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