1. Introduction2. Objectives3. Alveolar atrophy4. Diagnosis & treatment planning5. Ridge correction procedures a) Alveoloplasty b) Mylohyoid reduction c) Tuberosity reduction d) Genial tubercles reduction e) Removal of tori f) Removal of exostoses g) Removal of undercuts6. Ridge augmentation7. Conclusion8. References
∆ Preprosthetic surgery refers to the surgical procedures that can modify theoral anatomy to facilitate the retention of conventional dentures.∆ According to the Glossary of Prosthodontic Terms (7), preprostheticsurgery is defined as surgical procedures designed to facilitate fabricationor to improve the prognosis of prosthodontic care.∆ According to Bruce Donoff, preprosthetic surgery is that part of theoral and maxillofacial surgery designed to establish the best hard andsoft tissue bases for prosthetic appliances.
∆ Elimination of disease∆ Conservation of oral structures∆ Provide residual tissue to withstand masticatory forces∆ Maintain function∆ Esthetics
∆ The term alveolar atrophy refers to the regression of theteeth-supporting, crescent-shaped osseous part of the upper andlower jaw.
Patterns of bone loss ∆ The results of Talgren’ s studies indicate that changes under the denture base more often occur in the mandible.(4:1) ∆ The difference in resorption of the jaws increases within the first year of denture wearing, which proves that the mandible cannot resist the strong bite forces under the denture base. ∆ According to Klemetti initially resorption starts on the alveolar part of the mandible, and the rest of the mandible remains unchanged. ∆ Resorption is faster in the labial and buccal parts of the alveolar ridge.(Resorptive Changes of Maxillary and Mandibular Bone Structures; Dubravka Knezovi et al, ActaStomat Croat 2002; 261-265)
Class Characteristics Treatment I Alveolar ridge (AR) adequate in height but Hydroxyapatite (HA) alone inadequate in width, usually with lateral deficiency or undercut areas II AR deficient in both height & width and has a HA alone knife edge appearance III AR resorbed to level of the basilar bone, HA alone or mixed with producing concave form on posterior areas of the autogenous cancellous bone mandible and sharp bony ridge form with mobile soft tissue in the maxilla IV Resorption of the basilar bone, producing pencil- HA mixed with autogenous thin, flat mandible or flat maxilla cancellous bone (Mercier,1995)
Modifications: Class II-no wall defect/buccal wall/multiwall defect Class VI- marginal resection /continuity defectAtrophy of the Residual Alveolar Ridge Following Tooth Loss in a Historical Population; Reich, Karoline et al;"Oral Diseases 17, 1 (2010)
Functional effects of edentulism:∆ The maxillomandibular relationship is altered in all spatial dimensions.∆ Progression toward decreased overall lower facial height, leading to thetypical overclosed appearance.∆ Progressive instability of conventional soft tissue
Ideal denture base has following characteristics:a) Adequate bony supportb) Soft tissue coveragec) No undercuts or protuberancesd) No sharp ridgese) Adequate sulcif) Absence of peripheral scar bandsg) no muscle fibres to mobilize prosthesish) No soft tissue folds/hypertrophiesi) No neoplastic lesionsj) Proper maxillomandibular arch relationshipsk) Adequate palatal vault/tuberosity notching
1. History ∆ Chief complaint ∆ Medical history2. Physical examination Soft tissues a) Presence of mass b) Tenderness c) Frena d) Mucous membrane e) Muscle movements f) Relation of oral mucosa to gingiva
Hard tissues a) Undercuts b) Bony prominences c) Sharp ridges d) Ridge form e) Ridge parallelism f) Tuberosity notching Maxillo-mandibular relation Dentition3. Investigations Radiographic a) Gen condition of dentition b) Bone resorption c) Proximity to imp structures d) Maxillo-mandibular relation Lab investigations
Patient selection:∆ General physical status∆ Age∆ Anatomic factors
Preprosthetic proceduresRidge correction• Alveoloplasty• Mylohyoid reduction• Tuberosity reduction• Genial tubercles reduction• Removal of tori• Removal of exostoses• Removal of undercutsRidge extension• vestibuloplastyRidge augmentation• Maxillary• Mandibular
Defined as surgical recontouring of alveolar processHistory: ∆ Willard(1853) –removal of interdental papilla ,permitting edge to edge closure ∆ Beers(1876): radical alveolectomy ∆ De van(1930): trend towards conservatism had begun ∆ Molt(1923):use of study casts in planning alveolectomy ∆ Dean(1936):interseptal alveoloplasty ∆ Obwegesser(1966):modification of dean’s technique ∆ Michael & Barsoum(1976): study on post operative resorption
Principles: 1. Optimal ridge contour 2. Permit early construction of dentures 3. Preservation of alveolar bone 4. Broad alveolar ridges 5. Reduction of irregularities 6. Rounding off sharp ridges 7. Preserve cortical bone as much as possible 8. Defer surgery 4-6 weeks in case of severe periodontitis
Gillies(1956): Mylohyoid ridge should bereduced if found at same or higher levelthan alveolar processRoberts(1977): Reduction of mylohyoidridge & extension of posterior lingualdenture flange into retromylohyoid fossaHowe(1964): Mylohyoid ridge reductionis the most useful single operation
Excess tissue in the region of themaxillary tuberosity may become solarge that it:∆ Impinge upon the mandible duringmastication.∆ Interfere with denture construction,insertion and seatingComplication of tuberosity reduction-expanded tuberosity in proximity tosinus
3 techniques: Removal of tubercle followed byallowing genial muscle to reattachon its own. Removal of tubercle followed byrepositioning of muscle withsutures fastened to chin. Removal of tubercle followed bytransposition of muscle to inferiorborder.
∆ Torus mandibular is an exostosis found on the lingual surface of the mandible opposite the canine and premolars region.∆ Present in 8% of the population, with equal frequency in males and females∆ Usually bilateral, (80% of affected patients), may be single, multiple or lobulated.∆ Etiology: unknown, functional reaction to masticatory forces.
Indications for removal:∆ Tori causing lingual undercuts and interfering with lingual flange extension of the planned prosthesis.∆ When the mucosal covering is ulcerated.∆ Large tori interfering with speech and deglutitionTechniqueComplications
∆ Torus palatinus present itself as an outgrowth in the midline of the palate.∆ Shapes (single dome shaped, spindle shaped, nodular, lobular or multiple).∆ Present in approximately 25% of all females∆ Etiology unknown∆ Composed of cortical bone; may have a cancellous component
Indications for removal: ∆ An extremely large torus filling the palatal vault. ∆ A torus that extend beyond the posterior dam area. ∆ Traumatized mucosa over the torus. ∆ Deep bony undercuts interfering with denture insertion and stability. ∆ Interference with function (speech, deglutition). ∆ Psychological considerations (malignancy phobia).
Indications for Ridge AugmentationProgressive loss of denture stability and retention.Loss of alveolar ridge height, width and decreased vestibular depthand denture bearing area.Considerable basal bone resorption in the mandible, resulting inneurosensory disturbances.Increased susceptibility to fracture of the atrophic jaws.Replacement of necessary supportive bone.Altered interarch relationship
Ridge Augmentation Maxillary augmentation Mandibular augmentation Superior border Inferior border OnlayOnlay bone Interpositio augmentati augmentation grafting: grafting – Alloplastic Sinus Interpositional Visor nal / on (Iliac (Autogenous or AutogenouAutogenou onlay lift procedu / sandwich osteoto grafting sandwich crest, rib allogenic freeze s, allografts / allogenic re bone grafts my grafts graft, dried cadaveric and grafts hydroxyapa mandible) alloplastic tite)
Graft:portion of a tissue or organ that after removal from its origin or donor site ispositioned or inserted at a different place with the objective of reinforcing theexisting tissues &/or correcting a structural defect.
Classification According toAccording to According to embryologic structure source origin Cortical Autograft Membranous Cancellous Allograft Endochondral Cortico- Xenograft cancellous Alloplast
Autogenous Grafts Distant sites Local sites•Rib •Chin•Iliac crest •Body and ramus•Calvarium •ZM buttress•Fibula •Coronoid•Tibia
AUGMENTATION OF SUPERIORBORDER OF MANDIBLE (Davis,1970)Indications:Remaining bone < 10 mmAbility of patient to tolerate procedureDonor considerationsRecipient site
Augmentation of inferior border ofmandibleIndications: ∆ Remaining bone < 10 mm ∆ Risk of pathologic # ∆ Management of malunion or non union of #Donor considerationsRecipient site
ADVANTAGES No vestibule obliteration No dehiscence Less pain Better # stabilization 2o sulculoplasty not required Less bone resorption Indicated for pencil thin ridges Easier to perform skin graft vestibuloplasty DISADVANTAGESScarringPresence of loose submandibular tissueDoes not correct superior irregularities
AUGMENTATION OF MANDIBLE BY PEDICLED FLAPS Horizontal Vertical osteotomy/sandwich osteotomy/visor technique technique
Horizontal osteotomy (Danielson andNemarich)/sandwich techniqueIndication ∆ reasonable amt of bone above mandibular canal ∆ b/l dimension<12-15mm
Vertical osteotomy (Harle,1975)/visorosteotomyIndications ∆ little bone above mandibular canalTechnique
Combined vertical and horizontal osteotomy (Koomen et al)Advantages: ∆ Less risk of # ∆ Better sup & post repositioning of segment ∆ Correction of mild-moderate AP discrepancies ∆ Increase in amt of augmentationTechniqueStoelinga modification
Augmentation with synthetic graft materials:Hydroxyapatite is the prototype of the nonresorbable ceramic bonesubstitutes. It is a calcium phosphate material having physical and chemicalcharacteristic nearly identical to dental enamel and cortical bone.
Advantages:∆ Simple surgical technique suitable as an office procedure.∆ No donor site is required to obtain autogenous bone graft material unless a composite graft is being accomplished.∆ HA is totally biocompatible and nonresorbable∆ Composite grafting can easily be accomplished as in severe class III and IV cases.∆ Vestibular extension after alveolar augmentation is possible after 3 months of primary healing.∆ Local augmentation is possible such as in bridge pontic areas.∆ Metallic implant systems through HA augmented ridges are possible.
Complications: ∆ Dehiscence with extrusion of particles ∆ Abrasion through the mucosa with extrusion of the HA implant ∆ Infection ∆ Abnormal color is noted under the mucosa ∆ Mental nerve neuropathy
The use of particulate bone with membranecoverage allows for both horizontal and verticalaugmentation of the mandible. The membraneis designed to prevent infiltration of theparticulate graft with connective tissue andallow bone to infiltrate into the particulategraft mass rather than connective tissue, withthe formation of sufficient bone.Disadvantage:∆ premature exposure of the membranethrough the mucosa.∆ infectionUsed for ant maxillary combination syndrome
Grafting bone on the superior surface of the residual alveolar cortical boneis accomplished by first gaining access to the cortical bone, placing andsecuring a bone graft to the region to be augmented, and closing the softtissue.Indication: class VAdvantage:1. avoidance of direct damage to the IAN2. ease of placement of the graft3. immediate postoperative vertical augmentation.Disadvantage: incision breakdown over the graft can result in a reduction of the long-term augmentation
Mandibular Tori as a Source for Onlay Bone Graft Augmentation: A Surgical Procedure; Scott D. Ganz JPPA;2007
After alveolar bone osteotomy,distractor device is placed in transport segment, which remains vascularized via periosteumLatencyperiod(5-7 days) Bony segment subjected to tractionDistractionperiod(0.5-1mm/day 1-4 times Activation of tissue growth & regenerationConsolidationperiod(8-12weeks) Formation of distraction callus, matures into bone
Indications: ∆ Moderate-severe alveolar bone defects ∆ Segmental deficiencies ∆ Adjuvant to other grafts ∆ Less b/l width of ridges
Simple, less resorption, include teeth,implants in transport segment, less time
Accurate diagnosis of the problem areas during dentureconstruction and determination of the necessity of surgery isaccomplished by careful evaluation of the informationsystematically obtained from the patient.As conservation is the philosophy of surgical patientmanagement. therefore every attempt should be made to preserveas much as oral structures as possible.Proper knowledge of the available surgical procedures helps inachieving the best results.
1. Preprosthetic oral & maxillofacial surgery-Starshak & Sanders2. Textbook of oral & maxillofacial surgery- Laskin vol II3. Principles of oral & maxillofacial surgery-Peterson4. Textbook of oral & maxillofacial surgery- Fonseca vol 75. Textbook of oral & maxillofacial surgery- Kruger6. Textbook of oral & maxillofacial Surgery – Archer7. Textbook of oral & maxillofacial surgery- Killey And Kay8. Bone grafting in oral implantology: Alfaro
9. Alveolar bone grafting techniques for dental implant preparation- OMFS,Aug 201010. Sugar,Hopkins et al:A sandwich mandibular osteotomy, BJOMS, 1982, 20:16811. Interpositional Osteotomy for Posterior Mandible Ridge Augmentation Michael S. Block, DMD,* Christopher J. Haggerty.JOMS 67:31-39, 2009, Suppl 312. Distraction implants: a new operative technique for alveolar ridge augmentation Alexander Gaggl, Gfinter Schultes, Hans K~ircherJournal of Cranio-Maxillojacial Surge , (1999) 27, 214-22113. Reconstruction of the severely atrophic mandible with iliac crest grafts and endosteal implants: a report of two cases; O’Connell J.E. ,Galvin M, Journal of the Irish Dental Association 2009; 55 (5): 237-241.14. Mandibular Tori as a Source for Onlay Bone Graft Augmentation:A Surgical Procedure Scott D. Ganz,JPPAD