Class iii


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Class iii

  1. 1. دائرة صحة ديالى<br />المركز الصحي التخصصي لطب الاسنان في بعقوبة<br />وحدة التقويم<br />class III malocclusion<br />اعداد<br /> الدكتورة هند رعد حسون (طبيبة اسنان/مقيمة دورية)<br />الدكتورة دعاء خالد علوان (طبيبة اسنان/مقيمة دورية)<br />الدكتور مصطفى عبدالكريم (طبيب اسنان/مقيم دوري)<br />اشراف<br />الدكتورة بسمة محمد حمد <br />(ماجستير تقويم اسنان)<br />28/09/2010<br />
  2. 2. Content:<br />1.introduction<br />2.etiology<br />3.skeletal and dental factors<br />4.occlusal feature<br />5.classification<br />6.treatment<br />7.surgical treatment<br />8. future innovative techniques for class III treatment<br />9.Conclusion<br />10.Reference<br />
  3. 3.   Introduction<br />The Skeletal Class III malocclusion is characterized by mandibularprognathism, maxillary deficiency or both. Clinically,these patients exhibit a concave facial profile, a retrusivenasomaxillary area and a prominent lower third of the face.The lower lip is often protruded relative to the upper lip.The upper arch is usually narrower than the lower, and the overjetand overbite can range from reduced to reverse. The effect of environmental factors and oral function on theetiological factors of a Class III malocclusion is not completelyunderstood. However, there is a definite familial and racialtendency to mandibular prognathism. For many Class III malocclusions,surgical treatment can be the best alternative. Depending onthe amount of skeletal discrepancy, surgical correction mayconsist of mandibular setback, maxillary advancement or a combinationof mandibular and maxillary procedures. After surgical correctionof the skeletal discrepancy, the occlusion is usually finishedorthodontically to a Class I relationship. However, if surgicaltreatment is not performed, and the final molar relationshipis Class III or Class I, there are challenges specific to thestatic and functional Class III occlusion that must be considered. Sometimes a Class III relationship is caused by a forward shiftof the mandible to avoid incisal interferences. This is a pseudo-ClassIII malocclusion. In these cases, it is important to establish the<br /> <br />
  4. 4. inter-occlusal relationship with the teeth in the retruded contact position.The british standards definition of class III incisor relationship includes those malocclusions where the lower incisor edge occludes anterior to the cingulum plateau of the upper incisors. Anteroposterior 'sagittal‘ discrepancy in here is less than normal or possesses a –ve vertical relationship, if dentally then the O.J. =1mm or less up to –ve, and if a skeletal classIII discrepancy then the ANB angle =1degree and less depend upon severity.<br />
  5. 5.
  6. 6. Etiology :<br />1.early closure of the nasomaxillary complex sutures in certain syndromes.<br />2.hereditary ,small size maxilla and big size mandible.<br />3.collapsed maxilla for cleft lip and palate patients.<br />4.mouth breathing individuals.<br />5.environmental,collapse of maxilla occur when extraction of multiple permanent teeth occur early in life.<br />
  7. 7. Skeletal pattern:<br />
  8. 8. Mandibular, maxillary ,and cranial base factors make a combined :contribution to the underlying classIII skeletal through <br />1.Usually Class III associated with along mandible<br />2.forward placement of the glenoid fossa positioning the mandible more anteriorly<br />3.short and/or retrognathic maxilla<br />4.short anterior cranial base or a combination of these.<br />the vertical relationship of the skeletal bases varies from increased to average or reduced and is generally reflected in the depth of overbite, which may alter depending on the pattern of facial growth. Where this is vertical rather than horizontal ,an anterior open bite is likely.<br />Commonly ,a transverse discrepancy exists in the dental base relationship because of the narrow maxillary and wider mandibular bases ,although this is often worsened by the classIII skeletal pattern.<br />And again the problem may be limited to dentition alone by:<br />A-proclination of lower anterior teeth <br />B-retroclination of upper anterior teeth.(or both)<br />
  9. 9. SOFT TISSUE:<br />The soft tissue surrounding play a very minor effect in the etiology of class III malocclusion when compared with their effect in class II malocclusion.<br />Where the lips competent, the lips and tongue induse retroclination of the lower incisors and prolination of the upper incisors (dentoalveolar compensation). Where the lower anterior facial height is increased the lower lips are frequently incompetent, with an adaptive tongue thrust on swallowing which may procline the lower incisors.<br />In sagittal direction except in sever skeletal III cases with mandibular protrusion ,lower lip will act to retroclined the lower anterior teeth and change their inclination.<br />
  10. 10. DENTAL FACTORS:<br />
  11. 11. Crowding is more common and more sever in the upper than in the lower arch ,often resulting from the difference in length and width of the arches. The upper frequently is short and narrow compared with a longer and wider lower arch.<br />OCCLUSAL FEATURE:<br />
  12. 12. • 1.The lower incisor edge lie anterior to the cingulum plateau of the upper incisors, the overjet is reduced or reversed' (british standards institute classification)<br />• 2.The overbite may be increased ,average ,or reduced. Where the vertical facial proportions are increased ,there is often an anterior open bite.<br />• 3.Frequently, the upper incisors are proclined and the lower incisors retroclined, compensating for the underlying classIII skeletal pattern.<br />• 4.Upper arch crowding is common, often because of a short and narrow dental base, while the lower arch is more commonly aligned or spaced.<br />• 5.Crossbite of the labial and/or buccal segments are common, resulting from the underlying classIII occlusal discrepancy as well as from differences in the length and width of the arches. Cross bite may be associated with a mandibular displacement particularly where a unilateral buccal segment crossbite exists. In the case of anterior cross bite, the possibility of displacement should be assessed by checking if relationship. <br />
  13. 13. THE MAIN VARIANTS IN –VE SAGITTAL OR CL III are:<br />Degree of skeletal discrepancy.<br />Degree of improper anterior teeth position and inclinations that lead to a –ve o.j.<br />If there are other discrepancies rather than sagittal in the other two directions or within the arch.<br /> <br />
  14. 14. Many classifications of severity of class III had been reviewed, the accepted one as follow:- <br />1.mild CL III 'dental' :<br />O.J. is purely dental due to different axial inclination of U/L anterior teeth or one of them ,O.J.=(0,-1,-2 mm)<br />2. moderate CLIII 'dento-skeletal' :<br />In which the cause of the reverse O.J. may be attributed partly to jaws and the other part to teeth together O.J.=<br />(-1,-2,-3 mm)<br />3.sever CL III 'SKELETAL' :<br />In which the cause of the reverse O.J. is a result of improper positions i.e. the maxilla is retruded and the mandible is protruded 'one of them or both '. in this situation orthognathic surgery is the solution of this discrepancy with the help of the orthodontist.<br />
  15. 15.  <br />TREATMENT OF CL III MALOCCLUSION:-<br />Treatment Planning:<br /> <br />Consider the degree of 1.anteroposterior and vertical skeletal discrepancy,<br />2. the potential direction and extent of future facial growth,<br />3.incisor inclinations,the amount of overbite,<br />4.the ability to achieve edgeto-edge incisor relationship,<br />5.and the degree of upper and lower arch crowding. <br />
  16. 16. According to the classification the treatment of type 3 by surgery while type 1&2 the postural can be treated orthodontically alone after removing or treating the cause by:-<br /> <br />1.proclination of upper anterior teeth<br />2.retroclination of lower anterior teeth<br />The amount of both movement may be limited or accepted or one of them .<br />such movement can be performed by removable appliance via:<br />
  17. 17. a. R.Z.springs for proclination or screws .<br />b.Hawley arch for retroclination &also can be done by fixed appliance<br />
  18. 18. 3.the use of class iii elastics <br />
  19. 19. That are attached to U/L fixed appliances extending from the upper molars to lower canines, that when the patient open and close the mouth there will be a stretching thus a reciprocal teeth movement will occur by sliding the upper arch anteriorly and the lower arch posteriorly.<br />
  20. 20. 4.Treatment by growth modification: <br />Myofunctional appliances:-<br />REVERSE-PULL HEADGEAR<br />'trade mark' Chin Cap <br />
  21. 21. Long time ago the age of 8 years was regarded as the time when an individual meet the orthodontist for the first time to evaluate his/her condition. Nowadays the age is 4 years where the orthodontist can predict that the patient will develop a malocclusion in the future and especially CLIII susceptible individuals.<br />The 'trade mark' Chin Cap is preventive myofunctional appliance that is used to prevent ,modify or break the unwanted downward and forward growth of the mandible by directing the force by the chin cap across the growth center of the mandible "condyle"back ward and upward bilaterally. the time elapsed to wear the chin cap is 12-16 hours per day and should last until adulthood or late adolescent by the age of 15-16 years.<br />
  22. 22. REVERSE-PULL headgear Also known as a face-mask, is used to apply an anteriorly directed force via elastics, on the maxillary teeth and maxilla. Although some have claimed that this appliance can change the position of maxilla, avery cooperative patient is necessary in view of the prolonged daily wear equired, often over several years. Nevertheless ,this technique is occasionally useful in the management of class iii malocclusion ,particularly those associated with a cleft lip and palate anomaly, and also in cases of hypodontia where forward movement of the buccal starting point to use the chin cap can be done as soon as the lower permanent incisors erupt ,and even we can use it before puberty to assist treatment of cl iii.segment teeth to close space is desirable.<br />
  23. 23. is one of the series of frankle appliance that is used to correct cl iii as soon as possible if the case demands the use of such appliance. Again it can be used as early as 7 years if the patient can tolerate its use.<br />In treatment of cl iii the correction of the OB &OJ &the canine relationship beside the correction of the crowding &x-bite if present is more important than the correction of the molar relationship. if an additional malocclusion feature is associated (compartment A) then the line of treatment is modified to overcome and treat the case simultaneously, i.e. post. x-bite ,open bite others.<br />
  24. 24. 5."postural class III" :<br />Pre treatment<br />
  25. 25. Since the borders between the normal CL I relation and the abnormal CL III cases and in such cases a cl I at the primary dentition and when the eruption of permanent dentition take place especially the anterior teeth, they appear edge to edge and then a translocated to a reverse O.J. relationship, such postural relationship (centric occlusion not coincident with the centric relation) i.e. when the dentist guide the mandible to the centric occlusion only a premature contact occur in the incisors leaving the posterior teeth with no occlusion and when a maximum posterior occlusion is needed to grind the food the mandible is shifted anteriorly and a reverse O.J. which is the cross bite.<br />
  26. 26. The treatment in this case is simple if done as early as possible when discovered and give an excellent results by correcting the reverse O.J. by using a fixed or removable appliance . In patients presenting with a deep overbite, a mandibular Hawley appliance with an anterior labial bow can be used to prevent forward movement of the lower incisors during bite jumping. In most cases crossbite correction is maintained by the overbite, and no retention appliance is necessary.<br />Post treatment<br />
  27. 27. Severe Class III skeletal pattern: <br />Surgical treatment:<br />the prensece of a reduced overbite or an anterior open bite preclude orthodontics alone, and surgery is necessary to correct the underlying skeletal discrepancy. That surgery is almost required if the value for the ANB angle is below -4 and the inclination of the upper incisors to the mandibular plane is less than 83*. The cephlometric finding should be considered and the patient's facial appearance. With those patients who have sever skeletal pattern with lack of overbite, a surgical approach should be explored before any permanent extractions are carried out, and preferably before any appliance treatment. The reason for this is that management of class iii malocclusions by orthodontics alone involves dento-alveolar compensation for the underlying skeletal pattern.Any dento-alveolar compensation must first be removed or reduced. <br />
  28. 28. For example, if lower premolars are extracted in an attempt to retract the lower labial segment but this fails and a surgical approach is subsequently necessary, the presurgical orthodontic phase will probably involve proclination of the incisors to a more average inclination with reopening of the extraction spaces. This is a frustrating experience for both patient and operator.<br />The prevalence of class III malocclusion in our community is less when compared with the class II malocclusion ,it's prevalence from 3% to 7% as a maximum occurrence.<br />
  29. 29. FUTURE INNOVATIVE TECHNIQUES FOR CLASS III TREATMENT<br />1.Distraction Osteogenesis to Advance the Maxilla:<br />
  30. 30. Distraction osteogenesis has recently been used to simulate a Le Fort I maxillary advancement and anterior segmental repositioning. An incomplete osteotomy placed above the canine and molar roots was performed through a vestibular incision. Pterygomaxillary disjunction and dissection of the nasal floor and septum were not performed. Distraction forces were placed on the maxilla by a reverse-pull headgear and an intraoral orthopedic appliance to advance the maxilla 8 to 12 mm. An incomplete osteotomy placed above the canine and molar roots was performed through a vestibular incision. Pterygomaxillary disjunction and dissection of the nasal floor and septum were not performed. Distraction forces were placed on the maxilla by a reverse-pull headgear and an intraoral orthopedic appliance to advance the maxilla 8 to 12 mm.<br />
  31. 31. 2.Dental Onplants to Provide Absolute Anchorage for Maxillary Protraction:<br /> <br />
  32. 32. One of the limitations in maxillary protraction with tooth-borne anchorage devices such as expansion appliances and palatal arches is the loss of dental anchorage (i.e., compensatory dental changes), especially with prolonged maxillary protraction. These undesirable effects include the loss of arch length, forward movement of maxillary molars, and proclination of the maxillary incisors. These dental changes can be minimized or even eliminated with the use of a novel device called maxillary onplants.100 The onplant comes as a disk, textured and coated with hydroxylapatite. The onplant can be placed on the palatal bone. After osseointegration is complete, forces can be applied to the teeth from the onplant palatal anchorage. Apart from providing a stationary orthopedic anchorage. To date, this new device has been placed on four orthodontic patients to distalize the maxillary posterior segments with no anchorage loss and minimal morbidity. The potential for using this new device as anchorage for maxillary orthopedics is promising.<br />
  33. 33. Conclusion:<br />At the end of this period in all cases the correction of anteriorcrossbite and the elimination of the mandibular displacementwere obtained, The goals of this approach are as follows:<br />1.prevents unfavourable growthespecially mandibular protrusion;irreversible, soft tissue 2.prevents habits such asbruxism;<br />3.eliminates traumatic occlusion and anterior crossbite;<br />4.providing more pleasing facial esthetics. 5.improving skeletal discrepancies and providing a more favorable6.environment for future growth<br />The disadvantages of this treatment include the following:<br />1.thefinal alignment of the teeth, is impossible without fixedappliance;2.cooperation from the patient is essential for the successofthis approach.<br />The positive factors include good facial esthetics, mild skeletal disharmony,no familial prognathism, convergent facial type, symmetric condylar growth. <br />The negative factors include poor facial esthetics, severe skeletal disharmony, familial pattern established, divergent facial type, asymmetric growth.<br />
  34. 34. thankyou….<br />Thank you….<br />