Canted occlusal plane ; etiology and evaluation part 1

etiology and evaluation of the canted occlusal plane are presented

1. Canted occlusal plane ;etiology and evaluation part 1 Dr Maher fouda Professor of orthodontics Mansoura Egypt

2. Turkish J Orthod Vol 27, No 4, 2015 Reference:

3. Frontal occlusal plane The frontal occlusal plane is represented by a line running from the tip of the right canine to the tip of the left canine. A transverse cant can be caused by the differential eruption of the maxillary anterior teeth or a skeletal asymmetry of the mandible .

4. The most important esthetic goal in orthodontics is to achieve a ‘‘balanced’’ smile, which can be best described as an appropriate positioning of the teeth and gingival scaffold within the dynamic display zone.

5. The display zone are affected by the size, shape, position, and color of the displayed teeth as well as the gingival contour, buccal corridor, and framing of the lips. Smile components

6. The Eight Components of a Balanced Smile ROY SABRI, DDS, MS ©2005 JCO, Inc . 1. Lip Line Upper Lip Length Lip Elevation Vertical Maxillary Height Crown Height Vertical Dental Height Incisor Inclination 2. Smile Arc Overintrusion of Maxillary Incisors Cant of the Occlusal Plane 3. Upper Lip Curvature 4. Lateral Negative Space

7. The Eight Components of a Balanced Smile ROY SABRI, DDS, MS ©2005 JCO, Inc. 5. Smile Symmetry 6. Frontal Occlusal Plane 7. Dental Components 8. Gingival Components

8. Cant of the Occlusal Plane: Extraoral forces, intermaxillary elastics, and orthognathic surgery can affect the cant of the occlusal plane. If the maxillary occlusal plane is canted upward anteriorly, for instance, the incisal edges will move away from the lower lip, resulting in a nonconsonant smile arc . Consonant (a) and non-consonant arc of the smile (b), determined by the upper incisal line and the internal surface of the lower lip

9. Cant of the Occlusal Plane: Conversely, if the occlusal plane has an excessive clockwise tilt, the upper incisal edges will be covered by the lower lip, making the smile arc less attractive

10. Retracted Close Up Teeth Apart . Note the Rise and Cant in the Incisal plane up to her right side.

11. Cant of the Occlusal Plane: Other factors that can affect the smile arc are attrition due to shortening of the central incisors, habits such as thumbsucking , excessive posterior vertical growth (mostly seen in brachyfacial patterns), and the lower lip musculature. Consonant and nonconsonant smiles: A , consonant smile with parallelism between the curvature of the maxillary incisal edge and the upper border of lower lip; B , nonconsonant smile, with no parallelism between the curves.

12. Intraoral frontal view depicting asymmetric open bite due to long persistent unilateral digit sucking habit.

13. Cant of the Occlusal Plane: Maxillary incisor inclination affects not only the lip line, but the smile arc as well, when the curvature of the incisal edges does not coincide with the border of the lower lip in smiling . Lip line with reduced incisor display due to proclined maxillary incisors.

14. Cant of the Occlusal Plane: Excessively proclined incisors will be associated with an everted lower lip, whereas uprighted or retroclined incisors will be partially covered by the lower lip.

15. Patient with canted occlusal frontal plane and unilateral posterior gingival smile.

16. The Eight Components of a Balanced Smile ROY SABRI, DDS, MS ©2005 JCO, Inc. 6. Frontal Occlusal Plane: Patient with canted occlusal frontal plane and unilateral posterior gingival smile. This relationship of the maxilla to the smile cannot be seen on intraoral images or study casts, and smile photographs can also be misleading.

17. The Eight Components of a Balanced Smile ROY SABRI, DDS, MS ©2005 JCO, Inc. 6. Frontal Occlusal Plane: Patient with canted occlusal frontal plane and unilateral posterior gingival smile. Therefore , clinical examination and digital video documentation are essential in making a differential diagnosis between smile asymmetry, a canted occlusal plane, and facial asymmetry . Smile asymmetry associated with smile limitation facial asymmetry to the left with a vertical component, canting the occlusal plane to the right

18. The Eight Components of a Balanced Smile ROY SABRI, DDS, MS ©2005 JCO, Inc. 6. Frontal Occlusal Plane Having the patient bite on a tongue blade or a mouth mirror in the premolar area during the clinical examination is a good way to recognize an asymmetrical cant of the maxillary frontal occlusal plane.

19. Smile design and mechanotherapy must take into account an esthetic plane of occlusion, which is often different from the natural plane of occlusion . A. Patient with asymmetrical cant of maxillary anterior transverse occlusal plane. B. Different bracket height on maxillary left canine vs. maxillary right canine. C. Patient after treatment. occlusal cant (OC) in the frontal plane .

20. esthetic plane of occlusion, The average point of contact between maxillary and mandibular first molars and the upper lip stomion is taken as a reference. Then a line is drawn between these two points to determine the FAOP

21. Occlusal Plane : The occlusal plane (OP) is an imaginary surface that is anatomically related to the cranium. Theoretically, it touches the incisal edges of the incisors and the tips of the occluding surfaces of the posterior teeth.

22. Therefore, the OP is the plane that would be established if a line were drawn through all the buccal cusp tips and incisal edges of the mandibular teeth and then broadened into a plane to include the lingual cusp tips, continuing across the arch to include the buccal and lingual cusp tips of the opposite side. The OP is not, in fact, a plane, but rather represents the mean curvature of this surface.

23. Because most jaw movements are complex, with the centers of rotation constantly shifting, a flat occlusal plane will not permit simultaneous functional contact in more than one area of the dental arch. The curvature of the occlusal plane is primarily a result of the fact that the teeth are positioned in the arches at varying degrees of inclination

24. The OP of the dental arches is curved in a manner that permits maximal utilization of the tooth contacts during chewing. This curvature of the dental arches has been referred to as the curve of Spee .

25. A second curve associated with the OP can be observed from a frontal view and is called the curve of Wilson.. Curve of Wilson: The natural curvature of the occlusal plane of the molar and premolar teeth in the coronal plane

26. In cephalometric radiographs (in the sagittal plane), the OP is defined as a line that joins the midpoint of the overlap of the mesiobuccal cusp of the first molar and the incisal edges of the incisors.

27. In posteroanterior (PA) radiographs (in the vertical plane), the OP is defined as a line that joins the buccal cusps of the right and left upper first molars in a transversal direction

28. The OP adapts to the alterations that occur with age, vertebral maturation, and changes in dental position.

29. Lateral cephalometric studies evaluating the OP in a sagittal direction indicated that the inclination of the OP alters according to changes in craniofacial structures during craniofacial growth and development.Schudy stated that condylar growth (as related to vertical growth) is the key to changes in the OP.

30. In the frontal plane, changes in the OP result from posterior rotation and relocation of the maxilla and mandible in a vertical direction. Illustrations of subjects in A, the ipsilateral group, with the frontal occlusal plane inclined toward the ipsilateral side of the mandibular deviation; and B, the contralateral group, with the frontal occlusal plane inclined toward the contralateral side of the mandibular deviation. Midline, CG-ANS; FOP, the line joining the bilateral maxillary first molars

31. The inclination of the OP increases in a clockwise direction during growth. Symmetric growth and development enables the conservation of the angles between the cranial planes and OP during an increase in vertical dimensions.

32. Although changes in the inclination of the OP in the sagittal plane are associated with growth and development .

33. C hanges in the inclination of the OP in the vertical plane result from asymmetric growth of the craniofacial structures and lead to an asymmetric OP; this is defined as OC. Canted maxillary anterior occlusal plane.

34. Occlusal Cant : Occlusal plane canting in the vertical plane is one of the parameters affecting smile esthetics and originates from facial asymmetry and/or vertical position asymmetry of the right and/or left quadrants of the dental arches without facial asymmetry. Facial asymmetry and hemimandibular hyperplasia   vertical position asymmetry of the right and/or left quadrants of the dental arches without facial asymmetry.

35. A 38-year-old woman sought orthodontic evaluation with concerns about missing teeth, an unesthetic anterior dentition, prominent lower incisors and protrusive lips. There was no contributing medical history, but she had a long history of limited, restorative dental care.

36. Extra-oral evaluation with the lips closed showed a symmetric bimaxillary protrusion with coincident dental and facial midlines. Upon smiling her dentition was unattractive due to an end-to-end incisal relationship, occlusal cant (more inferior on the right side), irregular spacing in the anterior segments, and intermaxillary midline diastemas .

37. Occlusal Cant : Occlusal cant is frequently associated with facial asymmetry; the reported frequency of facial asymmetry in cases involving this condition varies between 21% and 80%. Non-surgical Correction of Craniofacial Microsomia with Occlusal Plane Canting

38. This wide range may result from differences between reports in characteristics of facial deformity, types of skeletal malocclusion, age, or ethnicity.

39. In addition, observed differences in the proportion of facial asymmetry in OC may be due to variations in methods, symmetry criteria, or measurement sensitivity between studies. facial and intraoral photographs. A, Pretreatment; B, presurgery ; C, postsurgery

40. Good et al indicated that the incidence of asymmetry increases in patients with skeletal class III malocclusion and increased lower facial height. According to Severt and Proffit,OC is found in 41% of patients with class III malocclusion.

41. Symmetry and Asymmetry Perception: It has been demonstrated that symmetric faces are more attractive but not more so than less symmetric faces. Is a Symmetrical Face the Key to Attractiveness? 

42. Symmetry and Asymmetry Perception: However, preferences for symmetry cannot solely explain the attractiveness of average faces. Usually, symmetric faces are preferred by individuals; however, a person’s preference for symmetry was not correlated with their ability to detect it. Symmetry

43. Photo of smile modified to create occlusal canting of 2º Photo of smile with 0º occlusal canting . Photo of smile modified to create occlusal canting of 4º The perception of OC varies between lay persons, general dentists, and orthodontists. Oliveres et al concluded that an OC of 2 degrees was acceptable to lay persons, general dentists, and orthodontists.

44. Photo of smile modified to create occlusal canting of 2º Photo of smile with 0º occlusal canting . Photo of smile modified to create occlusal canting of 4º In addition, lay persons and general dentists found OC more acceptable than orthodontists. Lay persons failed to detect the existence of an OC reaching 3–4 degrees . Padwa et al concluded that 4 degrees is the threshold for detection of OC.

45. Etiologic Factors in Asymmetry and Occlusal Cant : Determination of asymmetries and classification of cases is complicated by the multifactorial nature of asymmetry. The etiology of asymmetry can be classified as consisting of hereditary and environmental factors.

46. The patient was a 19-year-old. Her chief complaint was anterior open bite and discrepancy of the midlines between the maxillary and mandibular arches. She was not aware of her facial asymmetry and was not dissatisfied with or concerned about it. There was no history of trauma to her head or jaw. The family history was not relevant, and the cause of her facial asymmetry was unknown . In the frontal view, the mandible was slightly deviated to the left, and the lip line was canted.

47. In the lateral view, the facial profile was straight, with upper and lower lip protrusion. The discrepancy between the maxillary and mandibular midlines was 4.0 mm, with the maxillary incisors inclined to the left and the mandibular incisors inclined to the right. Overbite and overjet were −2.0 and 4.0 mm, respectively. The occlusal plane was canted and almost parallel to the line passing through the left and right corners of the mouth. The anterior open bite extended from the left first premolar to the right first premolar. The molar relationships were Class III on the right and Class I on the left. There was no crossbite or scissorsbite in the posterior teeth, except in the right first premolar region  

48. Etiologic Factors in Asymmetry and Occlusal Cant: Cleft lip and palate,hemifacial microsomia , juvenile idiopathic arthritis, Treacher Collins syndrome, Albright syndrome, Apert syndrome, Crouzon syndrome, and craniosynostosis are the common hereditary factors that lead to facial asymmetry and OC. Treacher Collins Syndrome

49. Hemifacial microsomia  is a congenital condition in which the tissues on one side of the face are underdeveloped. It primarily affects the ear, mouth and jaw areas, though it may also involve the eye, cheek, neck and other parts of the skull, as well as nerves and soft tissue

50. The most important clinical findings in hemifacial microsomia are mandibular malformation with facial asymmetry and microtia . Hypoplasia of the soft tissues, orbital involvement, nerve disorders, and other affected anatomic structures are present with a wide range of variations Microtia  is a  congenital deformity  where the  pinna  (external ear) is underdeveloped

51. Her extraoral examiation revealed no significant facial asymmetry. The upper dental midline was coincident with the facial midline. There was an occlusal cant in the maxilla. Her profile view showed flat paranasal areas and slight midfacial retrusion with a straight facial profile Repaired Cleft lip and palate :

52. Mandibular condylar hypoplasia is facial deformity caused by a short mandibular ramus.  

53. (A) Patient with (juvenile idiopathic arthritis )JIA of the left temporomandibular joint. The lack of dentoalveolar development of the affected side results in dental compensations and an oblique occlusal plane. (B) Occlusion of the unaffected side and (C) of the affected side . Early Orthopedic Treatment and Mandibular Growth of Children with Temporomandibular Joint Abnormalities Seminars in Orthodontics, Vol 17, No 3 (September), 2011: pp 235-245

54. An Algorithm for Management of Dentofacial Deformity Resulting From Juvenile Idiopathic Arthritis: Results of a Multinational Consensus Conference Resnick et al. Management Algorithm for JIA Dentofacial Deformity. J Oral Maxillofac Surg 2019 The temporomandibular joints (TMJs) are affected in most patients with juvenile idiopathic arthritis (JIA), the most common chronic pediatric rheumatologic condition. In rare cases, TMJ arthritis may be the presenting or only feature of JIA. The TMJ is unique in that it contains the primary mandibular growth site just below a thin layer of fibrocartilage. As a result, synovitis caused by JIA may lead to both osseous degeneration and restriction of condylar growth

55. Environmental factors affecting facial asymmetry and OC include facial trauma and fractures (prenatal and postnatal), jaw cysts, and facial tumors as well as their surgical treatment, teratogens, hormonal disorders (such as gigantism or acromegaly), Romberg syndrome, posture . Acromegaly in an orthodontic patient American Journal of Orthodontics and Dentofacial Orthopedics Volume 130, Number 3

56. Environmental factors affecting facial asymmetry and OC include temporomandibular joint (TMJ) ankylosis , muscular disorders, abnormal mouth breathing, habits such as finger or lip sucking,

57. abnormal mouth breathing

58. Environmental factors affecting facial asymmetry and OC include long term bottle or pacifier use, pencil biting and nail biting, tooth extraction and carries, and incorrect use of force during orthodontic treatment or when using midline elastics. Upper incisors are canted descending from right to left due to pen chewing habit. Non-surgical orthodontic treatment of anterior open bite in an adult patient. White life design – Case presentation

59. Evaluation of Occlusal Cant Occlusal cant is related to the pattern of skeletal and/or dentoalveolar development and can be classified with or without facial asymmetry due to asymmetric development of the mandible, unilateral extruded molars, or asymmetric dentoalveolar development.

60. Results of finger sucking. Asymmetrical left side open bite and overjet unilateral extruded upper molars (C–E) asymmetric mandibular jaw growth;

61. Evaluation of Occlusal Cant: Patients with OC are evaluated by clinical assessment, frontal photographs, cephalometry , and 3-dimensional imaging methods

62. Evaluation of Occlusal Cant Pretreatment smile photographs Submental view photograph Occlusal plane canting

63. Evaluation of Occlusal Cant Pretreatment cephalogram Pre treatment OPG Pre Treatment PA cephalogram

64. Evaluation of Occlusal Cant Pre treatment volumetric CT scan

65. During clinical assessment, a tongue blade is placed across both first molars to evaluate the existence and degree of inclination of OC.

66. c) The occlusal plane is oblique in the same direction as the maxillary and mandibular planes

67. b) The positioning of the Fox plane plate on the superior arch shows the maxillary plane parallel to the bi-pupillary line with an interincisal midline shift to the left. The flat positioning of the plate on the inferior arch shows a significant cant of the mandibular plane. Fox plane plate

68. Evaluation of Occlusal Cant

69. 3D analysis with Treil . Evaluation of Occlusal Cant

70. Recently, the number of patients referred to orthodontic clinics as a result of TMJ disorders has been increasing. His chief complaints were clicking sounds in the TMJ and facial asymmetry with mandiubular deviation.

71. In patients with unilateral TMJ disorder, facial asymmetry is less associated with occlusal discrepancy; however, canting of the OP in these patients is increased because of mandibular hypoplasia on the affected side. Condylar hyperplasia Condylar hyperplasia (mandibular hyperplasia) is over-enlargement of the mandible bone in the skull

72. Differential Diagnosis and Treatment of Condylar Hyperplasia JCO/JANUARY 2019 The patient had experienced a fall from stairs when he was 7 years old , but reported no visible injury or treatment at that time Tc scan indication of a hyperactive condyle on the left side.

73. This young adult patient presented with recent onset right mandibular growth and change in occlusion. A technetium scan revealed right condylar hyperplasia resulting in progressive facial asymmetry.

74. Detailed clinical examination and radiological evaluation of the TMJ are essential in such patients with TMJ disorders OPENING AND CLOSING OF MOUTH Teeth normally close symmetrically, the jaw is normally centered ALIGNMENT OF TEETH Note cross bite, under or over bit

75. RANGE OF MOTION measure from top tooth edge to bottom tooth edge .Opening and closing of mouth Normal opening ~ 40-50 mm Functional opening or necessary for most dental procedures ~ 36 mm or at least 2 knuckles between teeth The knuckles are the  joints  of the  fingers

76. SYMMETRY OF FACIAL STRUCTURES Eyes, nose, mouth, length of mandible POSTURE Forward head posture, rounded shoulders and scapular protraction is common

77. BREATHING PATTERN mouth breathing, short upper lip

78. TONGUE OR LIP FRENULUM RESTRICTION

79. LISTENING FOR JOINT NOISES, CLICKS, POPS OR CREPITUS

80. PROTRUSION OF MANDIBLE Normal ~ 10 mm • Lateral deviation of mandible Normal ~ 10 mm • Note asymmetrical movements, snapping, clicking, popping or jumps

81. RECORD DEVIATIONS Lateral movements with return to midline. The opening pathway is altered but returns to midline, usually indicative of a disc displacement WITH reduction or could be neuromuscular dysfunction

82. RECORD DEFLECTIONS Lateral movements without return to midline.  Deflections are usually associated with Disc Dislocations without reduction or a unilateral muscle restriction.

83. CRANIAL LOADING OF MANDIBLE PROVIDES ADDITIONAL VALUABLE INFORMATION PROM: apply overpressure at the end range of AROM to assess end feel

84. STRENGTH Assess muscles of mastication, deep cervical flexors and scapular stabilizers

85. Temporomandibular joint imaging: current clinical applications, biochemical comparison with the intervertebral disc and knee meniscus, and opportunities for advancement Skeletal Radiol (2020) 49:1183–1193 16-year-old female with normal TMJ. Sagittal (a) and coronal (b) non-contrast CT images in bone windows demonstrate a normal temporomandibular joint. Note the normal joint space. A, articular tubercle; B, mandibular (or glenoid) fossa; C, external auditory canal; D, mandibular condyle

86. Temporomandibular joint imaging: current clinical applications, biochemical comparison with the intervertebral disc and knee meniscus, and opportunities for advancement Skeletal Radiol (2020) 49:1183–1193 30-year-old female with normal TMJ. Sagittal proton densityweighted non-contrast MR images demonstrate a normal temporomandibular joint with normal positioning of the anterior and posterior bands of the articular disc (white arrows) and normal positioning of the mandibular condyle (black arrows) in the close-mouth (a) and open-mouth (b) positions

87. Panoramic TMJ radiographs consisting of the combination of the frontal and lateral projections for each TMJ at the maximally open jaw position. TMJ: temporomandibular joint. LatTMJ : panoramic projection, lateral view of the TMJ. FrnTMJ : panoramic projection, frontal view of the TMJ. Diagnostic accuracy and reliability of panoramic temporomandibular joint (TMJ) radiography to detect bony lesions in patients with TMJ osteoarthritis

88. Example of the four types of radiographic images in a patient with TMJ osteoarthritis . Erosion and osteophyte lesions are noted on the articular surface of the mandibular condyle. PanRad : panoramic radiography. LatTMJ : panoramic projection, lateral view of the TMJ. FrnTMJ : panoramic projection, frontal view of the TMJ. CBCT: cone-beam computed tomography. 3D: three-dimensional reconstruction.

89. Posteroanterior radiography is also necessary in the evaluation and objective measurement of OC. Analysis of PA radiographs allows easy visual comparison of asymmetry.

90. The most commonly used asymmetry analyses are Grummons frontal analysis and Sassouni analysis. These analyses demonstrate the parallelism and asymmetry of facial points and planes according to predetermined planes.

91. The horizontal distance from the menton to the midsagittal plane on PA radiographs is measured as deviation. The angle of the OP to the true horizontal plane is measured as the angle of OC.

92. The angle of the OP to the true horizontal plane is measured as the angle of OC.

93. It has been demonstrated that the degree of OC relative to the true horizontal plane as measured cephalometrically in the frontal plane is equal to the linear millimeter difference between the right and left medial canthus and the right and left canine tips.

94. . Measurement of occlusal cant in the maxilla. A, The magnitude of occlusal cant by measuring the degree of canting relative to the true horizontal. The reference lines for determining the cant are as follows: a true horizontal represented by a tangent to the normal supraorbital rims (1) and a vertical line drawn through the crista galli and upper third of the nasal septum (2). The degree of cant is determined with respect to the true horizontal. On this AP cephalogram , the degree of canting of the occlusal plane was 6 degrees. B, The magnitude of occlusal cant can be measured by evaluating the medial canthus-canine distance. In the patient above, the medial canthus to right canine distance was 62 mm; the distance to the left canine was 56 mm, for a total vertical discrepancy of 6 mm.

95. However, the effectiveness of PA radiographs may be reduced by head rotation or improper landmark identification.

96. In the presence of asymmetry, basilar/ submentovertex (SMV) radiographs are also useful. (a-b) Anatomic landmarks and reference planes used in submentovertex cephalometric analysis (Tracing 1). TPA, transporionic axis: line passing through the left and right tip of ear rods corresponding to the line passing through the midpoint of external auditory meatus (LM, left Mei; RM, right Mei); MP, midsagittal axis: perpendicular bisecting TPA; RCoL , right condylion lateralis : most lateral aspect of right condyle; RCoM , condylion medialis : most medial aspect of right condyle; LCoL , left condylion lateralis : most lateral aspect of left condyle; LCoM , left condylion medialis : most medial aspect of left condyle; RCoL -MP, right condylion lateralis -midline: distance from right L-point to MP; RCoM -MP: right condylion medialis -midline: distance from right M-point to MP; LCoL -MP, left condylion lateralis -midline: distance from left L-point to MP; LCoM -MP, left condylion medialis -midline: distance from left M-point to MP

97. The SMV radiographs can be used to diagnose dental arch deviations resulting from midline shifts, craniofacial asymmetry, condylar position in functional mandibular deviation, mandible asymmetry, and, in particular, maxillary asymmetry in cleft lip and palate patients.

98. The SMV radiographs allow the assessment of asymmetry within each component part of the craniofacial complex as well as the relative relationship of these parts to one another. In addition, SMV radiographs are less vulnerable to head rotation .

99. Orthopantomograms provide information about mandibular asymmetry. Habets et al described condylar height symmetry calculated by condylar and ramus heights on orthopantomograms . Measurement on the orthopantomogram (OPG), according to Habets et al. O1 and O2, most lateral points of the ramus; A, ramus tangent; B, perpendicular line from A to the most superior part of the condylar image; C, corpus tangent; CH, condylar height; and RH, ramus height.

100. Three-dimensional computed tomography (CT) can provide information for use in diagnosis and treatment planning. Landmarks and reference planes used in this study. A and D. Frontal view; B and E. Lateral view; C and F. View from below. D and E. Show the ramal inclination in the frontal and lateral directions to FH plane (ARI, anteroposterior ramal inclination; MRI, mediolateral ramal inclination). Please see Table 1 for abbreviations of the landmarks .

101. Because of the complex three dimensional nature of facial asymmetry, CT scans have become routine in the evaluation of asymmetry cases that cannot be assessed using conventional methods. Reconstructed CT scan of face showing (a) Facial asymmetry, protruding upper central incisors. (b) Bony synostosis between the right zygomatic arch of maxilla and the ramus of the mandible. (c) Normal temporomandibular joint on right side is seen .

102.  computerized tomography scan (CT or CAT scan) uses computers and rotating X-ray machines to create cross-sectional images of the body. These images provide more detailed information than normal X-ray images. They can show the soft tissues, blood vessels, and bones in various parts of the body.

103. C one-beam computed tomography systems (CBCT) are a variation of traditional computed tomography (CT) systems. The CBCT systems used by dental professionals rotate around the patient, capturing data using a cone-shaped X-ray beam

104. Magnetic resonance imaging (MRI) is a  medical imaging  technique used in  radiology  to form pictures of the  anatomy  and the  physiological  processes of the body.  MRI scanners  use strong  magnetic fields , magnetic field gradients, and  radio waves  to generate images of the organs in the body. MRI does not involve  X-rays  or the use of  ionizing radiation , which distinguishes it from  CT  and  PET scans . MRI is a  medical application  of  nuclear magnetic resonance  (NMR) which can also be used for imaging in other  NMR applications , such as  NMR spectroscopy

105. The evaluation of frontal facial photographs is a diagnostic tool used to evaluate soft-tissue asymmetry and lip cants.

106. It was concluded that an OP angle of 2.15–2.90 degrees on a digital photograph is acceptable. 27-year-old patient with active condylar hyperplasia on the right side, inclination of the occlusal plane in both maxilla and mandible ( AeC ) patient exhibits the OP with a 2.5 degrees transverse cant, having the interpupillary line as the reference plane

107. The incidence of a cant greater than 1 degree between the bilateral mouth corners was found to be 28.6% when the face was measured on standardized frontal facial photographs . - Relationship established between occlusal plane and maxillary and mandibular inferior borders.