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Prosthodontic management


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Prosthodontic management

  1. 1. Prosthodontic management of mandibular defects INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. Contents      Introduction Classification of mandibular defects Factors affecting treatment of mandibulectomy patients Relating surgical and prosthetic considerations in mandibulectomy patients Management of mandibulectomy patients - Use of processed bases - Method of recording denture space - Removable partial denture considerations in mandibulectomy patients - Treatment of mandibular deviation
  3. 3.     Different types of prosthesis used for mandibulectomy patients - Guide flange prosthesis - Maxillary occlusal table - Maxillary inclined plane - Palatal augmentation prosthesis - Implant retained prosthesis Gunnings splint and stent prosthesis Summary and Conclusion References
  4. 4. Introduction
  5. 5. Classification of mandibular defects Based on etiology Acc to Laney(1979) 1.Acquired: - Marginal - Segmental - a) Lateral to midline - Body only - Ramus- Body with disarticulation b) Anterior body - Subtotal - Total
  6. 6. 2. Congenital - Incomplete formation - Incomplete ossification eg) hypoplasias, mandibulofacial dysostosis,etc 3. Developmental as a result of postnatal insults eg) trauma during birth, surgery,etc
  7. 7. Acc to amount of resection (Laney)  Continuity defect (marginal resection)  - Inferior border and its continuity preserved - No deviation Discontinuity defect (segmental resection) - Complete segment of mandible from alveolar crest to inferior border removed - Less facial disfigurement - Mandible deviates to resected side - Occlusion rarely changed - Marked facial disfigurement - Can be :- anterior defect posterior defect - Occlusion altered - Can be :- lateral discontinuity defect midline discontinuity defect
  8. 8. Acc to Cantor and Curtis (1971) Class 1 : Radical alveolectomy with preservation of mandibular continuity
  9. 9. Tissues resected : - Portion of alveolar process and body of mandible - Lingual and buccal sulcus mucosa - Portion of base of tongue and mylohyoid muscle - Lingual and inferior alveolar nerves - Sublingual and Submaxillary salivary glands - Sometimes anterior part of digastric muscle FEATURES 1. Least debilitating. 2. Sometimes resection of part of mylohyoid muscle and resultant scarring can raise the floor of the mouth causing reduction in tongue mobility. 3. Ability to shape and control the tongue may be lost due to loss of some intrinsic muscles. 4. Resection of lingual and inf alveolar nerve results in loss of sensation to mucosa of cheek,alveolar process,lower lip and loss of taste on anterior 2/3rd of the tongue.
  10. 10. Class 2 : Lateral resection of mandible distal to cuspid
  11. 11. Tissues resected: - condyle, ramus and body of mandible distal to cuspid - mylohyoid, hypoglossal,anterior belly of digastric, internal pterygoid,masseter,external pterygoid, pharangoglossal and palatoglossal muscles, most of intrinsic muscles of tongue. - hypoglossal , lingual and inferior alv nerves - adjacent buccal and lingual mucosa FEATURES 1 Speech, swallowing, saliva control, manipulation of food impaired. 2. Facial disfigurement apparent 3. Disarticulation and loss of muscles of mastication will hamper mandibular movements 4. Taste ,sensory and motor losses more extensive as compared to class 1
  12. 12. Class 3 - Lateral resection of the mandible to the midline
  13. 13.  Tissues resected : all those described in class 2 in addition to the anterior portion of the mandible, geniohyoid, genioglossus, remaining portion of mylohyoid muscle with lingual and buccal mucosa. FEATURES 1. Restricted tongue mobility due to loss of tip of tongue and genioglossus muscle 2. Speech, swallowing,saliva control and manipulation of food severely restricted. 3. Facial disfigurement is worse due to loss of anterior part of mandible 4. Disarticulation and reduction in amount of basal bone reduce prosthodontic prognosis. 5. Scarring of orbicularis oris can interefere with expression of emotion
  14. 14. Class 4: Lateral bone graft surgical reconstruction
  15. 15.   Lateral bone and split thickness skin or pedicle graft can be performed on patients who have had: - radical alveolectomies - resection of mandible distal to cuspid with or without disarticulation. 3 types of bone grafts are possible 1. Mandibular augmentation procedures. 2. Bone graft that connect a residual condyle with the larger mandibular fragment. 3. Lateral bone grafts that extend from the mandibular fragment into the defect area to establish a pseudo TMJ.
  16. 16. Class 5 :Anterior bone graft surgical reconstruction
  17. 17.  Tissues resected at time of orignal operation: - anterior portion of the mandible - large bilateral portions of mylohyoid, geniohyoid genioglossus and anterior digastric muscles - bilateral lingual and inferior alv nerves - bilateral submaxillary and sublingual salivary glands - mucosa of lower lip - anterior floor of mouth - ventral surface of tongue The mucosa retained in the labial and buccal regions is sutured to the residual stump of the tongue and a krischner wire is often positioned to maintain the mandibular fragments . Bone graft and split thickness skin graft or pedicle graft procedures can be is used to restore anterior facial contour and bilateral mandibular function.
  18. 18. Class 6: Resection of anterior portion of the mandible without reconstructive surgery to unite lateral fragments
  19. 19. Factors affecting treatment of mandibulectomy patients 1.Location and extent of mandibular defects Radical alveolectomy Least debilitating Main problems – loss of vertical ridge height and vestibular depth Vertical discrepancy most important when prosthesis supported by dental implants is considered.
  20. 20. Discontinuity defects RULE OF THUMB:-The farther anterior the defect, the more disfiguring and functionally debilitating it is likely to be. Defects of the symphyseal region
  21. 21. Most debilitating and difficult to treat. Greatest facial disfigurement. Surgical reconstruction necessary or at least segmental stabilization before prosthodontic treatment can be initiated. Mandibulectomy defects in the molar region more well suited for surgical reconstruction compared to anterior defects. If muscle attachments are intact – Good prognosis Near normal appearance and function is achievable.
  22. 22. 2. Presence of remaining natural teeth/pre-existing implants Pts after mandibulectomy present with few or no remaining natural teeth. 2 reasons: 1. Pts with greatest risk of sq cell carcinoma are heavy users of tobacco and alcohol. 2. Teeth are usually extracted prior to radiotherapy to prevent complications such as osteoradionecrosis. Greater the number of teeth ,better the prognosis. Maximum number of abutment teeth should be incorporated in the design of the prosthesis to maximise stability and dissipate functional forces
  23. 23. Ideal for rehabilitation
  24. 24. A maxillary complete denture will function well for a mandibulectomy patient against a reconstructed mandibular dentition Exceptions: Collapse of residual proximal mandibular stump against the posterior maxillary alveolus prohibiting adequate denture flange extension. When a guide flange prosthesis is planned for treatment of mandibular deviation
  25. 25. 3.Degree of post mandibulectomy rotation and deviation Deviation towards the defect and rotation of mandibular occlusal plane inferiorly Deviation: Primarily due to loss of tissue involved in surgical resection.
  26. 26. Rotation:Due to - Pull of the suprahyoid muscles on the residual fragment causing inferior displacement and rotation around the fulcrum of the remaining condyle. - Gravity. Loss of anchorage of elevator muscles.     Sequelae Facial disfigurement Loss of occlusal contact Loss of ability to bring lips together Drooling of saliva and difficulty to initiate swallowing process
  27. 27.    Prosthodontic prognosis in such patients can be improved by early post resection physical therapy to reposition the mandibular fragment to a more normal position and to minimize scar formation that will make deviation more severe. Should be carried out as early as possible.After 6-8 weeks post operatively it will not be as beneficial. Can be in the form of 1.Physical therapy carried out by the patient himself 2.Mandibular resection guidance prosthesis
  28. 28. 5.Available mouth opening Trismus –due to surgical trauma Physical therapy should be started immediately. Scar tissue formation will further reduce mouth opening. Simple test to check mouth opening:Insert a stock mandibular impression tray in the mouth.If this cannot be accomplished rehabilitation will be less than satisfactory. Surgical intervention
  29. 29. 6.Functional limitation of tongue - Frequently the surgical wound is closed by suturing the remaining tissues of the floor of the mouth or tongue to the remaining buccal tissues.
  30. 30. This compromises: - Speech - Swallowing - Mastication - Control of food bolus - Ability to control removable prosthesis - Lingual vestibuloplasty and skin or mucosal grafting can be used to improve tongue mobility - Evaluation of tongue mobility - In patients whom anterior resection has been done, ability to lick the lips when the artificial prosthesis is placed in the mouth may be difficult (due to loss of genioglossus muscle)
  31. 31. In such cases consideration is given to lowering the anterior occlusal plane or arranging the teeth slightly lingually.   Speech therapy Loss of innervation will compromise tongue function and prognosis of prosthodontic rehabilitation. If lingual nerve is sacrificed during resection, the tongue on the defect side will permanently remain without any feeling. Loss of sensory capability:- Affects speech Mastication Prosthesis control Loss of sensory innervation of the buccal mucosa(long buccal nerve) and lower lip(mental nerve) will reduce patients ability to control food and saliva
  32. 32.
  33. 33. 7.Compromise of vestibular extensions  Vestibular depth is critical for stability and peripheral seal It is also critical when mandibular continuity is restored with bone grafting and implants are considered.
  34. 34. 8.Skin grafting  Skin grafts are used for surgical reconstruction either as lining for the surface of resected soft tissue or as part of skin and connective tissue grafts such as pedicle flaps, free flaps etc. Advantages 1. Effective load bearing tissue. 2. Can withstand pressure and chafing from prosthesis. 3. Protects underlying bone and connective tissue well due to rapid turnover of keratin producing cells. Disadvantages 1. No sensory innervation. 2. Full thickness grafts may incorporate hair follicles. 3. Skin is not very compatible with titanium surface of implants.
  35. 35. 9.Radiation therapy   Careful treatment planning is required for patients with radiation therapy Irradiated tissue is fragile ,sensitive to manipulation,dessicated,slow to heal,prone to infection and at risk of osteoradionecrosis
  36. 36. 10. Altered anatomic relationships following restoration of mandibular continuity  Reconstruction of anterior defects Most difficult situation for grafting and frequently results in a graft that is deficient anteriorly. - Results in a severe Class 2 like situation. The prosthodontic difficulties seen in rehabilitating such a patient are:- Inability to provide proper lip support. - Speech problems associated with mandibular dentition placed too far lingually. - Inability to control food bolus due to lack of motor function of lips and lower part of the face.
  37. 37. - Excessive display of mandibular teeth due to patients inability to maintain normal lip posture. - Difficulty gaining adequate space for prosthesis placement without encroaching on function of tongue. - Misalignment of remaining unresected mandibular fragments and resultant relationship between maxillary and mandibular teeth.  Reconstruction of posterior defects - More predictable from prosthodontic point of view as compared to anterior defects. - The mediolateral positon of the graft is frequently seen lateral to the orignal position of the mandibular body. Thus the prosthesis must be built in cross bite to maintain the denture teeth over the supporting base of the bone graft.
  38. 38. Angled dental implants Inadequate space after surgical reconstruction Excessive space after surgical reconstruction
  39. 39. Relating surgical considerations to prosthodontic treatment Marginal mandibulectomy Soft tissues are mainly used to reconstruct marginaL mandibulectomies They may be: - Skin graft - Local flap - Pedicle flap - Microvascular free flaps  Skin grafts are ideal for prosthetic reconstruction. However when soft tissue bulk is required or recipient bed is previously irradiated microvascular free flaps are the treatment of choice.
  40. 40.  Discontinuity defects Previously soft tissue local flaps(mainly the residual tongue sutured to the border of the defect) and pedicle flaps (pectoralis muscle) were used. MVFF have revolutionized the treatment of discontinuity defects. Microvascularized bone is mainly obtained from: 1.Fibula- most common 2.Iliac crest Soft tissue MVFF are obtained from 1.Forearm 2.Rectus muscle
  41. 41. Mandibular malposition after bony reconstruction May be due to: 1. Minimal proximal mandible on the surgical side to attach the bone graft. 2. Mandibular segments are not stabilized and maintained in their pre-operative relation to each other during grafting procedures. 3. Delayed reconstruction may not be able to overcome scar tissue formation completely. 4. The bone grafts used i.e the fibula and the iliac crest graft have some inherent problems: - Lacks height compared to the residual mandible 
  42. 42. - Pyramidal in shape bieng narrower at the occlusal surface - Grafted to restore inferior border of the mandible which is necessary to restore facial form.This places it bucally in the plane of the cheek. - Since bone is placed bucally in the cheek implants distal to the premolar area cause constant soft tissue and infection problems
  43. 43.  Management of mandibulectomy patients Processed bases    Necessary due to loss of supporting bone ,unusual intra-oral contours,gross malposition of occlusal contacts. Allow the determination of the relationship of the final prosthesis periphery and the buccal or lingual tooth position. Recording maxillo-mandibular relationship with processed bases allow the clinician to evaluate retention and stability proir to adding wax rims or dentition.
  44. 44.    Significant loss of alveolar bone as well as rotation and deviation of the mandible postoperatively make it necessary for the record bases to be as stable as possible during maxillomandibular records. Extension beyond the periphery of the prosthesis may be required to support the lip.To add stability to the prosthesis,occlusal contact may need to be significantly buccal or lingual to normal anatomic landmarks that usually denote the occlusal table. Pts who have implant retained prosthesis should have retentive elements incorporated in the processed bases.This gives the clinician an early idea as to the support that can be gained for the soft tissues of the face
  45. 45. Methods of recording denture space   Shifman and Lepley(1982):Neutral zone or denture space concept for marginal mandibulectomy patients. They supported this by quoting Fish(1933) and Brill(1965)
  46. 46.
  47. 47.  Cantor and Curtis(1971):Swallowing technique in edentulous patient
  48. 48.
  49. 49. Partial denture design in mandibulectomy patients  Kelly(1965):described the advantages of using combination clasps in mandibulectomy patients.He also described a double bar type of stress breaker which helped maintain the partial denture in place.
  50. 50.
  51. 51.
  52. 52. Management of mandibular deviation Review of literature   Ackerman(1955) advocated the use of intermaxillary fixation or a guidance prosthesis immediately post operatively.The prosthesis used a gate hinge clasp for maximum stability during function.This design is similar to the swing lock partial denture design. Adisman(1962) fabricate guide plane splints that were used as postoperative intermaxillary splints. After healing the fixed prosthesis was replaced by a mandibular removable partial denture guide plane.The RPD framework was made of cast metal with a acrylic resin or heavy wire loop that extended into the mucobuccal fold and functioned against the maxillary posterior teeth
  53. 53.    Scanell(1965) stated that a mandibular resection patient should be seen by a dentist within 7-10 days.He noted that a corrective guide flange prosthesis inserted early can avoid later difficulty in mandibular movement. Swoope (1969) while treating edentulous mandibular resection patients formed a palatal ramp on the maxillary denture to broaden the occlusal table and make it easier for the patient to obtain stabilizing occlusal contacts. Schaff(1976) described a removable partial denture flange prosthesis for the patient with natural teeth. In partially edentulous patients if teeth are strong enough, a mandibular cast removable partial denture flange prosthesis can be used to reduce mandibular deviation.
  54. 54.    Armany and Meyers (1977) advocated use of intermaxillary fixation at time of surgery for 5-7 weeks.For dentulous patients if mandibular deviation is observed after fixation, a guide flange prosthesis can be used until the patient returns to intercuspal position. Desjardins(1979) stated that in dentulous patients a maxillary palatal inclined plane palatal to the posterior teeth on the non defect side can be used as a training device for mandibular movement. This device is only suitable for dentulous patients. Chalian et al(1979) indicated that a guide plane prosthesis must be used if the resection includes the body of the mandible, ramus and condyle.These prosthesis consist of a maxillary and mandibular cast removable partial denture framework. A lower inverted U shaped flange slides against a upper horizontal bar on the non defect side.
  55. 55. Mandibular guide flange prosthesis
  56. 56. Maxillary occlusal table Maxillary inclined plane prosthesis
  57. 57. Palatal augmentation prosthesis Implant retained prosthesis
  58. 58. Gunnings splint Stent prosthesis
  59. 59. Summary and Conclusion
  60. 60. References       Ackerman AJ The prosthodontic management of oral and facial defects J Prosthet Dent,1955;5:413-432 Scannel JB Practical considerations in dental treatment of patients with head and neck cancer J Prosthet Dent,1965;15:764-778 Kelly EK Partial denture design applicable to the maxillofacial patient J Prosthet Dent,1965;15:168-173 Swoope CC Prosthetic management of resected edentulous mandibles J Prosthet Dent,1969;21:197-201 Cantor R and Curtis TA Prosthetic management of edentulous mandibulectomy patients Part 1 J Prosthet Dent,1971;25:447455, Part 2 J Prosthet Dent,1971;25:547-555, Part 3 J Prosthet Dent,1971;25:671-678. Schaff NG Oral reconstruction for edentulous patients after partial mandibulectomies J Prosthet Dent,1976;36:292-297
  61. 61.         Armany MA and Meyers EN Intermaxillary fixation following mandibular resection J Prosthet Dent,1977;37:437-443 Desjardins RP Occlusal considerations in partial mandibulectomy patients J Prosthet Dent,1979;41:308-311 Shifman A and Lepley JB Prosthodontic management of postsurgical soft tissue deformities associated with marginal mandibulectomies J Prosthet Dent,1982;48:178-183 Clinical maxillofacial prosthetics, Thomas D Taylor;1 st edition Maxillofacial prosthetics, Varoujan A Chalian Maxillofacial prosthetics, postgraduate dental hand book series,Vol 4 William R Laney Removable partial prosthodontics,Alan B Carr;11th edition Clinical removable partial prosthodontics,Kenneth L Stewart;2 nd edition
  62. 62.