L1 Preprosthetic Surgery - Hard Tissue PDF

L1- 5th Y Preprosthetic Surgery Dr Amera Alkaisi 19-8-2024 Hard Tissue Preprosthetic surgery Are group of soft and hard tissue procedures. The objective of preprosthetic surgery To create proper supporting structures for subse...

L1- 5th Y Preprosthetic Surgery Dr Amera Alkaisi 19-8-2024 Hard Tissue Preprosthetic surgery Are group of soft and hard tissue procedures. The objective of preprosthetic surgery To create proper supporting structures for subsequent placement of prosthetic appliances. Preprosthetic surgical treatment must begin with ▪ History Thorough history of general health is important and systemic conditions that may directly affect bone healing must be determined. ▪ Physical examination of the patient General o Specific attention should also be given to possible systemic diseases that may be responsible for the severe degree of bone resorption. o Laboratory tests such as serum levels of calcium, phosphate, parathyroid hormone, and alkaline phosphatase may be useful to determine the potential metabolic problems that may affect bone resorption. o Intraoral and extraoral examination of the patient should include an assessment of 1. Hard tissue ▪ The existing occlusal relationships if any remain ▪ The ridge form and contour or any gross ridge irregularities ▪ Presence of tori, and buccal exostosis ▪ The jaw relationships ▪ The presence of soft tissue or bony pathologic condition. ▪ Palpation of all areas of the maxilla and mandible, including the primary denture- bearing area and vestibular area, is necessary ▪ Palpate between the external oblique line and mylohyoid ridge. 1  ▪ Any bony undercuts or gross bony protuberances that block the path of denture insertion. Soft tissue o The quality of overlying soft tissue, the amount of keratinized tissue and its attachment to the underlying bone in the denture-bearing area o Check for the presence of hypermobile fibrous tissue o Location of muscle attachments, muscular and mucosal attachments near the crest of the ridge should be palpated o The vestibular depth o The vestibular areas should be free of inflammatory changes such as scarred or ulcerated areas caused by denture pressure or hyperplastic tissue resulting from an ill- fitting denture. o Check frena that approximate the crest of the alveolar ridge and are often responsible for the loss of peripheral seal of the denture during speech and mastication. o The lingual aspect of the mandible should be inspected to determine the level of attachment of the mylohyoid muscle in relation to the crest of the mandibular ridge and the attachment of the genioglossus muscle in the anterior mandible. o The linguovestibular depth should be evaluated with the tongue in several positions because movement of the tongue accompanied by elevation of the mylohyoid and genioglossus muscles is a common cause of movement and displacement of the lower denture. ▪ Radiological examination 1. Lateral and posteroanterior cephalometric radiographs with the jaws in proper postural positionmay be helpful in confirming a skeletal discrepancy, ridge relationships and interarch distance. 2. Panoramic radiographic techniques provide an excellent overview assessment of underlying bony structure and pathologic conditions. 3. Radiographs should disclose bony pathologic lesions, impacted teeth or portions of remaining roots, the bony pattern of the alveolar ridge, and pneumatization of the maxillary sinus 4. Computed tomography (CT) scans may provide further information. CT scans are particularly helpful in evaluating the cross-sectional anatomy of the maxilla, including ridge form and sinus anatomy, the location of the inferior alveolar nerve and mental foramina can be evaluated more precise Treatment Planning A treatment plan addressing the patient’s identified oral problems should be formulated before any surgical intervention. o The most appropriate treatment plan should consider ridge height, width, and contour. several other factors should also be considered: o In an older patient in whom moderate bony resorption has taken place, soft tissue surgery alone may be sufficient for improved prosthesis function. In an extremely young 2  patient who has undergone the same degree of atrophy, bony augmentation procedures may be indicated. o The role of implants may alter the need for surgical modification of bone or soft tissue. o When there appears to be redundant or loose soft tissue over the alveolar ridge area, the most appropriate long-term treatment plan may involve grafting bone to improve the contour of the alveolar ridge or support endosteal implants. o If bony augmentation is indicated, maximum augmentation frequently depends on availability of adjacent soft tissue to provide tension-free coverage of the graft. o Soft tissue surgery should be delayed until hard tissue grafting and appropriate healing have occurred. Bony reconstruction ❖ Recontouring of alveolar ridge Irregularities of the alveolar bone found at the time of tooth extraction or after a period of initial healing require recontouring before final prosthetic construction. preparation of ridges for removable prostheses. 1. Simple Alveoloplasty Associated with Removal of Multiple Teeth ▪ The simplest form of alveoloplasty. ▪ Consists of the compression of the lateral walls of the extraction socket after simple tooth removal. ▪ In 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 extraction. ▪ When multiple irregularities exist, more extensive recontouring often is necessary. ▪ A conservative alveoloplasty in combination with multiple extractions is carried out after all of the teeth in the arch have been removed. ▪ Alveolar ridge recontouring at the time of tooth extraction or after a period of healing, the technique is essentially the same. Surgical procedure Incision and flap ▪ Incision along the crest of the ridge is made with adequate extension anteroposterior to expose the bony area requiring recontouring, using an envelope flap. approximately 1 cm mesial and distal to the site is adequate. ▪ A mucoperiosteal flap is reflected to allow adequate visualization and access to the alveolar ridge and protect soft tissue adjacent to this area during the procedure. ▪ If adequate exposure is not possible, small vertical-releasing incisions may be necessary, to prevent the possibility of tear in the edges of a flap, although releasing incisions often create more discomfort during the healing period. ▪ The mucoperiosteum should be reflected only to the extent that adequate exposure to the area of bony irregularity can be achieved. Excessive flap reflection may result in 3  devitalized areas of bone, which will resorb more rapidly after surgery, and a diminished soft tissue adaptation to the alveolar ridge area. 9 Recontouring the ridge Depending on the degree of irregularity of the alveolar ridge area, recontouring can be accomplished with a rongeur, a bone file, mallet and osteotome or a bone bur in a handpiece, alone or in combination. Copious saline irrigation should be used throughout the recontouring procedure to avoid overheating (temperature less than 47 C° is safe) and bone necrosis. Suturing ▪ The flap should be reapproximated by digital pressure and the ridge palpated to ensure that all irregularities have been removed. ▪ After copious irrigation to ensure removal of debris, the tissue margins can be reapproximated with interrupted or continuous sutures. ▪ Resorbable sutures are usually used to approximate tissue and add tensile strength across the wound margins. ▪ The resorbable material is broken down by salivary proteolytic enzymes or hydrolysis over several days to weeks, eliminating the need for removal. 4  ▪ If an extensive incision has been made, continuous suturing tends to be less annoying to the patient and provides for easier postoperative hygiene because of the elimination of knots and loose suture ends along the incision line. ▪ The initial soft tissue redundancy (loose and sagging) created with reduction of the bony irregularities often shrinks and readapts over the alveolus, allowing preservation of attached gingiva. Sharp knife-edge ridge ▪ If exists in the mandible, the sharp superior portion of the alveolus can be removed in a manner similar to simple alveoloplasty. ▪ After local anesthesia is obtained, a crestal incision is made, extending along the alveolar ridge, approximately 1 cm beyond either end of the area requiring recontouring. ▪ After minimal reflection of the mucoperiosteum, a rongeur can be used to remove the major portion of the sharp area of the superior aspect of the mandible. ▪ A bone file is used to smooth the superior aspect of the mandible. ▪ After copious irrigation, this area is closed with continuous or interrupted sutures. ▪ Before removal of any bone, strong consideration should be given to reconstruction of proper ridge form using grafting procedures. 5  2. Intaseptal Alveoloplasty (Dean’s technique) Is an alternative to simple alveoloplasty technique ▪ The removal of intraseptal bone and the repositioning of the labial cortical bone ▪ It is best used in an area where the ridge is of relatively regular contour and adequate height but presents an undercut to the depth of the labial vestibule because of the configuration of the alveolar ridge. ▪ The technique can be accomplished at the time of tooth removal or in the early initial postoperative healing period. Procedure ▪ After exposure of the crest of the alveolar ridge by reflection of the mucoperiosteum, a small rongeur can be used to remove the intraseptal portion of the alveolar bone. ▪ Digital pressure should be sufficient to fracture the labiocortical plate of the alveolar ridge inward to approximate the palatal plate area more closely. ▪ Occasionally, small vertical cuts at either end of the labiocortical plate facilitate repositioning of the fractured segment. By using a bur or osteotome inserted through the distal extraction area, the labial cortex is scored without perforation of the labial mucosa. ▪ Digital pressure on the labial aspect of the ridge is necessary to determine when the bony cut is complete and to ensure that the mucosa is not damaged. ▪ After positioning of the labiocortical plate, any slight areas of bony irregularity can be contoured with a bone file and the alveolar mucosa can be reapproximated with interrupted or continuous suture techniques. ▪ A splint or an immediate denture lined with a soft lining material can then be inserted to maintain the bony position until initial healing has taken place. Advantages of this technique 1. The labial prominence of the alveolar ridge can be reduced without significantly reducing the height of the ridge in this area. 2. The periosteal attachment to the underlying bone can also be maintained thereby reducing postoperative bone resorption and remodeling. 3. The muscle attachments to the area of the alveolar ridge can be left undisturbed in this type of procedure. 4. The main disadvantage of this technique is the decrease in ridge thickness, it may prevent placement of implants in the future. 6  ❖ Maxillary Tuberosity Reduction (Hard Tissue) 1. Horizontal or vertical excess of the maxillary tuberosity area may be a result of excess bone, an increase in the thickness of soft tissue overlying the bone, or both. 2. A preoperative radiograph or selective probing with a local anesthetic needle are often useful to determine the extent to which bone and soft tissue contribute to this excess and to locate the floor of the maxillary sinus. 3. Recontouring of the maxillary tuberosity area may be necessary to remove bony ridge irregularities or to create adequate inter arch space, 4. Intermaxillary distance (space): it should be at least 1 cm. A dental mirror passing freely between the tuberosity and retromolar tissue suggests adequate vertical clearance. 5. The mirror can then be placed on the lateral aspect of the tuberosity, and patients are instructed to open and close. If the mirror intrudes on the mandible’s path during function, horizontal reduction of the tuberosity may be require. Surgery ▪ Local anesthetic infiltration or posterosuperior alveolar and greater palatine blocks. ▪ A crestal incision that extends up the posterior aspect of the tuberosity area. The most posterior aspect of this incision is often best made with a No. 12 scalpel blade. ▪ Reflection of a full-thickness mucoperiosteal flap is completed in the buccal and palatal directions to allow adequate access to the entire tuberosity area. ▪ Bone can be removed using a side-cutting rongeur or rotary instruments, with care taken to avoid perforation of the floor of the maxillary sinus. ▪ If the maxillary sinus is inadvertently perforated, no specific treatment is required, provided that the sinus membrane has not been violated. ▪ The area should be smoothed with a bone file and copiously irrigated with saline. The mucoperiosteal flaps can then be readapted. ▪ Excess, overlapping soft tissue resulting from the bone removal is excised in an elliptical fashion. A tension-free closure over this area is important, particularly if the floor of the sinus has been perforated. ▪ Sutures should remain in place for approximately 7 days. Initial denture impressions can be completed approximately 4 weeks after surgery. Sinus perforation 7  ▪ In the event of a gross sinus perforation involving an opening in the sinus membrane, the use of postoperative antibiotics and sinus decongestants is recommended. ▪ Amoxicillin is usually the antibiotic of choice, unless contraindicated by allergy. ▪ Sinus decongestants such as pseudoephedrine, with or without an antihistamine, are adequate. ▪ The antibiotic and the decongestant should be given for 7 to 10 days postoperatively. ▪ The patient is informed of the potential complications and cautioned against creating excessive sinus pressure such as nose blowing or sucking with a straw for 10 to 14 days. ❖ Buccal Exostosis and Excessive Undercuts Excessive bony protuberances and resulting undercut areas are more common in the maxilla than in the mandible. Surgical procedure ▪ A local anesthetic should be infiltrated around the area requiring bony reduction. ▪ For mandibular buccal exostosis, inferior alveolar blocks may also be required to anesthetize bony areas. ▪ A crestal incision extends 1 to 1.5 cm beyond each end of the area requiring contour, and a full thickness mucoperiosteal flap is reflected to expose the areas of bony exostosis. If adequate exposure cannot be obtained, vertical-releasing incisions are necessary to provide access and prevent trauma to the soft tissue flap. ▪ If the areas of irregularity are small, recontouring with a bone file may be all that is required; larger areas may necessitate use of a rongeur or rotary instrument. ▪ After completion of the bone recontouring, soft tissue is readapted, and visual inspection and palpation ensure that no irregularities or bony undercuts exist. ▪ Interrupted or continuous suturing techniques are used to close the soft tissue incision. ▪ Denture impressions can be completed 4 weeks postoperatively. ▪ Although extremely large areas of bony exostosis generally require removal, small undercut areas are often best treated by being filled with autogenous or allogeneic bone 8  material. Such a situation might occur in the anterior maxilla or mandible, where removal of the bony buccal protuberance results in a narrowed crest in the alveolar ridge area and a less desirable area of support for the denture, as well as an area that may resorb more rapidly. ▪ Local anesthetic infiltration is generally sufficient when filling in buccal undercut areas. ▪ The undercut portion of the ridge is exposed with a crestal incision and standard dissection, or the undercut area can be accessed with a vertical incision made in the anterior maxillary or mandibular areas. ▪ A small periosteal elevator is then used to create a subperiosteal tunnel extending the length of the area to be filled in with bone graft. Autogenous or allogeneic material can then be placed in the defect and covered with a resorbable membrane. ▪ Impressions for denture fabrication can be taken after tissue healing 3 to 4 weeks after surgery.. ❖ Lateral Palatal Exostosis ▪ The lateral aspect of the palatal vault may be irregular because of the presence of lateral palatal. This presents problems in denture construction because of the undercut created by the exostosis and the narrowing of the palatal vault. ▪ Occasionally, these exostoses are large enough that the mucosa covering the area becomes ulcerated. ▪ Local anesthetic in the area of the greater palatine foramen and infiltration in the area of the incision are necessary. ▪ A crestal incision is made from the posterior aspect of the tuberosity, extending slightly beyond the anterior area of the exostosis, which requires recontouring. ▪ Reflection of the mucoperiosteum in the palatal direction should be accomplished with careful attention to the area of the palatine foramen to avoid damage to the blood vessels as they leave the foramen and extend forward. ▪ After adequate exposure, a rotary instrument or bone file can be used to remove the excess bony projection in this area. ▪ The area is irrigated with sterile saline and closed with continuous or interrupted sutures. ▪ No surgical splint or packing is generally required, and the apparent redundant soft tissues will adapt after this procedure. ❖ Mylohyoid Ridge Reduction Interfere with proper denture construction in the mandible. In addition to the actual bony ridge, with its easily damaged thin covering of mucosa. The muscular attachment to this area often is responsible for dislodging the denture. When this ridge is extremely sharp, denture pressure may produce significant pain in this area. 9  In case of severe resorption, the external oblique line and the mylohyoid ridge area may actually form the most prominent areas of the posterior mandible, with the mid- portion of the mandibular ridge existing as a concave structure. In such cases, augmentation of the posterior aspect of the mandible, rather than removal of the mylohyoid ridge, may be beneficial. However, some cases can be improved by reduction of the mylohyoid ridge area. Surgical procedure o Inferior alveolar, buccal, and lingual nerve blocks are required for mylohyoid ridge reduction. o A linear incision is made over the crest of the ridge in the posterior aspect of the mandible. o Extension of the incision too far to the lingual aspect should be avoided because this may cause potential trauma to the lingual nerve. o A full-thickness mucoperiosteal flap is reflected, which exposes the mylohyoid ridge area and mylohyoid muscle attachments. o The mylohyoid muscle fibers are removed from the ridge by sharply incising the muscle attachment at the area of bony origin. o When the muscle is released, the underlying fat is visible in the surgical field. After reflection of the muscle, a rotary instrument with careful soft tissue protection or bone file can be used to remove the sharp prominence of the mylohyoid ridge. o Immediate replacement of the denture is desirable because it may help facilitate a more inferior relocation of the muscular attachment; however, this is unpredictable and may actually be best managed by a procedure to lower the floor of the mouth. ❖ Genial Tubercle Reduction As the mandible begins to undergo resorption, the area of the attachment of the genioglossus muscle in the anterior portion of the mandible may become increasingly prominent. In some cases, the tubercle may actually function as a shelf against which the denture can be constructed, but it usually requires reduction to construct the prosthesis properly. ▪ Before a decision to remove this prominence is made, consideration should be given to possible augmentation of the anterior portion of the mandible rather than reduction of the genial tubercle. ▪ If augmentation is the preferred treatment, the tubercle should be left to add support to the graft in this area. 10  Surgical procedure ▪ Local anesthetic infiltration and bilateral lingual nerve blocks should provide adequate anesthesia. ▪ A crestal incision is made from each premolar area to the mid-line of the mandible. A full-thickness mucoperiosteal flap is dissected lingually to expose the genial tubercle. ▪ The genioglossus muscle attachment can be removed by a sharp incision. ▪ Smoothing with a bur or a rongeur followed by a bone file removes the genial tubercle. ▪ The genioglossus muscle is left to reattach in a random fashion. ▪ As with the mylohyoid muscle and mylohyoid ridge reduction, a procedure to lower the floor of the mouth may also benefit the anterior mandible. ❖ Tori removal (Maxillary Tori) ▪ Maxillary tori consist of bony exostosis formation in the area of the palate. ▪ The origin of maxillary tori is unclear. ▪ Tori are found in 20% of the female population, which is approximately twice the prevalence rate in males. ▪ Tori may have multiple shapes and configurations, 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. ▪ When the loss of teeth necessitates full or partial denture construction, tori often interfere with proper design and function of the prosthesis. ▪ Nearly all large maxillary tori should be removed before full or partial denture construction. ▪ Smaller tori may often be left because they do not interfere with prosthetic construction or function. But small tori need removal if they are irregular, extremely undercut, or in the area where a posterior palatal seal would be expected. Surgical procedure o Bilateral greater palatine and incisive blocks and local infiltration provide the necessary anesthesia for tori removal. o A linear incision in the mid-line of the torus with oblique vertical-releasing incisions at one or both ends is generally necessary. o Because the mucosa over this area is extremely thin, care must be taken in reflecting the tissue from underlying bone, a particularly difficult task when the tori are multiloculated. 11  o A full palatal flap can sometimes be used for exposure of the tori. An incision is made along the crest of the ridge when the patient is edentulous or a palatal sulcular incision is used when teeth are present. Tissue reflection with this type of incision is often difficult if the tori have large undercuts where the bony exostosis is fused with the palate. When tori with a small pedunculated base are present, an osteotome and mallet may be used to remove the bony mass. o For larger tori, it is usually best to section the tori into multiple fragments with a bur in a rotary handpiece. o Careful attention must be paid to the depth of the cuts to avoid perforation of the nasal floor o After sectioning, individual portions of the tori can be removed with a mallet and osteotome or a rongeur; then the area can be smoothed with a large bone bur. o The entire bony projection does not necessarily require removal, but a smooth regular area without undercuts should be created, without extension into the area where a posterior palatal seal would be placed. o Tissue is readapted by finger pressure and is inspected to determine the amount of excess mucosa that may require removal. o Retention of enough tissue to allow a tension-free closure over the entire area of exposed bone is important. o The mucosa is reapproximated and sutured; an interrupted suture technique is often required because the thin mucosa may not retain sutures well. o To prevent hematoma formation, some form of pressure dressing must be placed over the area of the palatal vault. A temporary denture or prefabricated splint with a soft liner placed in the center of the palate to prevent pressure necrosis can also be used to support the thin mucosa and prevent hematoma formation. o The major complications of maxillary tori removal include postoperative hematoma formation, fracture or perforation of the floor of the nose, and necrosis of the flap. o Local care, including vigorous irrigation, good hygiene, and support with soft tissue conditioners in the splint or denture, usually provides adequate treatment. ❖ Mandibular Tori ▪ 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 slowly increase 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. 12  ▪ 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. Surgical procedure ▪ Bilateral lingual and inferior alveolar injections provide adequate anesthesia for tori removal. ▪ A crest of the ridge incision should be made, extending 1 to 1.5 cm beyond each end of the tori to be reduced. ▪ When bilateral tori are to be removed simultaneously, it is best to leave a small band of tissue attached at the mid-line between the anterior extent of the two incisions. ▪ Leaving this tissue attached helps eliminate potential hematoma formation in the anterior floor of the mouth and maintains as much of the lingual vestibule as possible in the anterior mandibular area. ▪ As with maxillary tori, the mucosa over the lingual tori is generally very thin and should be reflected carefully to expose the entire area of bone to be recontoured. ▪ When the torus has a small pedunculated base, a mallet and osteotome may be used to cleave the tori from the medial aspect of the mandible. ▪ The line of cleavage can be directed by creating a small trough with a bur and a handpiece before using an osteotome. ▪ It is important to ensure that the direction of the initial bur trough (or the osteotome if it is used alone) is parallel with the medial aspect of the mandible to avoid an unfavorable fracture of the lingual or inferior cortex. ▪ The bur can also be used to deepen the trough so that a small instrument can be levered against the mandible to fracture the lingual tori to allow its removal. ▪ A bone bur or file can then be used to smooth the lingual cortex. ▪ The tissue should be readapted and palpated to evaluate contour and elimination of undercuts. ▪ An interrupted or continuous suture technique is used to close the incisions. ▪ Gauze packs placed in the floor of the mouth and retained for several hours are generally helpful in reducing postoperative edema and hematoma formation. ▪ In the event of wound dehiscence or exposed bone in the area of a mucosal perforation, treatment with local care, including frequent vigorous saline irrigation, is usually sufficient. 13  ❖ Alveolar ridge preservation ▪ An important aspect of preprosthetic surgery can actually done at the time of tooth extraction by attempting to maintain and regain as much bone in the extraction area as possible. ▪ Preservation of the socket after extraction using a variety of bone materials can aid in the maintenance of alveolar height and width. ▪ The adjunctive measures maintain ridge form as the alloplastic materials are slowly resorbed through bony remodeling. ▪ Several allogeneic and xenogeneic bone materials have been used to maintain the bony architecture, limiting the morbidity of harvesting autogenous bone from an adjacent intraoral site. ▪ These inorganic materials are derived from a bovine source (xenograft) or processed cadaveric bone. ▪ Atraumatic extraction with maintenance of the buccal and lingual cortical walls is essential to preservation of alveolar bone. ▪ The site is curetted and irrigated after removal of the tooth in entirety. ▪ The graft material is placed into the extraction site and compressed to the level of the alveolar crest. ▪ The extraction site usually is not closed primarily. ▪ In most cases, the graft material is covered with some type of collagen material that is held in place with resorbable sutures. ▪ The use of a resorbable membrane requires limited soft tissue reflection of the adjacent margins to place the membrane under the attached gingiva. ▪ Mucosal re-epithelialization occurs over the grafted site within a few weeks ▪ Implant placement in a site preserved with grafted bone material usually proceeds in 2 to 6 months. Alveolar ridge preservation. A, Extraction of teeth. B, Allogeneic material is placed in extraction site to height of alveolar crest. C, Resorbable membrane placed over graft and stabilized with bolster stitches to allow secondary intention over crest. ‫نتمنى لكم ولنا التوفيق مع بداية العام الدراسي الجديد‬ Dear stuDents I corDIally congratulate you on the begInnIng of a new acaDemIc year! 14