PRE PROSTHETIC SURGERY- HARD TISSUES

PRE PROSTHETIC SURGERY- HARD TISSUES

ContentsIntroductionObjectives Patient evaluation and Treatment planning Evaluation of the supporting bony tissues Recontouring of alveolar ridges Maxillary tuberiosity reduction Buccal exostosis and excessive undercuts Lateral palatal exostosis Mylohyoid ridge reductionTori removalBone augmentation

IntroductionPreprosthetic surgery refers to the surgical procedures that can modify the oral anatomy to facilitate the retention of conventional dentures.

The ultimate goal of preprosthetic surgery is to prepare the mouth to receive dental prosthesis by redesigning and smoothing bony edges or areas and removing excess of flabby soft tissues

ObjectivesNo evidence of intraoral and extraoral pathological conditions. Proper inter arch jaw relationship Alveolar processes that are as large as possible and of the proper configuration. No bony or soft tissue protuberances or undercuts Adequate palatal vault form Proper posterior tuberosity notching Adequate attached keratinized mucosa and adequate vestibular depth. Protection of the neurovascular bundle

Preprosthetic procedures

Ridge correctionAlveoloplastyMaxillary tuberosity reductionRemoval of exostosisRemoval of undercutsLateral palatal exostosisMylohyoid reductionGenial tubercles reductionRemoval of tori Ridge augmentationMaxillaryMandibular

Patient evaluation and treatment planningPreprosthetic surgical treatment must begin with a proper case history and physical examinationSpecial attention should be given to systemic diseases that may be responsible for the severe degree of bone resorption.Esthetic and functional goals of the patient must be assessed carefully.Long term maintenance of the underlying tissues as well as prosthetic appliances should be kept in mind.

Recontouring of alveolar bone Simple alveoloplastyIntraseptal or Deans alveoloplasty

ALVEOLOPLASTYDefined as surgical recontouring of alveolar process

IndicationsPatients with prominent and dense alveolarbone undergoing extractionPrior to construction of an immediate denture

The simplest form of alveoloplasty consists of compression of the lateral walls of the extraction socket after simple tooth removal

Bony areas requiring recontouring should be exposed using an envelop type of flap.A mucoperiosteal incision along the crest of the ridge with adequate A-P extension is givenAdequate visualization and access to the alveolar ridge obtainedVertical incisions given if necessary Excessive flap reflection may result in devitalized areas of bone which may resorb rapidly after surgeryRecontouring can be accomplished with Rongeur Bone file Bone bur in handpiece

Copious saline irrigation should be done throughout the recontouring procedure to avoid overheating and bone necrosisAfter this the edges of the flap are trimmed and then sutured with continuous or noncontinuous sutures.

RONGEURBONE BURBONE FILE

DEANS INTRASEPTAL ALVEOLOPLASTYThis technique is best used in an area where the ridge is of relative regular contour and adequate height but presents an undercut to the depth of the labial vestibule. Performed during the time of extraction

Advantages :Labial prominence is reduced without reducing the height of the ridgeThe periosteal attachment to the bone can be maintained hereby reducing bone resorptionMuscle attachments are left undisturbedDisadvantage : Decrease in ridge thickness

MAXILLARY TUBEROSITY REDUCTIONExcess 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

Lateral palatal exostosisPresents problems in denture construction because of the undercut created by the exostosis and narrowing of the palatal vault

Technique :Local anesthetic solution in the area of the greater palatine foramen Crestal incision made from the posterior aspect of the tuberosity extending to the exostosis Reflection of the mucoperiostium Removal of excess bony projection by a bone file Saline irrigationSuturing

Mylohyoid ridge reductionLinear incision is made over the crest of the ridge in the posterior aspect of the mandibleFull thickness mucoperiosteal flap is elevated to expose the musclesBone file is used to remove the sharp prominance of the mylohyoid ridge

Genial tubercle reductionReduction required to construct the prosthesis properlyIf augmentation is to be carried out, tubercle left to add support to the graft

Tori removalIn the patient requiring complete or partial conventional prosthetic restoration, tori maybe a significant obstruction to insertion or interfere with the overall comfort, fit, and function of the planned prosthesis.In the maxilla,bilateral greater palatine and incisive blocks are given.

A linear midline incision with posterior and anterior vertical releases or a U-shaped incision in the palate followed by a subperiosteal dissection is used to expose the defect. Rotary instrumentation with a round acrylic bur may be used for small areas; however, for large tori, the treatment of choice is sectioning with a cross-cut fissure bur. Once sectioned into several pieces, the torus is easily removed with an osteotome

Closure is performed with a resorbable suture. Presurgical fabrication of a thermoplastic stent, made from dental models with the defect removed, in combination with a tissue conditioner helps to eliminate resulting dead space, increase patient comfort. Complications :- Postoperative hematoma, Perforation of the floor of the nose Necrosis of the flap

MANDIBULAR TORI

Bilateral lingual and inferior alveolar anesthesia is givenIncision extending from 1 to 1.5cms beyond each tori is givenAlways leave behind a band of tissue attached to the midline between the anterior extent of the 2 incisions.When the torus has a small pedunculated base, a mallet and an osteotome is used to cleave the tori from the medial aspect of the mandibleThe direction of the initial bur is parallel to the medial aspect of the mandible to prevent fracture of the lingual or inferior cortex

A bone file is then used to smoothen the lingual cortexPalpation is done to check for proper contour and presence of any undercutsContinuous suturing is done and gauze packs are placed and retained for the next 12 hrsThe direction of the initial bur is parallel to the medial aspect of the mandible to prevent fracture of the lingual or inferior cortexA bone file is then used to smoothen the lingual cortexPalpation is done to check for proper contour and presence of any undercutsContinuous suturing is done and gauze packs are placed and retained for the next 12 hrs

Mandibular augmentationAugmentation grafting adds strength to an extremely deficient mandible and improves the height of contour of the available bone for implant placement on the denture bearing areas.The sources of graft material include autogenous or alloplastic bone and alloplastic materials

Superior border augmentation

Thoma & Holland technique:

Corticocalcellous iliac crest blocks are contoured to adapt to the configuration of the mandible.Then fixated with screws and miniplates

Hydroxyapatite augmentation

OsteopromotionA membrane is used to cover an area where bone regeneration is necessaryBy placing a membrane over the bone graft, faster growing fibroblasts and epithelial cells are walled off allowing the bone to grow in a relatively protected environment.Currently, expanded polytetrafluoroethylene is used as a membrane.

Onlay bone graft

Sinus liftExtension of the maxillary sinus into the alveolar ridge may prevent placement of implants in the posterior maxillary area because of insufficient bony support.A sinus lift procedure is a bony augmentation procedure that places graft material inside the sinus and augments the bony support in the alveolar ridge area.The graft is allowed to heal for 3 to 6 months after which the first stage of implant placement can begin.