensional assessment of lip form in patients with repaired cleft lip

OBJECTIVES

To measure and compare three-dimensional lip form in participants with a repaired cleft lip and noncleft control participants.

DESIGN

Retrospective study. Three-dimensional facial images of each participant were obtained.

PARTICIPANTS

The sample consisted of two groups: a repaired cleft lip group (n  =  57) and a noncleft "normal" group (n  =  28).

MAIN OUTCOME MEASURES

Thirty-four variables that described the features of each participant's lip form were extracted from the image data. A t test was used for each variable to test for significant differences between the groups, and a mathematical technique was used to categorize the lip forms in both groups.

RESULTS

Seventeen variables showed significant between-group differences. The differences were focused on the free edges of the upper and lower lip vermilion borders, upper and lower lip protrusion, and lip symmetry. Lip forms were described by seven categories. Participants with cleft lip were represented in all categories but fell mainly into two categories at one extreme. Noncleft participants were represented in five categories but also exclusively in two categories at the other extreme from participants with a repaired cleft lip. The findings show greater variation in lip form for the participants with a cleft lip.

CONCLUSION

Three-dimensional lip form in participants with a repaired cleft lip was found to have greater variation and to be significantly different from that in noncleft participants. This method can be used to assess surgical outcomes of lip form.

Computational formulation of orthodontic tooth-extraction decisions. Part I: to extract or not to extract

OBJECTIVE

To develop a mathematical model that simulates whether or not to extract teeth in optimizing orthodontic treatment outcome and to formulate the morphologic traits sensitive to optimizing the tooth-extraction/nonextraction decisions.

MATERIALS AND METHODS

A total of 188 conventional orthodontic records of patients with good treatment outcomes were collected, and dentofacial morphologic traits, along with their degrees of influence in the optimized model, were determined.

RESULTS

The rate of coincidence between the recommendations given by the optimized model and the actual treatments performed was found to be 90.4%. The major morphologic traits and their corresponding influences in improving the simulation accuracy of the model were the incisor overjet (3.0) and the size of the basal arch relative to the sum of the mesiodistal crown diameters of the upper dentition (2.4) and the lower dentition (2.0). The remaining 22 morphologic-trait variables were also found to be indispensable in achieving robust simulation readings.

CONCLUSION

A mathematical model that simulates whether or not to extract teeth in optimizing orthodontic treatment outcomes with a success rate of 90.4% at its prediction performance was developed. This model has 25 morphologic traits with four major categories (sagittal dentoskeletal and soft tissue relationship, vertical dentoskeletal relationship, transverse dental relationship, and intra-arch conditions) that affected the accuracy in determining optimal tooth extractions/nonextractions.

Lip vermilion profile patterns and corresponding dentoskeletal forms in female adults

OBJECTIVES

To objectively classify shapes of the human lip vermilion in the lateral view, and to examine whether any morphologic characteristics of dentoskeletal patterns are specific to each classified lip profile pattern.

MATERIALS AND METHODS

Pretreatment, lateral facial photographs of 234 Japanese women were selected. Investigators with expert knowledge of the anatomic traits of the lip vermilion in the lateral view extracted from images of the face a 13-dimensional feature vector that represented lip vermilion profile shapes. The vector quantization technique was applied to the feature vectors to mathematically optimize the number of lip vermilion profile patterns. Dentoskeletal patterns that corresponded to each classified lip shape were compared statistically.

RESULTS

Seven patterns were found, and differences between patterns were notably maximized by the flatness of the anterior portion of the lip vermilion for the upper and lower lip, the position of the most protruded point of the lip vermilion, lip fissure inclination, and differences between the horizontal positions of the upper and lower lip vermilions. The dentoskeletal forms showed significant differences between classified lip vermilion profile patterns (P < .01).

CONCLUSIONS

(1) Vector quantization revealed that classifying lip vermilion profiles into seven representative patterns was optimal for maximizing differences in the configuration of the lip vermilion. (2) Lip vermilion profile shapes were found to be associated with horizontal lengths of the anterior cranial base, horizontal/vertical positions, inclination and length of the mandible, and horizontal positions and labio-lingual inclinations of the upper and lower incisors.