Classification of Dental Malocclusion

Classification of dental malocclusion and related studies.

1. Classification of Malocclusion By- Isaac (4 Yr)

2. Contents Andrew’s Six Keys of Occlusion Skeletal Classification British Standard Classification Canine Classification Simon’s Classification Ackerman and Proffit’s Classification Five Characteristics Classification

3. The concepts, which are described here are based on Lawrence F Andrew’s works on 120 non-orthodontic models based upon which he gave six keys to normal occlusion and developed the “straight wire appliance.” Andrew’s Six Keys of Occlusion

4. Key 1: Molar Relationship ( Interarch Relationship) The mesiolingual cusp of the maxillary first permanent molar seats in the central fossa of the mandibular first permanent molar. The distal surface of the distobuccal cusp of the maxillary first permanent molar contacts or occludes with the mesial surface of the mesiobuccal cusp of the mandibular second permanent molar.

5. Key 2: Crown Angulations In the normal occluded teeth, the gingival portion of the long axis of each crown is distal to the occlusion portion of that axis . The degree of the angulation varies with each tooth type.

6. Key 3: Crown Inclination • The angle between a line is 90º to the occlusal plane, as w ell as a line tangent to the middle of the labia or the buccal surfac e of clinical crown, which is referred to as crown inclination 1. Anterior Crown of Central and Lateral Incisors : In the maxillary and mandibular incisors, the incisal portion of the labial surface of the crown of the anterior teeth is labial to the gingival portion. In all the other crowns , the occlusal portion of the labial or buccal surface is lingual to the gingival portion. 2. Maxillary Posterior Crowns : As compared to the cuspids and bicuspids, lingual crown inclination is slightly more pronounced in the molars. In the maxillary arch, lingual/palatal inclination progressively increases from cuspids/canines to molars that is to say that the occlusal table of individual posterior teeth tilts progressively towards the palate as we move posteriorly.

7. 3. Mandibular Posterior Crowns : There is a progressive increase in the lingual inclination.In the mandibular arch, lingual inclination progressively increases from cuspids/canines to molars that is to say the occlusal table of individual posterior teeth tilts progressively towards the tongue as we move posteriorly.

8. Key 4 : Absence of Rotation • In order to achieve correct occlusion, none of the teeth should be rotated, rotated molars and premolars occupy more space in the dental arch than normal. • Rotated canines adversely affect esthetics and may lead to occlusal interference. • Rotated incisors may occupy less space than those correctly aligned.

9. Key 5 : Presence of Tight Contacts There should be tight contacts and absence of any spacing . Tight contacts are an essential part to maintain the integrity of any arch form, especially the dental arches.

10. Key 6 : Flat occlusal plane The curve of Spee should be relatively slight or flat. The vertical distance between any tooth and a line joining the most prominent cusp tip of the mandibular molar and central incisor (curve of Spee ) should not exceed1.5 mm . A normal occlusion has a flat occlusal plane.

11. Skeletal Classification Skeletal malocclusion can be caused by defects in size,position or relationship between the upper and lower jaws.The skeletal malocclusions can occur in sagittal, verticaland transverse planes .

12. • Class 1 : Maxilla and mandible are in harmony with each other . •Class 2 : Maxilla lies ahead of mandible with reference to anterior cranial base. In other words, maxilla is prognathed . • Class 3 : Maxilla lies posterior to mandible with reference to anterior cranial base. In other words, maxilla is retrognathed .

13. British Standard Classification Of Incisor Relationship (1983) Based upon the incisor relationship proposed in 1983, molar relationship is not considered in some cases.

14. • Class 1: lower incisal edges occlude with or lie immediately below the cingulum plateau of the upper incisors . •Class 2: lower incisal edge lies posterior to the cingulum plateau of the upper incisors. Class II Division 1 Incisor Relationship : The upper central incisors are proclined or of average inclination. There is an increase in overjet . Class II Division 2 Incisor Relationship : The upper central incisors are retroclined . The overjet is usually minimal but may be increased. • Class 3: lower incisal edges lies anterior to the cingulum plateau of the upper incisor .

15. Canine Relationship Canine relationships are classified into following three classes.

16. Class I Canine Relationship : mesial inclination of the cusp of the upper canine , which overlaps the distal incline of the cusp of lower canine . Class II Canine Relationship : distal incline of the cusp of upper canine, which overlaps the mesial incline of the cusp of lower canine are termed as class II canine relationship . Class III Canine Relationship : l ower canine is forwardly placed as compared to upper canine . Hence, there is no relationship between upper and lower canine that exist and is referred as class III canine relationship.

17. Simon’s Classification Simon’s classification is based on anteriorposterior ,transverse and vertical plane relationships of the dental arches . Simon’s system of classification made use of three anthropometric , which are 1. Frankfort horizontal plane 2. Orbital plane 3 . Midsagittal plane Simon’s classification of malocclusion is based on abnormal relationship of the dental arches from their normal position in relation to anteroposterior, transverse and vertical planes.

18. 1. Frankfort Horizontal Plane (FH Plane) - This plane is from upper margin of external auditory m eatus to the infraorbital margin. This plane describes the vertical relationship of the dental arches . Attraction : If a dental arch or part of it is closure than normal to the Frankfort plane, then it is called as attraction. Abstraction : If a dental arch or part of it is farther away from Frankfort plane, then it is called as abstraction.

19. 2. Orbital Plane - Orbital plane is perpendicular to the FH plane, dropped down from infraorbital margin of the bony orbit . Simon law of canine: According to Simon, orbital plane should pass through the distal third of the maxillary canine and is called as Simon’s law of cuspid. Protraction : If dental arches or part of it is farther from orbital plane then it is called as protraction. Retraction : If dental arches or part of it is closure to orbital plane, then it is referred as retraction.

20. 3.Midsaggital Plane- Midsagittal plane is used to describe the transverse relationship of the dental arches . C ontraction : If dental arch or part of it is closure to the midsagittal plane, it is referred as contraction. D istraction : If dental arch or part of it is farther away from the midsagittal plane, then it is called as distraction.

21. ACKERMAN-PROFIT SYSTEM OF CLASSIFICATION Ackerman andProfit gave an all-inclusive method of diagramming and c ategorizing malocclusions to overcome the limitations of the Angle’s classification system in which five characteristics and their interrelationships are assessed using a modified Venn diagram. Five characteristics assessed are: 1. Alignment 2. Profile 3 . Type 4. Class 5. Bite depth In this classification a set theory is used where sets or groups represent malocclusions. A group contained within a larger enveloping group is a subset of the latter(enveloping group). A subset has the characteristics of its outer group also along with its own characteristics.

22. GROUPS AND SETS GROUP 1: is the outer all enveloping group/universe, which represents alignment of teeth, since the degree of alignment and symmetry are common to all directions. GROUP 2 : representing the facial profile, becomes a major set within the universe (group 1), as the profile is affected by many malocclusions . GROUP 3,4 & 5 : represent deviations in three planes of space that is transverse (lateral), sagittal (anteroposterior)and vertical plane, respectively. GROUP 6,7 & 8 : The overlapping groups 6, 7 and 8 at the center of theVenn diagram represent more severe problems, with characteristics from their enveloping groups. Group 9 : The group 9 at the exact center would be the most severe, with involvement of criteria from all the groups that is alignment , profile, transverse, anteroposterior and vertical problems .

23. ADDITION TO THE FIVE CHARACTERISTICS CLASSIFICATION SYSTEM • Two things particularly help this more thorough analysis: Esthetic line of occlusion. Rotational axes. 1 . ESTHETIC LINE OF OCCLUSION : Esthetic line of occlusion, follows the facial edges of the maxillary anterior and posterior teeth.

24. 2 . ROTATIONAL AX E S : • In addition to relationship in the transverse, antero-posterior and vertical planes of space used intraditional 3-D analysis, rotations around axes perpendicular to three planes also must be evaluated. • It's a useful way to evaluate the relationship of the teeth to the soft tissues that frame their display. Pitch. Roll. Yaw.

25. PITCH- •The vertical relationship of the teeth to the lips & cheeks can be conventionally described as up- down deviations a round the antero-posterior axes. •Evaluated clinically & from cephalometric radiographs . ROLL- •Roll describes the vertical position of the teeth when this is different on the right & left sides. •Viewed as up-down deviations around the transverse axes. •It's seen with lips relaxed and more clearly on smile, in both frontal and oblique views. YAW- •Rotation of the jaw or dentition to one side or the other, around vertical axes, produces a skeletal or dental midline discrepancy. •Viewed as left-right deviations around the vertical axes.

26. Advantages of Ackerman-Profit Classification : The complexities of malocclusion are explained . All three planes or dimensional problems are included . Profile of the patient is given due consideration . This classification helps in complete diagnosis and differential treatment planning. Differentiation between skeletal and dental problem is made easily with this system of classifying malocclusions Arch length problems are evaluated. Ackerman: Profit introduced a new method of classification to overcome the drawbacks of traditionalAngle’s classifications . Readily adaptable to the computer processing. Disadvantages of Ackerman-Profit Classification : Etiological considerations are not included in the classification . This system of classifying malocclusion is based only on static occlusion. Functional occlusion not included.

27. REFERENCE •ORTHODONTICS PRINCIPLES AND PRACTICE, PHULARI (2” EDITION) • CONTEMPORARY ORTHODONTICS, WILLIAM R.PROFFIT (5". EDITION) • INTRODUCTION TO ORTHODONTICS, LAURAMITCHELL (30. EDITION) • ORTHODONTICS, PREM KUMAR (2". EDITION)

28. END OF DISCUSSION, ANY QUESTIONS ? .