decompensation of skeletal malocclusion.pptx

This seminar provides a comprehensive understanding of decompensation in skeletal malocclusions, emphasizing its pivotal role in presurgical orthodontics for orthognathic surgery. Starting with Salzmann’s skeletal classification, the session explains Class I, II, and III skeletal patterns and their respective dentoalveolar compensations. These include incisor retroclination or proclination, occlusal curve changes, and transverse arch width discrepancies.

The seminar outlines the importance of reversing natural compensations—termed presurgical orthodontic decompensation—to align teeth with their basal bones, thus enabling precise surgical repositioning. It details decompensation protocols in all three planes: sagittal (using elastics and bracket adjustments), vertical (leveling the curve of Spee), and transverse (correcting crossbites with appliances or SARPE).

Attendees will gain insight into diagnostic tools such as lateral cephalograms and the critical role of CBCT in 3D planning. Extraction strategies tailored to malocclusion class and clinical limitations of decompensation are also discussed. This seminar is essential for orthodontic postgraduates and clinicians involved in surgical case planning and interdisciplinary management of complex malocclusions

1. DECOMPENSATION OF SKELETAL MALOCCLUSION Presented by DR ARUSHI MALHOTRA MDS 1 st YEAR

2. CONTENTS PART A Introduction Salzmann's Skeletal Classification (1950) Types: Skeletal Class I, II, III Skeletal Classifications Class I Class II Class III Compensation Sagittal, Vertical, and Transverse Jaw Relationship Adjustments Presurgical Orthodontics Alignment, Leveling , and Decompensation Decompensation Class II, III, Vertical Dysplasia Need for Presurgical Decompensation :. Decompensation in Different Planes Sagittal Plane Vertical Plane Transverse Plane Extraction pattern in different malocclusions Limits of Decompensation Diagnostic Tools CBCT Role: 3D Analysis for Decompensation Planning PART B Complications Inadequate Decompensation : Sagittal, Vertical, and Transverse Planes Clinical examples, surgical solutions References

3. INTRODUCTION Salzmann in 1950 was the first to classify the underlying skeletal structure Skeletal pattern can also be classified using measurements obtained from lateral skull radiographs. In this case the assessment is made using the angle ANB . An ANB angle of 2 to 4°denote a skeletal class I pattern, greater than 4° is class II, and less than 1° is class III .

4. SKELETAL CLASSIFICATION According to SALZMANN Skeletal class I Skeletal class II Skeletal class III

5. SKELETAL CLASS I These malocclusion were purely dental with the bones of the face & jaws being in harmony with one another & with the rest of the head. The profile is orthognathic ( Straight ) REFERENCE- BHOJIA DENTAL COLLEGE AND HOSPITAL, DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPAEDICS

6. SKELETAL CLASS II These include malocclusion with a subnormal distal mandibular development in relation to the maxilla. The profile is prognathic (Convex) REFERENCE- BHOJIA DENTAL COLLEGE AND HOSPITAL, DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPAEDICS

7. SKELETAL CLASS III Here there is an overgrowth of the mandible with an obtuse angle. Profile is retrognathic profile (Concave ). REFERENCE- BHOJIA DENTAL COLLEGE AND HOSPITAL, DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPAEDICS

8. COMPENSATION

9. COMPENSATION SKELETAL CLASS II To Compensate Larger Discrepancies (increased overjet ) Upper Incisors are retroclined and lower incisors are proclined to maintain normal overjet . Akiko Abe, Sachio Tamaoki , Masao Ozaki & Hiroyuki Ishikawa (2012) Analysis of dental compensation in cases using three-dimensional measurement of gnathostatics models, Orthodontic Waves, 71:1, 41,

10. COMPENSATION FOR VARIATION IN THE SAGITTAL JAW RELATIONSHIP SKELETAL CLASS III Upper Incisors are proclined and the lower incissors are retroclined to maintain the normal overjet . Akiko Abe, Sachio Tamaoki , Masao Ozaki & Hiroyuki Ishikawa (2012) Analysis of dental compensation in cases using three-dimensional measurement of gnathostatics models, Orthodontic Waves, 71:1, 41,

11. COMPENSATION FOR VARIATION IN THE VERTICAL JAW RELATIONSHIP SKELETAL OPEN BITE Posterior dentoalveolar segment intrudes, The anterior dentoalveolar segment extrudes or both can happen, to maintain the normal overbite SKELETAL DEEP BITE Posterior dento alveolar segment can extrude or the anteriors can intrude to maintain a normal overbite . Akiko Abe, Sachio Tamaoki , Masao Ozaki & Hiroyuki Ishikawa (2012) Analysis of dental compensation in cases using three-dimensional measurement of gnathostatics models, Orthodontic Waves, 71:1, 41, REFERENCE- BHOJIA DENTAL COLLEGE AND HOSPITAL, DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPAEDICS

12. COMPENSATION FOR VARIATION IN THE TRANSVERSE JAW RELATIONSHIP Discrepancy between narrow maxillary base and a wide mandibular base is Compensated by buccal tilting of upper teeth and lingual tilting of the lower teeth. Discrepancy between wide maxillary base and a narrow mandibular base is Compensated by lingual tilting of upper teeth and buccal tilting of the lower teeth . Akiko Abe, Sachio Tamaoki , Masao Ozaki & Hiroyuki Ishikawa (2012) Analysis of dental compensation in cases using three-dimensional measurement of gnathostatics models, Orthodontic Waves, 71:1, 41,

13. PRESURGICAL ORTHODONTICS Alignment and leveling Decompensation. Arch coordination

14. ORTHODONTIC APPLIANCE Use metal bracket is the best. Use 0.022 slot to allow use rigid wire for more stability. Second molar should be banded.

15. ALIGNMENT & LEVELING Dental crowding, spacing, and rotations should be corrected before orthognathic surgery . If segmental osteotomy is planned we should provide spaces between the roots, so we can tip the bracket. Curve of spee should be flat (according to ideal occlusion). Extraction should be avoided if the space of the jaw permits favorable dental alignment. . REFERENCE- BHOJIA DENTAL COLLEGE AND HOSPITAL, DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL ORTHOPAEDICS

16. ALIGNMENT & LEVELING In short face , when an increase in face height is desired , lower incisors should not be depressed before surgery . Maintenance of curve of spee is needed. In normal or excessive face height, levelling by intruding the incisors should be done before surgery .

17. DECOMPENSATION Most severe skeletal jaw discrepancies are partly compensated. This natural phenomena called “ dentoalveolar compensation”, I n preparation for orthognathic surgery, it is necessary to remove any dental compensations present and to place the teeth in a favorable position with their supporting bone. This is called P resurgical decompensation . Presurgical orthodontic decompensation is essential to enable the surgeon to make a considerable amount of surgical correction. Decompensation makes the maxillomandibular dental relation temporarily worse. Hence, it is sometimes called R everse orthodontics

18. DECOMPENSATION

19. Types of Malocclusions Requiring Decompensation Class II Malocclusion: Mandibular retrusion ; proclined lower incisors. Class III Malocclusion: Mandibular protrusion; retroclined lower incisors. Vertical Dysplasia: Open bites or deep bites needing vertical correction.

20. NEED FOR PRESURGICAL DECOMPENSATION 1 . To position the teeth in an ideal axial inclination with respect to the jaws. 2. To optimize the magnitude of surgical advancement or repositioning. 3. For better esthetics , stability and function. 4. If malpositioned anterior teeth are not corrected , they may hinder the repositioning of jaws at the time of surgery.

21. DECOMPENSATION IN DIFFERENT MALOCCLUSION DECOMPENSATION IN CLASS II . • Use class III elastic to upright lower incisor Decompensation in class III • Use class II elastic to procline lower incisors

22. DECOMPENSATION IN DEEP BITE In patients with deep bite, there is nearly always an excessive curve of Spee in the lower arch and occasionally a reverse curve in the upper arch. In these cases, the curve of Spee is leveled intruding the incisors or extruding the posterior teeth .

23. DECOMPENSATION IN OPEN BITE

24. PRESURGICAL ORTHODONTICS OBJECTIVES IN THE TRANSVERSE PLANE The problem is the skeletal or dental Dental discrepancies are usually treated by means of buccal tipping of the posterior teeth while skeletal discrepancies are corrected by bodily movement of the posterior teeth. T he tipping should not exceed 4 to 6 mm total. Bodily movement of the posterior teeth should be done by means of segmental osteotomy.

25. Absolute skeletal transverse discrepancy requires planning for segmental osteotomy or surgically assisted rapid palatal expansion (SARPE). SARPE technique is used in cases with a severe discrepancy or when the transverse defect of the maxillary bone is an isolated skeletal anomaly. Segmental maxillary osteotomy is used for more modest defects (up to 7 mm).

26. IS THE PROBLEM RELATIVE OR ABSOLUTE Articulation of the casts into a class I occlusion allows the clinician to easily distinguish between relative and absolute maxillary constriction. If the occlusion is proper when the casts are brought into class I canine relationship the discrepancy is relative; otherwise, if a crossbite still exists, then the discrepancy is absolute.

27. OBJECTIVES OF PRESURGICAL ORTHODONTICS FOR CLASS II MALOCCLUSION Aspect Class II Malocclusion Natural Compensation - Retroclination of upper incisors - Proclination of lower incisors Orthodontic Decompensation - Proclining retroclined upper incisors - Uprighting proclined lower incisors - Increases overjet Surgical Benefit - Maximum mandibular advancement - Establishes Class I canine relationship Eztraction pattern - Extraction of upper second premolars (prevents further retroclination of upper incisors) - Extraction of lower first premolars (facilitates uprighting of lower incisors) Extraction Space Closure - Required before surgery

28. Extraction Plan in class II Decompensation

29. OBJECTIVES OF PRESURGICAL ORTHODONTICS FOR CLASS III MALOCCLUSION Aspect Class III Malocclusion Natural Compensation - Proclination of upper incisors - Retroclination of lower incisors Orthodontic Decompensation - Uprighting proclined upper incisors - Proclining retroclined lower incisors - Increases reverse overjet Surgical Benefit - Maximum mandibular setback Extraction pattern - Extraction of upper first premolars (facilitates uprighting of upper incisors) - Extraction of lower second premolars (prevents further retroclination of lower incisors) Extraction Space Closure - Required before surgery

30. Extraction pattern in class III D ecompensation

31. LIMITS OF DECOMPENSATION IN DIFFERENT MALOCCLUSIONS

32. CLASS II VS CLASS III MALOCCLUSION

33. DIAGNOSTIC TOOLS FOR DECOMPENSATION

34. KEY USES IN DECOMPENSATION Sagittal Plane Adjustments : Visualizes incisor proclination or retroclination caused by natural compensations in Class II and Class III malocclusions. Determines the extent of decompensation needed to align incisors with their skeletal bases.

35. Transverse Discrepancies : Detects and measures crossbites or arch width discrepancies. Guides the expansion or realignment needed before surgery. Vertical Plane Issues : Identifies open bites or deep bites exacerbated by dental compensations. Assists in determining the need for segmental osteotomies or other vertical corrections

36. ROLE OF CBCT IN DECOMPENSATION PLANNING Advantages of CBCT - Provides 3D imaging of roots, bone, and surrounding structures. - Accurate measurements for surgical planning. - Identifies bone limitations for incisor movement. Clinical Example - A Class III patient with mandibular incisor retroclination planned using CBCT achieved optimal decompensation .

37. REFERNCES Contemporary Orthodontic 6th edition – William R. Proffit . Khechoyan DY. Orthognathic surgery: general considerations. In Seminars in plastic surgery 2013 Aug (Vol. 27, No. 03, pp. 133-136). Thieme Medical Publishers . Posnick J. Craniofacial and Maxillofacial Surgery in Children and Young Adult. Saunders; 2000 Akiko Abe, Sachio Tamaoki , Masao Ozaki & Hiroyuki Ishikawa (2012) Analysis of dental compensation in cases using three-dimensional measurement of gnathostatics models, Orthodontic Waves, 71:1, 41 , Principles Of Oral And Maxillofacial Surgery- Peterson Orthodontic Preparation for Orthognathic Surgery Abdolreza Jamilian , Alireza Darnahal and Letizia Perillo , 2015

38. THANK YOU