preprosthetic surgery

PREPROSTHETIC SURGERY

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Dr. Sundus Aljazaeri

Types of preprosthetic surgery

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Types of pre-prosthetic surgery can be classified in a number of different ways.

One method is to categorize the surgery as :1.Correction 2.Recontouring3.augmentation of bony or soft tissue.

There are many indications for pre-prosthetic surgery for the patients who are either partially edentulous or completely dentate.

Treatment planning of pre-prosthetic surgery:

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Q- What two challenges must be faced in the prosthodontic rehabilitation of a patient?

A. The restoration of the best masticatory function possible combined with

B. Restoration or improvement of dental and facialesthetics.

What factors should be considered in developing the treatment plan?1. History, 2. physical examination, 3. patient’s chief complaint, 4. expectations, 5. esthetics, 6. functional goals, 7. psychological factors, 8. patient’s surgical risk status, 9. intraoral and extraoral examination.


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Intra-oral examination:1. Amount and contour of the alveolar ridge and basal bone2. Quality of the mucosa covering the denture bearing area3. Depth of the vestibule4. Presence and location of abnormal fibrous and muscle attachments5. Jaw relationship6 Any pathological lesion

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- Inspection, palpation and radiological examination of the

denture bearing area

- Bone ridge contour & form

- Bony undercuts or bony protuberances

- Buccal vestibule

- Palatal vault

- Tuberosity area

- Location of mental foramen & mylohyoid ridge

- Interarch relationship

- Appropriate radiographs –OPG

- Resorption of alveolar ridge

- Muscular & mucosal attachments


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Q- What are the two objectives, goals or premises pre-prosthetic surgery for the edentulous patient?

A. The provision of a comfortable tissue foundation to supportthe denture,

B. Enlargement of the denture bearing area in attemptto provide stability for a denture.


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Soft tissue related surgery

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Labial FrenectomyLingual Frenectomy Mobile soft tissue on the alveolar ridge:

Hyperplastic ridgeEpulis fissuratumPapillomatosis

Denture Granulomas:

Enlarged Tuberosity:Enlarged Retromolar Pad:

Enlargement Of Denture Bearing Areas (Vestibuloplasty)

Labial Frenectomy:

• Labial frenum consists of thin bands offibrous tissue and a few muscle fiberscovered by mucous membrane.

• It usually extends from the upper lip to thecrest of the alveolar ridge. Sometimes it mayextend till the incisive papilla.

• Causes denture instability by interfering withthe peripheral seal

• Can be traumatized –ulcers may form, whichare painful.

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SOFT TISSUE PROCEDURES

ProcedureLAVertical, long, elliptical incision made around the

fibrous bands extending from alveolar ridge to theanterior nasal spine.

Frenum and muscular components are dissected fromthe periosteum deep to vestibular sulcus

Sutures – catgut.Suture length can be Improved by Z plasty or V-Y

procedures.Or by laser

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Labial Frenectomy:

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Lingual Frenectomy

It is necessary when the attachment of the lingual frenum ishigh enough to displace the lower denture during function

Lingual frenum can interfere with speech This condition is called ankyloglossia, where tongue

movements may be restricted.

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Procedure LA / GA Tongue fixed with a stay suture Similar to labial frenectomy. Care taken to avoid injury to papilla of submandibular duct Achieve hemostasis

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Mobile soft tissue on the alveolar ridge:Hyperplastic ridgeEpulis fissuratumPapillomatosis

The mobile and unsupported soft tissues are oftenfound in the anterior maxillary alveolar ridge due toill-fitting dentures.

There may be associated resorption of the bone.

The mobile soft tissues are compressible and hencethe denture becomes very unstable.

Rocking movements of the denture leads to gradualresorption of the underlying bone and may even beexposed in the midline anterior to the nasal spine

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Procedure

Under LA, a linear wedge excision is done.

To facilitate approximation of the wound margins, submucousexcision of the fibrous tissue on either side is done adequately,limiting such dissection to the mobile alveolar soft tissues.

Suturing done.

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Denture Granulomas:• Howe classification:

Class I: granulomas of the masticatory mucosaClass II: granulomas of the lining mucosaClass III: granulomas at the vestibule, obliterating the sulcus

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Usually, surgical defects in class I heal well with minimal • . scarring. In class II lesions, wound should not be closed under tension • Sometimes, wide undermining of the adjacent mucosa may be •

. necessary

. Class III lesions will require epithelial cover •

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Enlarged Tuberosity: Idiopathic fibrous hyperplasia found in relation to the

maxillary posterior teeth may persist even after theremoval of these teeth.

Such enlarged tuberosity may render the denture unstable. It is seen more on the palatal aspect.A three dimensional reduction of such enlarged tuberosity

is required to provide adequate denture space at theposterior region.

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Procedure

Under LA, a wedge of soft tissue from the first molar totuberosity region is excised.

A cushion of tissue from the undersurface of the palatalmucoperioseum is also trimmed so that wound margins can beapproximated without any tension.

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Enlarged Retromolar Pad: This is very similar to the enlarged maxillary tuberosity,

preventing the posterior extension of the denture base. Under LA, an elliptical incision is made around this

hyperplastic region and the excess tissue is excised.Thinning of the flap may be necessary.

Care to be taken not to remove excess tissue on the lingualside to avoid injury to the lingual nerve and vessels.

Suturing done.

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Enlargement Of Denture Bearing Areas (Vestibuloplasty)

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As alveolar ridge resorption takes place, the attachment of mucosa and musclesnear the denture-bearing area exerts a greater influence on the retention andstability of dentures.

In addition, the amount and quality of fixed tissue over the denture-bearingarea may be decreased.

Soft tissue surgery performed to improve denture stability may be carried outalone or may be done after bony augmentation.

In either case the primary goals of soft tissue preprosthetic surgery areto provide an enlarged area of fixed tissue in the primary denture-bearing or implant area and to improve extension in the area of the dentureflanges by removing the dislodging effects of muscle attachments in thedenture-bearing or vestibular areas.

Enlargement Of Denture Bearing Areas (Vestibuloplasty) The anterior part of the body of the mandible is the

sight most frequently involved: the labial sulcus is virtually obliterated and the mentalis muscle attachment appear to migrate to the crest of the residual ridge.

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Exposed tissue covered b y:1. Tongue flap2. Skin graft3. By the denture4. HemCon Dressing

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Current HemCon Product Portfolio

HemConBandage

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ChitoFlex

Ridge corrective procedures

They are mainly aimed at altering, improving or evenreplacing the tissues of the denture-bearing area.

When they are done during dental extractions or beforeinserting the denture for the first-time, they are calledprimary procedures.

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Alveoloplasty

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RECONTOURING OF ALVEOLAR RIDGES

1. Alveolar compression2. Simple Alveoloplasty Associated with Removal of Multiple Teeth3. Intraseptal Alveoloplasty4. Knife Edged Ridge5. Reduction Buccal Exostosis and Excessive Undercuts6. Maxillary Tuberosity Reduction (Hard Tissue)7. Lateral Palatal Exostosis8. Mylohyoid Ridge Reduction9. Genial Tubercle Reduction

TORI REMOVAL1. Maxillary Tori2. Mandibular Tori

1) Alveolar compressionThe simplest form of alveoloplasty consists of the

compression of the lateral walls of the extraction. socket after simple tooth emovalIn many cases of single tooth extraction, digital

compression of the extraction site adequately contours the underlying bone, provided no gross irregularities of

.bone contour are found in the area after extractio

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2) AlveoloplastyA. Simple Alveoloplasty

Indications:∆ Reduction of buccal/labial plate∆ Extraction of single/multiple teeth∆ Over erupted teeth

Technique:Depending on the degree of irregularity of the alveolar ridge area,recontouring can be accomplishedwith a rongeur, a bone file, or abone bur in a handpiece, alone or in combination

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B. Labial & Buccal Cortical Alveoloplasty

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3) Intraseptal AlveoloplastyA. Dean’s Intraseptal /Intercortical/Crush Technique

An alternative to the removal of alveolar ridge irregularities by the simple

alveoloplasty technique is the use of an intraseptal alveoloplasty, or dean’s

technique, involving the removal of intraseptal bone and the repositioning of

the labial cortical bone, rather than removal of excessive or irregular areas of

the labial cortex.

This technique is best used in an area where the ridge is of relatively regularcontour and adequate height but presents an undercut to the depth of thelabial vestibule because of the configuration of the alveolar ridge.

The technique can be accomplished at the time of tooth removal or in the earlyinitial postoperative healing period. 31

Indications:

∆ immediate dentures∆ quadrant extraction

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B. Obwegesser’s Technique

After the extraction of the teeth (A), the interseptal bone removed (B), two vertical cut labially and palatally done on both side(C), then used a disc bur to cut both buccal and palatal plate (D), Fractured both plate (E), Crush both plate together more palatally (F), then suture (G). Indicationpremaxillary protrusion

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4. Knife Edged Ridge Reduction

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Extreme resorption resultsin sharp, pointed ridge thatcuts into mucoperiosteumon pressure application.

Pain occurs on wearingdentures.

5. Reduction Buccal Exostosis and Excessive Undercuts

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Excessive bony protuberances and resulting undercut areasare more common in the maxilla than in the mandible.

A local anaesthetic should be infiltrated around the arearequiring bony reduction. For mandibular buccal exostosis,inferior alveolar blocks may also be required to anesthetizebony areas.

A crestal incision extends 1 to 1.5 cm beyond each end ofthe area requiring contour, and a full thicknessmucoperiosteal flap is reflected to expose the areas of bonyexostosis. If adequate exposure cannot be obtained,vertical-releasing incisions are necessary to provide accessand prevent trauma to the soft tissue flap.

If the areas of irregularity are small, recontouring with abone file may be all that is required; larger areas maynecessitate use of a rongeur or rotary instrument.

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6. Maxillary Tuberosity Reduction (Hard Tissue)

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Horizontal or vertical excess of the maxillary tuberosity area may bea result of excess bone, an increase in the thickness of soft tissueoverlying the bone, or both.

7. Lateral Palatal Exostosis

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The lateral aspect of the palatal vault may be irregular because of the presence oflateral palatal exostosis.

This presents problems in denture construction because of the undercut created by theexostosis and the narrowing of the palatal vault.

Occasionally, these exostoses are large enough that the mucosa covering the areabecomes ulcerated.

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8. Mylohyoid Ridge Reduction

One of the more common areas interfering with proper dentureconstruction in the mandible is the mylohyoid ridge area. in additionto the actual bony ridge, with its easily damaged thin covering ofmucosa, the muscular attachment to this area often is responsiblefor dislodging the denture. when this ridge is extremely sharp,denture pressure may produce significant pain in this area.

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Obwegesser modification

9. Genial Tubercle Reduction

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As the mandible begins to undergo resorption, the area of the attachment ofthe genioglossus muscle in the anterior portion of the mandible may becomeincreasingly prominent. In some cases, the tubercle may actually function as ashelf against which the denture can be constructed, but it usually requiresreduction to construct the prosthesis properly. Before a decision to removethis prominence is made, consideration should be given to possibleaugmentation of the anterior portion of the mandible rather thanreduction of the genial tubercle.

1. maxillary tori

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Maxillary tori consist of bony exostosis formation in the area of thepalate.

The origin of maxillary tori is unclear. Tori are found in 20%of the female population, which is approximately twice the preva-lence rate in males.

Tori may have multiple shapes and configure tions, ranging from a single smooth elevation to a multiloculated pedunculated bony mass. Tori present few problems when the maxillary dentition is present and only occasionally interfere with speech or become ulcerated from frequent trauma to the palate.

However, when the loss of teeth necessitates full or partial denture construction, tori often interfere with proper design and function of the prosthesis.Tori are usually removed to avoid undercuts and to make possible a border seal beyond them against the floor of the mouth.

TORI REMOVAL

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The indications for the removal of maxillary tori are as follows:

An extremely large torus that prevents the formation of anadequately extended and stable maxillary denture.

An under cut torus that traps food debris, causing a chronicinflammatory condition.

A torus that extends past the junction of the hard and softpalates and prevents an adequate posterior palatal seal.

One that causes the patient concern (because of a cancerphobia)

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2. Mandibular tori

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Mandibular tori are bony protuberances on the lingual aspect of the mandible that usually occur in the premolar area.

The origins of this bony exostosis are uncertain, and the growths may slowlyincrease in size. Occasionally, extremely large tori interfere with normal speech or tongue function during eating, but these tori rarely require removal when teeth are present.

After the removal of lower teeth and before the construction of partial or complete dentures, it may be necessary to remove mandibular tori to facilitate denture construction

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Pressure on the mental foramen. If bone resorption in the mandible has been extreme, the mental

foramen may open near or directly at the crest of the residual bony process. This causes the margins of the mental foramen to extend and have very sharp edges 2 to 3 mm higher than the surrounding mandibular bone. Pressure from the denture against the mental nerve exiting the foramen and over this sharp bony edge will cause pain.

The most suitable way of managing this is to alter the denture so pressure does not exist. However, in rare instances it may be necessary to trim the bone to relieve the mental nerve of pres-sure.

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Ridge Augmentation indications for ridge augmentation.1 progressive loss of denture stability and retention.

2. loss of alveolar ridge height, width and decreasedvestibular depth and denture bearing area.

.3 considerable basal bone resorption in the mandible,resulting in neurosensory disturbances.

.4increased susceptibility to fracture of the atrophic jaws.

.5replacement of necessary supportive bone.

.6altered interarch relationship 49

Ridge Augmentation

Maxillary augmentation

Onlay bone grafting –

Autogenous/ allogenic

grafts

Alloplasticonlay grafting

Interpositional /

sandwich grafts

Sinus lift procedur

e

Mandibular augmentation

Superior border

augmentation (Iliac crest, rib

graft, hydroxyapat

ite)

Inferior border augmentation

(Autogenous or allogenic freeze dried cadaveric

mandible)

Interpositional/ sandwich bone grafts

Visor osteoto

my

Onlaygrafting:

Autogenous, allograft and

alloplastic

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Materials used for augmentation

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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

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Augmentation with synthetic graftmaterials:

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

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Augmentation using Ti Mesh

the use of particulate bone with membranecoverage allows for both horizontal and verticalaugmentation of the mandible. the membrane isdesigned to prevent infiltration of theparticulate graft with connective tissue andallow bone to infiltrate into the particulate graftmass rather than connective tissue, with theformation of sufficient bone.

disadvantage:

∆ premature exposure of the membranethrough the mucosa.

∆ infection

used for ant maxillary combination syndrome

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REPLACING TOOTH ROOTS BY OSSEOINTEGRATED DENTAL IMPLANTS.

Complete dentures are not the only method available for treating edentulous patients. In implant technique, a number of cylindrically shaped screws, made of specific materials are buried inside the

selected host bone sites

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preprosthetic surgery

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