pre prosthetic surgery (2)
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PRE PROSTHETIC SURGERY(Hard tissue)
- Dr. Dona Bhattacharya
Contents1. Introduction2. Objectives3. Alveolar atrophy 4. Diagnosis & treatment planning5. Ridge correction procedures
a) Alveoloplastyb) Mylohyoid reductionc) Tuberosity reductiond) Genial tubercles reduction
e) Removal of torif) Removal of exostosesg) Removal of undercuts
6. Ridge augmentation7. Conclusion8. References
Introduction ∆ Preprosthetic surgery refers to the surgical procedures that can modify the oral anatomy to facilitate the retention of conventional dentures.
∆ According to the Glossary of Prosthodontic Terms (7), preprosthetic surgery is defined as surgical procedures designed to facilitate fabrication or to improve the prognosis of prosthodontic care.
∆ According to Bruce Donoff, preprosthetic surgery is that part of the oral and maxillofacial surgery designed to establish the best hard and soft tissue bases for prosthetic appliances.
Objectives
∆ Elimination of disease
∆ Conservation of oral structures
∆ Provide residual tissue to withstand masticatory forces
∆ Maintain function
∆ Esthetics
Alveolar Atrophy∆ The term alveolar atrophy refers to the regression of the teeth-supporting, crescent-shaped osseous part of the upper and lower jaw.
Causes:
∆ Periodontal diseases∆ Trauma∆ Pt factors (age, gender, skeletal morphology)∆ Endocrine & metabolic disorders (hyperparathyrodism,Ca defeciency)∆ Dietary considerations∆ Mechanical factors (extractions,removable denture wearers, combination syndrome)
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, Acta Stomat Croat 2002; 261-265)
Alveolar Atrophy
(Mercier,1995)
Class Characteristics Treatment
I Alveolar ridge (AR) adequate in height but inadequate in width, usually with lateral deficiency or undercut areas
Hydroxyapatite (HA) alone
II AR deficient in both height & width and has a knife edge appearance
HA alone
III AR resorbed to level of the basilar bone, producing concave form on posterior areas of the mandible and sharp bony ridge form with mobile soft tissue in the maxilla
HA alone or mixed with autogenous cancellous bone
IV Resorption of the basilar bone, producing pencil-thin, flat mandible or flat maxilla
HA mixed with autogenous cancellous bone
Atrophy of the Residual Alveolar Ridge Following Tooth Loss in a Historical Population; Reich, Karoline et al;"Oral Diseases 17, 1 (2010)
Modifications:
Class II-no wall defect/buccal wall/multiwall defect
Class VI-marginal resection /continuity defect
Functional effects of edentulism:
∆ The maxillomandibular relationship is altered in all spatial dimensions.
∆ Progression toward decreased overall lower facial height, leading to the typical 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
Diagnosis & Treatment Planning
1. History∆ Chief complaint∆ Medical history
2. Physical examination Soft tissues
a) Presence of massb) Tendernessc) Frenad) Mucous membranee) Muscle movementsf) Relation of oral mucosa to gingiva
Hard tissuesa) Undercutsb) Bony prominencesc) Sharp ridgesd) Ridge forme) Ridge parallelismf) Tuberosity notching
Maxillo-mandibular relation Dentition
3. Investigations Radiographic
a) Gen condition of dentitionb) Bone resorptionc) Proximity to imp structuresd) Maxillo-mandibular relation
Lab investigations
Patient selection:
∆ General physical status∆ Age∆ Anatomic factors
Preprosthetic procedures
Ridge correction• Alveoloplasty• Mylohyoid reduction• Tuberosity reduction• Genial tubercles reduction• Removal of tori• Removal of exostoses• Removal of undercuts
Ridge extension• vestibuloplasty
Ridge augmentation• Maxillary• Mandibular
Alveoloplasty Defined as surgical recontouring of alveolar process
History:
∆ 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 contour2. Permit early construction of dentures3. Preservation of alveolar bone4. Broad alveolar ridges5. Reduction of irregularities6. Rounding off sharp ridges7. Preserve cortical bone as much as possible8. Defer surgery 4-6 weeks in case of severe
periodontitis
Alveoloplasty Types
Alveolar compressio
n
Simple alveoloplas
ty
Labial & buccal cortical
Dean’s intraseptal
Obwegesser’s
technique
1) Alveolar compression
∆ Easiest & quickest method∆ Involves compression of cortical plates with fingers∆ Reduction in socket width
2) Simple Alveoloplasty
Indications:∆ Reduction of buccal/labial plate∆ Extraction of single/multiple teeth
Technique:∆ Single tooth extraction∆ Multiple teeth extraction∆ Over erupted teeth
3) Labial & Buccal CorticalAlveoloplasty
4) Dean’s Intraseptal /Intercortical/Crush TechniquePrinciples:
a) Reduction of labial/alveolar prominencesb) Muscle attachments are undisturbedc) Intact periosteumd) Preserve cortical bonee) Less post-op resorption
Indications:
∆ immediate dentures∆ quadrant extraction
Technique:
Mac Kay’s modification(1964)
5) Obwegesser’s Technique
1966
Indication
-premaxillary protrusion
Technique
Advantages
Knife Edged Ridge Reduction
Extreme resorption results in sharp, pointed ridge that cuts into mucoperiosteum on pressure application.
Pain occurs on wearing dentures.
Technique
Mylohyoid Ridge Reduction
Gillies(1956): Mylohyoid ridge should be reduced if found at same or higher level than alveolar process
Roberts(1977): Reduction of mylohyoid ridge & extension of posterior lingual denture flange into retromylohyoid fossa
Howe(1964): Mylohyoid ridge reduction is the most useful single operation
Technique (Trauner)
Obwegesser modification
Maxillary Tuberosity Reduction
Excess tissue in the region of the maxillary tuberosity may become so large that it:
∆ Impinge upon the mandible during mastication.∆ Interfere with denture construction, insertion and seating
Complication of tuberosity reduction-expanded tuberosity in proximity to sinus
Genial Tubercle Reduction
3 techniques:
Removal of tubercle followed by allowing genial muscle to reattach on its own.
Removal of tubercle followed by repositioning of muscle with sutures fastened to chin.
Removal of tubercle followed by transposition of muscle to inferior border.
Mandibular Tori Removal∆ 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 deglutition
Technique
Complications
Palatal Tori Removal
∆ 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).
Technique
Position: head tilted backward
Complications:
∆ Haemorrhage∆ Hematoma formation.∆ Nasal or antral perforation.∆ Sloughing and necrosis of palatal tissues.∆ Fracture of palatine bone.
Palatal Exostosis
Found in maxillary molar region.
Preservation of vascular supply: main concern during surgery
Buccal Exostosis
Labial Undercuts
Caused by resorption in apical areas.
Treatment:∆ Excision∆ Filling of undercut
Technique
Ridge Augmentation
Ridge Augmentation
Indications for Ridge Augmentation
Progressive loss of denture stability and retention.
Loss of alveolar ridge height, width and decreased vestibular depth and denture bearing area.
Considerable basal bone resorption in the mandible, resulting in neurosensory disturbances.
Increased susceptibility to fracture of the atrophic jaws.
Replacement of necessary supportive bone.
Altered interarch relationship
Ridge Augmentation
Maxillary augmentation
Onlay bone
grafting – Autogeno
us / allogenic
grafts
Alloplastic onlay
grafting
Interpositional /
sandwich grafts
Sinus lift proced
ure
Mandibular augmentationSuperior
border augmentation (Iliac crest,
rib graft,
hydroxyapatit
e)
Inferior border augmentation (Autogenous or allogen
ic freeze dried
cadaveric
mandible)
Interpositional
/ sandwi
ch bone grafts
Visor osteoto
my
Onlay graftin
g: Autogenous,
allograft and
alloplastic
Materials used for augmentation
Graft: portion of a tissue or organ that after removal from its origin or donor site is positioned or inserted at a different place with the objective of reinforcing the existing tissues &/or correcting a structural defect.
Classification
According to structure
Cortical
Cancellous
Cortico-cancellous
According to source
Autograft
Allograft
Xenograft
Alloplast
According to embryologic origin
Membranous
Endochondral
Autogenous Grafts
Distant sites•Rib•Iliac crest•Calvarium•Fibula•Tibia
Local sites•Chin•Body and ramus•ZM buttress•Coronoid
Mandibular AugmentationAUGMENTATION OF SUPERIOR BORDER OF MANDIBLE (Davis, 1970)
Indications:Remaining bone < 10 mmAbility of patient to tolerate procedure
Donor considerations
Recipient site
Kerfing of rib graft
Mandibular Augmentation
Augmentation of inferior border of mandible
Indications:∆ Remaining bone < 10 mm∆ Risk of pathologic #∆ Management of malunion or non
union of #
Donor considerations
Recipient site
DISADVANTAGES Scarring
Presence of loose submandibular
tissue Does not correct
superior irregularities
Mandibular Augmentation
AUGMENTATION OF MANDIBLE BY PEDICLED FLAPS
Horizontal osteotomy/sandwich technique
Vertical osteotomy/visor technique
Horizontal osteotomy (Danielson and Nemarich)/sandwich technique
Indication∆ reasonable amt of bone above
mandibular canal∆ b/l dimension<12-15mm
Mandibular Augmentation
Technique
Donor siteRecipient site
Lekkas modification
Vertical osteotomy (Harle,1975)/visor osteotomy
Indications∆ little bone above mandibular
canal
Technique
Mandibular Augmentation
Mandibular Augmentation
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 augmentation
Technique
Stoelinga modification
Maxillary Augmentation
Bell & mc bride(1977)
Augmentation with synthetic graft materials:
Hydroxyapatite is the prototype of the nonresorbable ceramic bone substitutes. It is a calcium phosphate material having physical and chemical characteristic nearly identical to dental enamel and cortical bone.
Ridge Augmentation
Technique
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
Augmentation using Ti Mesh
The use of particulate bone with membrane coverage allows for both horizontal and vertical augmentation of the mandible. The membrane is designed to prevent infiltration of the particulate graft with connective tissue and allow bone to infiltrate into the particulate graft mass rather than connective tissue, with the formation of sufficient bone.
Disadvantage:
∆ premature exposure of the membrane through the mucosa.∆ infection
Used for ant maxillary combination syndrome
Onlay graft augmentation
Grafting bone on the superior surface of the residual alveolar cortical bone is accomplished by first gaining access to the cortical bone, placing and securing a bone graft to the region to be augmented, and closing the soft tissue.
Indication: class V
Advantage:
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:
Mandibular Tori as a Source for Onlay Bone Graft Augmentation: A Surgical Procedure; Scott D. Ganz JPPA;2007
Vertical augmentation with distraction
osteogenesis
After alveolar bone osteotomy,distractor device is placed in transport segment, which remains vascularized via periosteum
Bony segment subjected to traction
Activation of tissue growth & regeneration
Formation of distraction callus, matures into bone
Latency period(5-7 days)Distraction period(0.5-1mm/day 1-4 times
Consolidation period(8-12 weeks)
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
ConclusionAccurate diagnosis of the problem areas during denture construction and determination of the necessity of surgery is accomplished by careful evaluation of the information systematically obtained from the patient.As conservation is the philosophy of surgical patient management. therefore every attempt should be made to preserve as much as oral structures as possible.Proper knowledge of the available surgical procedures helps in achieving the best results.
References1. 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
References9. 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 3
12. Distraction implants: a new operative technique for alveolar ridge augmentation Alexander Gaggl, Gfinter Schultes, Hans K~ircherJournal of Cranio-Maxilloj'acial Surge , (1999) 27, 214-221
13. 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
Thank You