Management of Canted Occlusal plane in Orthodontics.pptx

management of canted occlusal plane and assymetric smile in orthodontics

1. Presented by: Safa Basiouny MSc, PhD Orthodontics Lecturer of Orthodontics , Faculty of Dentistry, Tanta University Occlusal Plane Canting

2. 01 02 03 04 05 Definitions Incidence Etiology Classification and Diagnosis Treatment 06 Biomechanical consideration

3. In cephalometric radiograph (in sagittal plane): Anatomical Occlusal plane: A line passing through one half of the cusp heights of the first permanent molars and one half of the overbite of the incisors. " Enlow " Or the line bisecting the overlapping cusps of the first molars and incisor overbite. "Down“ Esthetic plane of occlusion: The upper incisor lies commonly 3mm below a relaxed upper lip. So a line joining this point and distobuccal cusp tip of the upper first molar represents the esthetic occlusal plane Functional occlusal plane: A horizontal line from the posterior most occlusal contact of the last fully erupted mandibular molars extending anteriorly to the anterior most occlusal contact of the fully erupted premolars. " Enlow " Or the line which represents the functional table of occlusion in the first permanent molar, second pre molar and first pre molars areas. "Harvold"

4. In posteroanterior (PA) radiographs (in the transverse 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. Occlusal cant (OC): The rotation of the object in its longitudinal plane. 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.

5. Incidence of OP canting According to Severt and Proffit , 41% of Class III malocclusion cases have OC Occlusal cant is frequently associated with facial asymmetry; the reported frequency of facial asymmetry in cases have OC varies between 21% and 80% .

6. 1 2 Hereditary factors Environmental factors Etiologic Factors in Asymmetry and Occlusal Cant Cleft lip and palate Hemifacial microsomia syndromes like Treacher Collins syndrome •Facial trauma and fractures •Jaw cysts, and facial tumors as well as their surgical treatment •Romberg syndrome posture •Unilateral temporomandibular joint disorder e.g hyperplasia, ankylosis 3 4 5 Unilateral habits Habits such as finger or lip sucking, pencil and nail biting Asymmetric smile Iatrogenic tooth extraction and incorrect orthodontic mechanics

7. Classification of OP canting 01 With facial asymmetry 01 Type 1 02 Type 2 02 Without facial asymmetry Has a wavy occlusal plane, but clinically, the crowns are in good angulation and inclination Has total maxillary skeletal canting

8. Perception of OP canting Oliveres et al., concluded that an OC of 2⁰ was acceptable to lay persons, general dentists, and orthodontists. In addition, lay persons and general dentists found OC more acceptable than orthodontists. Lay persons failed to detect the existence of an OC reaching 3–4⁰. Padwa et al concluded that 4⁰ is the threshold for detection of OC. An increase in both occlusal plane cant and gingival display negatively influences smile attractiveness, but it is interesting that the occlusal plane cant has less influence when gingival display increases, and vice versa

9. Gummy smile OC Perception of OP canting

10. Gummy smile OC Perception of OP canting

11. Photographs Software Devices Radiographs Midline Diagnosis of Occlusal Cant

12. Photographs Photographs Software Devices Radiographs Midline Two photographs are important in diagnosis of OC: photograph of a spontaneous smile must be captured to show the maximum elevation of the upper lip. another photograph with a spontaneous smile and the mouth slightly opened , to evaluate the lower arch and the parallelism of the curvature of the upper arch with the lower lip

13. Photographs Software Devices Radiographs Midline by the use of reference lines as:   Bipupilar line may be transferred from the original position to the commissures region , to the gingival contour or tip of the cusp of one canine , or even the incisal edge of one incisor 2. Other lines may be drawn following the contour of the upper arch, lower arch, lower lip or the labial architecture, to compare the symmetry among them.

14. Photographs Software Devices Radiographs Midline Wooden tongue depressor or a metallic ruler can be used in the posterior region, with the patient in occlusion, allowing the analysis of the asymmetries in this region with greater precision Digital calipar

15. Radiographs Radiographs Photographs Radiographs Software Devices Radiographs Midline PA teleradiography Must be used especially when severe skeletal asymmetries are present, and the treatment plan requires an orthognathic surgery as the main step to correct the canted occlusal plane Lateral cephalometric Angle of occlusal cant (OC): The angle of the OP to the true horizontal plane is measured as the angle of OC. Mean value is 9.3⁰

16. Radiographs Radiographs Photographs Radiographs Software Devices Radiographs Lateral cephalometric Angle of occlusal cant (OC): The angle of the OP to the true horizontal plane is measured as the angle of OC. Mean value is 9.3⁰ PA teleradiography Must be used especially when severe skeletal asymmetries are present, and the treatment plan requires an orthognathic surgery as the main step to correct the canted occlusal plane The degree of OC relative to the true horizontal plane as measured cephalometrically in the frontal plane = the linear millimeter difference between the right and left medial canthus and the right and left canine tips. Midline The diagnosis of the upper and lower midlines position in cases of occlusal plane asymmetries must follow different rules, in comparison with symmetric cases: Usually there is incorrect axial inclination of the anterior teeth associated with the cant of the occlusal plane, therefore, in these cases the professional must measure the dental midline in the papillar region , either in the upper or lower arch With the incorrect angulation of the anterior teeth, caused by occlusal plane canting, the midline measured in the incisal border does not represent the correct center of that group of anterior teeth. After correcting the occlusal plane, the teeth are uprighted according to the papilla, and not according to the incisal area

17. OC Management Orthognathic surgery 01 02 Orthodontic ttt

18. Indication: In patients with dramatic OC Purposes: correct facial and maxillary midline deviation level the oral commissure obtain symmetric display of the canine teeth and correct chin deviation according to the normal facial midline procedures : 1- Orthognathic surgery 1 Single jaw surgery Segmental surgery or Lefort I osteotomy 2 Double jaw surgery Lefort I osteotomy+ BSSO or VRO 3 Distraction osteogenesis Maxillary vertical elongation. Distraction osteogenesis OC Management

19. In cases of canted occlusal plane, is essential to define which side should be intruded (Long side) or extruded (short side) to level the plane. Usually the upper arch serves as the reference to the diagnosis 1- Orthognathic surgery The selection of the side for vertical movement depends on : Maxillary incisor display OP angle in the sagittal direction Anterior vertical facial height. 1 Single jaw surgery Segmental surgery or Lefort I osteotomy 2 Double jaw surgery Lefort I osteotomy+ BSSO or VRO 3 Distraction osteogenesis Maxillary vertical elongation. Distraction osteogenesis OC Management It is considered that surgical intrusion of the maxillary complex is a more stable process than maxillary vertical elongation.

20. 2- Orthodontic ttt 1 Unilateral intrusion of the upper arch and extrusion of the lower arch Combination of intrusion and extrusion on both arches 3 Unilateral intrusion of the lower arch and extrusion of the upper arch 2 OC Management

21. When the diagnosis reveals good teeth and gingival display on one side of the upper arch and an excessive gingival display on the other side , this side must be intruded After intrusion on the upper arch, the arch must be held in position, whereas the lower arch is extruded with intermaxillary vertical elastics, which are connected directly to the upper arch or occasionally connected to the skeletal anchorage device Unilateral intrusion of the upper arch and extrusion of the lower arch 1 Indication:

22. In cases where the upper arch displays 100% of the crown without gingiva exposure in one side, whereas the other side the exposure of the crown is less than 100%, we should avoid intrusion on the upper arch, because the intrusion would reduce exposure on the good side, considerably impairing the aesthetics of the smile. In this case, the correction of the occlusal plane must begin with an intrusion on the lower arch, on the same side with reduced exposure of the crowns on the upper arch. After intrusion on the lower arch, this arch is stabilized, and the patient is advised to use vertical elastics on this side, to provoke the extrusion of the upper arch 2 Unilateral intrusion of the lower arch and extrusion of the upper arch Indication:

23. When one side on the upper arch displays no gingiva and less than 100% of the crowns, whereas the other side shows the entire crowns and excess of gingiva, the option should be the combination of intrusion on the side with excess, and extrusion of the side where the crowns are incompletely exposed . However, previously, an intrusion on the lower arch on this side is necessary. Therefore, the correction of canting in such cases must start with the intrusion on both arches. This option is preferably indicated in hyperdivergent patients , because only intrusive forces and little or no extrusive mechanics will be used. When the extent of the intrusion is the same on the upper and lower arches Extrusion on the opposite arch is unnecessary, because intrusion on both sides will correct the canting itself. When the extent of intrusion differs between the sides Vertical elastics might be occasionally necessary on one side to establish a good intercuspation. 3 Combination of intrusion and extrusion on both arches Indication:

24. Biomechanical considerations in treatment of OC 2 3 1 4 5 6 Consider removal of third molars in quadrants where intrusion is required Bond the second molars in the quadrant requiring intrusion Monitor the display of incisors and canine relative to lip line Choose the suitable mechanics and means of intrusion Intrusion timing should be taken into consideration Make control on the side effects of the mechanics

25. Various mechanics can be used according to severity of OC TMA wire w ith wavy configuration ( a combination of curve of Spee and reverse curve of Spee at the side view) 0.017 × 0.025 wire size is for the 18-slot size brackets, and 0.018 × 0.025 is for the 22-slot size brackets Asymmetric bends in the archwires Elastics Bite blocks High-pull headgears Mini-implants, bone screws and Miniplates Use of innovative archwire (Yin-Yang archwire ) liou etal 2019 Use of rhythmic wire system with miniscrews Kang etal 2010 Biomechanical considerations in treatment of OC

26. Biomechanical considerations in treatment of OC Inter-radicular miniscrews Mini-implants The insertion of both buccal and palatal mini-implants in the same interproximal space should be avoided.

27. Biomechanical considerations in treatment of OC Size: Range from 10 to 14 mm in length and a minimum diameter of 2 mm, also available as a short or a long collar. IZS: available in two sizes commonly (manufacturer specific) – 12 and 14 mm in length and 2 mm in diameter . When the soft tissue in the buccal vestibule is thick as in most clinical situations, the preferred choice is a 14 mm screw which have 7 mm of head and collar area and 7 mm of cutting spiral. When the soft tissue in the buccal vestibule is thin bone screws of 12 mm length are preferred. BSS: available in two sizes commonly (manufacturer specific) – 10 mm and 12 mm in length and 2 mm in diameter . the preferred choice will be a 12‑mm screw. Bone screws (IZS in maxilla and BSS in mandible)

28. Biomechanical considerations in treatment of OC Site for placement: Maxilla: Infra-zygomatic crest. Some authors (Lin) prefer bone screws to be placed in the 1st and 2nd molar region others ( Liou ) prefer a more anterior placement, closer to the MB root of the 1st molar Mandible: buccal shelf area, which lies lower and lateral to the 1st molar region Buccal shelf bone screws can also be placed in the external oblique ridge of the mandible if the buccal shelf area is found to be too thin or too deep Bone screws (IZS in maxilla and BSS in mandible)

29. Biomechanical considerations in treatment of OC Procedure: IZC (1st and 2nd molar region): Initial point of insertion is inter-dentally between the 1st and the 2nd molar and 2 mm above the muco-gingival junction in the alveolar mucosa. The self‑drilling screw is directed at 90° to the occlusal plane at this point. After the initial notch in the bone is created after couple of turns to the driver, the bone screw driver direction is changed by 55°–70° toward the tooth, downward , which aid in bypassing the roots of the teeth and directing the screw to the infra‑zygomatic area of the maxilla BS area of mandible (2nd molar region): Initial point of insertion is inter-dentally between the 1st and the 2nd molar and 2 mm below the mucogingival junction. The self‑drilling screw is directed at 90° to the occlusal plane at this point. After the initial notch in the bone is created after couple of turns to the driver, the bone screw driver direction is changed by 60°– 75 ° toward the tooth, upward Sometimes pre‑drilling or vertical slit in the mucosa is necessary if the bone density is too thick Bone screws (IZS in maxilla and BSS in mandible)

30. Biomechanical considerations in treatment of OC Bone screws (IZS in maxilla and BSS in mandible)

31. Biomechanical considerations in treatment of OC Bone screws (IZS in maxilla and BSS in mandible)

32. Insertion sites: Buccally: Several studies have revealed that the zygomatic buttress area is an efficient anchorage area for managing intrusion movement of the posterior maxillary segment. Palatally : On the midpalatal area , a miniplate with arms oriented toward the target teeth. Flap surgery was not necessary because the soft tissues on the midpalatal area were thin Mandible: At the buccal cortical bone around the apical regions of the lower first and second molars . Biomechanical considerations in treatment of OC Miniplates?

33. Biomechanical considerations in treatment of OC A flap elevated in the regions of the maxillary premolars and molars after a sulcular incision. A vertical corticotomy using piezosurgery and a round bur with a slow-speed hand piece performed between the first premolar and the second premolar with care not to damage the root apices. A horizontal corticotomy , 3 mm above the root apex from the premolars to the distal aspect of the second molar. A second vertical corticotomy performed distal to the second molar up to the alveolar crest Corticotomy-enhanced intrusion (speedy surgical orthodontics) of the posterior maxillary segment with miniplate anchorage is shorter. Shorter intrusion duration is advantageous in terms of the risk of devitalization and root resorption. aim of this technique is not tooth movement through the bone but rather bony block movement by compression osteogenesis. Miniplates?

34. Mini-implants or bone screws or miniplates ?

35. Biomechanical considerations in treatment of OC Mini-implants vs bone screws vs miniplates? Miniplates Bone screws Mini-implants receive a higher load, intrusion force of up to 400 g can be applied. Movements in more than one direction can be performed, reducing the total time of treatment No risk for root contacting with screws during the intrusion Indicated when canting is severe Receive a higher load (immediate loading is possible and a force of up to 300–350 g so sagittal correction can be made at the same side. Less failure rate (reports suggest overall failure rates of micro‑implants to be 13.5%while bones screws to be – BSS (7.2%) and IZC (7%). No risk for root contacting with screws during the intrusion No flap needed More cheap Less manipulation No flap needed No pre drilling Require flap elevation for insertion and removal. More expensive. Gingival overgrowth on the screw Solution: Oral hygiene maintenance – use screws with larger heads. Pre drilling needed in mandible. Pear load only from 50-200g No anteroposterior mechanics can be done, for example, Class II correction. Risk of root contact during intrusion. Not allow sufficient range of the activation of the intrusion mechanics indicated when occlusal plane canting is slight or moderate Poggio and colleagues recommended a minimum clearance of 1mm between a miniscrew and a root for both periodontal health and mini screw stability. Therefore, it can be concluded that miniscrews with a diameter of 1.5mm or less are safe for interradicular insertion if the space between the roots is at least 3.5mm .

36. Biomechanical considerations in treatment of OC Mini-implants vs bone screws vs miniplates? Miniplates Bone screws Mini-implants receive a higher load, intrusion force of up to 400 g can be applied. Movements in more than one direction can be performed, reducing the total time of treatment No risk for root contacting with screws during the intrusion Indicated when canting is severe Receive a higher load (immediate loading is possible and a force of up to 300–350 g so sagittal correction can be made at the same side. Less failure rate (reports suggest overall failure rates of micro‑implants to be 13.5%while bones screws to be – BSS (7.2%) and IZC (7%). No risk for root contacting with screws during the intrusion No flap needed More cheap Less manipulation No flap needed No pre drilling Require flap elevation for insertion and removal. More expensive. Gingival overgrowth on the screw Solution: Oral hygiene maintenance – use screws with larger heads. Pre drilling needed in mandible. Pear load only from 50-200g No anteroposterior mechanics can be done, for example, Class II correction. Risk of root contact during intrusion. Not allow sufficient range of the activation of the intrusion mechanics indicated when occlusal plane canting is slight or moderate

37. Biomechanical considerations in treatment of OC Mini-implants vs bone screws vs miniplates? Miniplates Bone screws Mini-implants receive a higher load, intrusion force of up to 400 g can be applied. Movements in more than one direction can be performed, reducing the total time of treatment No risk for root contacting with screws during the intrusion Indicated when canting is severe Receive a higher load (immediate loading is possible and a force of up to 300–350 g so sagittal correction can be made at the same side. Less failure rate (reports suggest overall failure rates of micro‑implants to be 13.5%while bones screws to be – BSS (7.2%) and IZC (7%). No risk for root contacting with screws during the intrusion No flap needed More cheap Less manipulation No flap needed No pre drilling Require flap elevation for insertion and removal. More expensive. Gingival overgrowth on the screw Solution: Oral hygiene maintenance – use screws with larger heads. Pre drilling needed in mandible. Pear load only from 50-200g No anteroposterior mechanics can be done, for example, Class II correction. Risk of root contact during intrusion. Not allow sufficient range of the activation of the intrusion mechanics indicated when occlusal plane canting is slight or moderate

38. Biomechanical considerations in treatment of OC Mini-implants vs bone screws vs miniplates? In conclusion, it can be argued that when maxillary molar intrusion is desired, miniscrews offer a reliable and less invasive approach, but miniplates are essential in cases where SARPE and posterior intrusion are used at the same time because the anchorage units need to be above the osteotomy cuts, and in cases where mandibular molar intrusion is required, miniplates are the better choice. The mandible is composed of thicker cortices than the maxilla which might suggest that it resists the intrusive force more than the maxilla Canting of OP Slight Miniscrew Severe Bone screw Miniplates

39. Biomechanical considerations in treatment of OC Mini-implants vs bone screws vs miniplates? In conclusion, it can be argued that when maxillary molar intrusion is desired, miniscrews offer a reliable and less invasive approach, but miniplates are essential in cases where SARPE and posterior intrusion are used at the same time because the anchorage units need to be above the osteotomy cuts, and in cases where mandibular molar intrusion is required, miniplates are the better choice. The mandible is composed of thicker cortices than the maxilla which might suggest that it resists the intrusive force more than the maxilla Canting of OP Bone screw Severe Miniplates Mandible When osteotomy is indicated for acceleration When surgical removal of third molar is indicated

40. Intrusion timing Biomechanical considerations in treatment of OC 01 Type 1 02 Type 2 when a plain archwire is applied, the angulations and inclinations of the affected teeth will be in the wrong directions, resulting in tilting of incisors and a worsening of buccolingual inclination of the posterior teeth The correction was started at the leveling stage to minimize the unwanted tilting of the anterior teeth during unilateral intrusion of the left maxillary posterior teeth A segmental surgery is the preferred choice for intrusion This option offers benefits such as reduced treatment time and good control of the buccolingual inclinations of the affected teeth. Another option is to place two TADs, one on the buccal side and one on the palatal, to unilaterally intrude the posterior teeth. Le Fort I maxillary surgery is the first choice. When non-surgical orthodontic treatment is necessary, it is suggested that intrusion of the maxillary posterior teeth be started after the leveling stage .

41. Buccal flaring of the intruded teeth: It occurs due to the distance from the point where the force is applied and the center of resistance of the group of teeth, creating a moment of force and moving the crowns buccally . A tendency for crossbite is commonly observed on the opposite side, due to the rotation of occlusal plane, moving the crowns lingually on this side. Solution: 1- Use transpalatal bar (TPB), which avoids the overexpansion of the arch on the side of intrusion and aids in controlling the torque on both sides. 2- Buccal and palatal TAD , thereby eliminating the need for TPB to control side effects on that side. 3- During the intrusion, the use of 0.019 × 0.025-in stainless steel archwire is essential, allowing the control of the torque, with an accentuated buccal root torque on the side of the intrusion, whether a lingual root torque must be inserted on the opposite side , avoiding the tendency for crossbite . 4- If the intrusion is performed on the lower arch, a lingual arch is the option to avoid the same side effects, associated with the same rectangular archwire and torque control as in the upper arch. Biomechanical considerations in treatment of OC Controlling side effects

42. lingual crown movement on the extruded teeth The most common way for extrusion is the use of vertical elastics connecting the intruded teeth to the opposite arch or connecting the skeletal anchorage device to the opposite side. Solution: Use 0.019 × 0.025 -in rectangular stainless steel archwire . A lingual root torque must lie on the side of the extrusion, avoiding the lingual inclination of the crowns and buccal root torque on the opposite side , and avoiding the crossbite tendency on the other. Biomechanical considerations in treatment of OC Controlling side effects

43. Vertical side effects as roller coaster bucking and lateral open bite Solution: Ensure that second molar bonded when fully erupted avoid application of traction with a flexible archwire Vertical settling elastics are used to close open bite by extrusion of the opposing arch. Biomechanical considerations in treatment of OC Controlling side effects

44. Relapse of the intruded molars Solution : Leave the miniscrew , or the miniplates for 3 months after intrusion so it can be used in case of relapse. Make extrusion of the opposing arch directly on the miniscrew instead of the intruded teeth to avoid any risk of extrusive relapse. Make stabilization of the intruded molars by fixing them to the miniscrew if elastics will by used directly on them. Three months full-time wear of plastic retainers with whole arch occlusal coverage. These should prevent early molar extrusion after debond . Biomechanical considerations in treatment of OC Controlling side effects

45. References