Preprosthetic & Reconstructive Surgery PDF

Preprosthetic & Reconstructive Surgery - P reprosthetic surgery is the procedures designed to optimize the retention, support, stability and comfort of the prosthesis by the selective modification of soft and hard tissues. - The old concept was to prepare or improve the patient’s ability to wear a...

Preprosthetic & Reconstructive Surgery - P reprosthetic surgery is the procedures designed to optimize the retention, support, stability and comfort of the prosthesis by the selective modification of soft and hard tissues. - The old concept was to prepare or improve the patient’s ability to wear a complete or partial denture utilizing corrective soft tissue and bony tissue surgeries. However, nowadays after the invention of osseointegrated dental implants by Prof. Branamark in late 1970’s this concept has changed to become “Pre implant Surgeries”. - After tooth loss the alveolar bone immediately begins to resorb due to lack of stresses placed in this area by teeth and periodontal ligament. The greatest bone resorption occurs within the first 6 months after tooth loss with as much as 40% of the alveolar height & 60% of the alveolar. The mandible resorbs 4 times greater than the maxilla. The amounts of bone resorption vary from one individual to the other, although the resorption pattern is the same. Where there is greater resorption of buccal plate compared to palatal/lingual plate and the center of the ridge shifts palatally/lingually reducing the total arch length. - Causes of bone loss: 1) Before tooth extraction: i) Traumatic occlusion ii) Periodontal disease iii) Endodontic lesions 2) After tooth extraction: i) Traumatic extraction ii) Mucoperiosteal loading by a dental prosthesis iii) Disuse atrophy (Bone requires stimulation often referred to as "minimum essential strain" to maintain itself. Both insufficient strain & excessive loads can lead to bone loss) iv) Anatomic factors (Patients with short faces have greater biting forces) v) Nutritional abnormalities vi) Systemic bone disease (Osteoporosis) vii) Endocrine dysfunction - Sequlea (consequences) of edentulism: 1. Maxillary and mandibular ridges will become shorter and narrower. 2. Interach distance will increase. 3. Attachments of the circumoral and floor of the mouth musculature will become more superficial. 4. Attached and unattached mucosa will be significantly reduced. - Inorder to achieve our goals we should go through the following steps: STEP 1: Patient evaluation - History of the patient's success or failure in maintaining previous prosthesis. - Evaluation of the functional & esthetic expectations (realistic vs unrealistic) - Medical history of the patient (renal dysfunction, Vitamin D deficiency, metabolic diseases including serum Ca & Ph, albumin and alkaline phosphatase). 1  Preprosthetic & Reconstructive Surgery STEP 2: Examination of supporting hard & soft tissues (Problem oriented physical examin.) i- Inspect & palpate the maxilla, mandible, & interarch relationship - The criteria of an ideal ridge are: 1) Adequate bony support free of sharp bony edges, bony tori & undercuts. 2) Mucoperiosteum should be healthy & of even thickness. (Too thin mucoperiosteum is liable to be ulcerated under the denture, while too thick mucoperiosteum will undermine the stability of the denture) 3) Denture bearing area should be free of tender soft tissue scars, prominent fibrous bands, hypertrophied tissues, and pathological tissues. 4) Adequate sulcus depth free of high frenal attachments & high muscle attachments which impair denture sealing & retention. ii- Radiographic evaluation 1) Panorama (best view to evaluate & survey bony structures & pathologies) 2) Lateral cephalometry & PA (used to evaluate interarch space) 3) Dental CT or Cone beam CT (used in treatment plan of complex cases) iii- Study model evaluation STEP 3: Treatment planning consideration - Consider long term benefits and maintenance - Staging of the surgical procedures - Bony surgery followed by soft tissue surgeries - Classification of preprosthetic surgical procedures: I) Preventive procedures - Atraumatic extraction technique - Socket augmentation/Ridge preservation - Partial extraction therapy II) Corrective procedures a) Hard tissue surgery - Simple Alveoloplasty - Intraseptal Alveoloplasty - Removal of exostosis & undercuts - Removal of tori - Correction of prominent mylohyoid ridge - Correction of prominent genial tubercles b) Soft tissue surgery - Labial frenectomy - Lingual frenectomy - Removal of lesions by ill-fitting dentures c) Combined soft & hard tissue surgery - Reduction of enlarged maxillary tuberosity III) Ridge atrophy procedures - Vestibuloplasty - Ridge augmentation - Implants 2  Preprosthetic & Reconstructive Surgery I) Preventive Procedures 1) Atraumatic extraction procedures: - It is the extraction of all of the tooth roots without removing or fracturing the surrounding supporting alveolar bone. i) Periotomes: severing (cutting) of periodontal ligament fibers ii) Luxators: severing (cutting) of periodontal ligament fibers and dilates the extraction socket iii) Physics forceps: It has a Beak & Bumper design, where the beak is placed in the depth of the gingival lingual sulcus and the bumper is placed buccally at the mucogingival junction. The bumper is large in size to support buccal bone & applies compressive forces on it. The Physics forceps requires minimal strength & maximum patience; it applies constant & continuous force on PDL. Biomechanical principles; Moment of force (8 times), Creep & Stress distribution iv) Vertical Extraction Systems (Benex System): It is composed of; Drill, Self tapping screw, Impression tray, pull-string and the Benex extractor. The main draw back is that it is only effective with teeth with single roots, sometimes premolars could be extracted. Roots must be straight and slender with no curvatures. 2) Socket Augmentation/Ridge preservation: - Prevention of post extraction alveolar bone loss was first described by Greenstein and colleagues and Ashman & Bruins in 1985. The term Socket Preservation was first coined by Cohen in 1988, and it was decided in 2007 to use this term with fresh extraction sockets having an intact buccal bony wall. The term Ridge Preservation was more appropriate for extraction sockets with deficient buccal bony walls. - It is a surgical procedure in which a graft material or scaffold is placed in a fresh extraction socket to preserve the alveolar ridge. - The rationale for it is to minimize the resorption of the alveolar ridge and to maximize bone formation within the socket. - All bone grafting material can be used to augment the extraction socket, however the ideal graft material for socket augmentation should prevent the volume reduction after tooth extraction, and remain in situ as a scaffold until bone formation has occurred. - Indications for socket augmentation are; for esthetic reasons at pontic sites in conventional fixed prosthodontics or when an implant might not be planned in the near future, to retain the possibility of an implant option for the patient in the future. 3) Partial Extraction Therapies: Are a subgroup of precollapse interventions that collectively use the tooth itself to offset the loss of alveolar tissue. By retaining the tooth root and its attachment to bone, the Bundle Bone-PDL complex with its vascular supply may be maintained. 3  Preprosthetic & Reconstructive Surgery I) Root Submergence: A technique that aims to preserve the ridge and development of pontic sites beneath Fixed partial dentures. It requires absence of apical pathology, and that endodontic treatment first successfully to be carried out. The tooth is decoronated at the level of the bone crest and the coronal root hollowed to mimic the future ovate pontic. II) Socket Shield: A technique that uses the facial root section alone to maintain the tissues at immediate implant placement, with the aim to prevent the buccopalatal ridge collapse. The tooth is sectioned mesiodistally such that the facial and palatal root halves are separated. The palatal root section is removed, leaving the facial root section to remain with its attachment to the socket remaining undisturbed. III) Pontic Shield: A technique that develops a pontic site and preserves the alveolar ridge by retaining the facial root section, the extraction socket is grafted with a slow-resorbing bone substitute material, and then the tooth socket is sealed with a soft tissue graft. It provides the clinician with an alternative method when apical pathology contraindicates root submergence in pontic sites. IV) Proximal Socket Shield: A technique that uses the proximal root section to maintain the tissues at immediate implant placement, with the aim to preserve the interdental papillae. It is planned when immediate implant placement sites of two or more adjacent implants. II) Corrective Procedures Of Bony Tissue Abnormalities 1) Alveoloplasty & Alveolectomy: (Bony Recontouring Procedures) - Definition: - Alveoloplasty: "Surgical contouring of the alveolar process". - Alveolectomy: "Surgical removal of the alveolar process". - This procedure was only done in the past when it was thought that the alveolar process was to be removed completely if jaw was to be subjected to radiation. Today only partial alveolectomy is done, example removal of bony exostosis, bony undercut or sharp bony edge. - Alveolotomy: "Surgical cutting into the alveolar process". - This procedure includes cutting through the alveolar process to gain access to an impacted tooth, remaining root, cyst or any other pathological lesion. - N.B: The terms alveoloplasty & alveolectomy are used interchangeably. 4  Preprosthetic & Reconstructive Surgery - Objectives: 1) Correction of abnormalities & deformities of the alveolar ridge 2) Obtaining a smooth round ridge after multiple extraction - Types: I) Simple alveoplasty II) Intraseptal alveoplasty (I) Simple Alveoloplasty: # Definition: It is the surgical procedure performed to smoothen or recontour the alveolar bone found at the time of tooth extraction (Preventive) or after a period of initial healing (Corrective) to allow the ridge to receive a final removable prostheses. # Indications: - Sharp bony edges found at time of extraction or after healing. # Technique: - Incision: - Bony areas requiring recontouring should be exposed using an envelope type of flap. Where adequate exposure is not possible, small vertical- releasing incisions may be done. - Ridge Contouring: - It can be accomplished with a rongeur, a bone file, or a bone bur in a handpiece, alone or in combination. - Bone removal should be conservative because extensive bone removal leads to rapid uncontrolled bone resorption. - A bone file is used to smoothen any sharp bony edges to obtain a round flat uniform ridge. - After copious irrigation to ensure removal of debris, the tissue margins can be reapproximated with interrupted or continuous sutures. - When a sharp knife-edge ridge exists in the mandible, the sharp superior portion of the alveolus can be removed (Plateau). (II) Intraseptal Alveoloplasty: - A surgical procedure that involves 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. # Contraindications: - In posterior teeth due to lack of accessibility. # Indications: - 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. 5  Preprosthetic & Reconstructive Surgery #Disadvantages: The decrease in ridge thickness that obviously occurs with this procedure, which may preclude placement of implants in the future #Technique: - Extraction of teeth: - Proclined teeth are extracted using forceps in this sequence; 3 then 2 then 1 inorder to preserve the integrity of labial plate. Extraction of 3 after 21 may result in fracture of labial plate because bone over canine eminence is very weak. - Removal of interseptal bone: - A bone ronguer is used to remove the interseptal bone between the extracted teeth completely, which is done by inserting the blades of the ronguer as deep as possible in the adjacent sockets to ensure repositioning of the labial plate without difficulties. - Fracturing the labial plate: - Digital finger pressure on the outer labial plate of bone is used to create a horizontal fracture of the labial cortical plate at the level of the apices of the empty sockets. - Ridge molding: - Ridge is molded into shape by compressing the labial plate of bone until it contacts the palatal plate of bone. 2) Palatal & Mandibular tori: - Definition: "Are developmental congenital bony overgrowth." - Incidence: 20-25% of the population - Shape: Vary in shape and they maybe single, multiple or lobulated - Site: - Torus Palatinus à Midline of the palate. - Torus Mandibularis à Lingual aspect of the mandibular canine premolar region bilaterally. - Indication for removal: Treatment is usually not necessary unless: 1) When they act as mechanical fulcrum under the denture & affect its stability. 2) When they produce pain & ulceration of the thin mucosa covering the torus. 3) Before denture construction especially when they are greater than 3mm in height as they will prevent denture construction. 4) Cancerphobic patients 5) When they interfere with speech 6  Preprosthetic & Reconstructive Surgery - Technique: (A) Torus Palatinus: - Anaesthesia: - Bilateral greater palatine nerve blocks & nasopalatine nerve block. - Field block anaesth. for hemostasis & to help balloon thin palatal tissues - Incision: Double Y incision - A straight incision is made on the midline of the palate from posterior to anterior ends of the torus. - Lateral releasing incisions are made at each end of the straight incision. - Advantages: i- Adequate accessibility ii- Excellent exposure iii- Avoids injury of greater palatine & nasopalatine nerves and vessels. - Flap reflection: - Reflection of the flap is difficult due to absence of connective tissue under the palatal mucosa which is firmly adherent to the underlying bone. - Therefore reflection of the flap should be done carefully to avoid laceration of the thin mucosa covering the torus. - Removal of the bony mass: - A round bur is used to drill holes inorder to divide the bony mass and indicate the depth of removal. - Holes are then connected together using a fissure bur. - The bony segments are then removed using a unibevel chisel, where they could later on be used as a source for bone graft if needed. - Smoothening of bone is then done using bone files or large burs. 7  Preprosthetic & Reconstructive Surgery - Flap reflection & suturing: - The flap is reflected; excess soft tissue is excised, & then sutured in place. - A prefabricated clear acrylic palatal stent is worn by the patient for the first 48hrs to prevent hematoma formation under the flap. - Complications: 1) Palatal fracture or perforation of the nasal floor due to wrong application of chisels or due to deep drilling of holes anteriorly. 2) Postoperative hematoma formation. 3) Bleeding due to injury of greater or nasal palatine vessels 4) Necrosis of flap (B) Torus Mandibularis: - Anaesthesia: - Inferior alveolar & lingual nerve blocks - Lingual infiltration for heamostasis & to help balloon the thin lingual tissues. - Incision: - Crestal incision extending from the 1st molar area of one side to that of the other side. (Never to do oblique incisions) - Flap reflection: - Flap is reflected lingually for about 1cm beyond each end of the tori. - No releasing incisions are done on the lingual aspect of the mandible to avoid injuring of the lingual nerve. - Tori removal: - A piece of gauze is placed betw. the flap & the mandible below the torus, inorder to prevent the loss of the excised bone into the sublingual space. - The tori are then removed using either large surgical bur or unibevel chisel. 8  Preprosthetic & Reconstructive Surgery - When chisel is used a groove should be made at the superior aspect of the torus into which the unibevel chisel is lodged. - Bone is smoothened & wound is irrigated. - Suturing: - The excess soft tissue is excised. - The flap is sutured using continuous sutures with lock (in edentulous cases) or interrupted sutures with the knot placed buccally (in dentulous cases). - Complications: - Laceration of flap (don’t suture it, leave it to heal by 2ry intension) - Lingual paraesthesia - Expanding hematoma in floor of the mouth which may obstruct the airway 3) Bony exostosis: - Indication for removal: Treatment is usually not necessary unless: 1) When they act as mechanical fulcrum under the denture & affect its stability. 2) When they produce pain & ulceration of thin mucosa covering the exostosis. 3) Patient is cancer phobic 4) A source of autogenous bone graft is needed - Site: Maxilla > Mandible - Technique: - A local anesthetic should be infiltrated around the area requiring bony reduction. - 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. Vertical-releasing incisions are sometimes needed. - If the exostosis is small, recontouring with a bone file may be all that is required; larger exostosis may necessitate use of a rongeur or bur. - Interrupted or continuous suturing techniques are used to close the soft tissue incision. - Areas of undercuts are often best treated by being filled with autogenous or allogeneic bone material and covered by a membrane. 3) Prominent genial tubercles: - Site: Anterior region of the mandible when bone is severely resorbed the area of the attachment of the genioglossus muscle may become increasingly prominent. 9  Preprosthetic & Reconstructive Surgery - Signs & Symptoms: - Severe pain under the denture due to compression of the soft tissue between the denture base & the sharp bone. - Trapping of the submandibular papillae between the lingual flange of the denture and enlarged genial tubercles results in decrease of salivary flow. - Technique: - Infiltration & 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 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. 4) Sharp mylohyoid ridge: - Site: - Lingual aspect of post. part of the mand. giving attachment to mylohyoid ms. - Signs & Symptoms: - Two problems are encountered in this case; i) A sharp, prominent mylohyoid ridge causing severe pain under the denture due to compression of the soft tissue between the denture & the sharp bone. ii) A highly attached mylohyoid muscle preventing the lingual extension of the lingual flange of the denture & continuously affecting the stability of the denture. - Technique: - Anaesthesia: - Inferior alveolar & lingual nerve blocks & infiltration for hemostasis - Incision & flap reflection: - A crestal incision is made along the crest of the ridge extending from the 3rd molar region to the canine region. (No releasing incisions are done lingually) - The flap is then reflected lingually to expose the mylohyoid ridge & its attached muscle. - Removal of mylohyoid ridge: - The mylohyoid muscle fibers are sharply released from the mylohyoid ridge. - A rotary instrument or a bone ronguer is then used to reduce & smooth the mylohyoid ridge. - Immediate wearing of a denture is essential as it will cause the fibers of the mylohyoid muscle to reattach at a lower level plus it aids in heamostasis. - Closure: - Bleeding should be controlled before closure. - Continuous with lock suturing 10  Preprosthetic & Reconstructive Surgery III) Corrective Procedures Of Soft Tissue Abnormalities 1) Short labial frenum: - Problems: - The presence of a short labial frenum results in denture instability, which may necessitates a reduction in the height of the denture flange at this site but this will impair the denture retention due to interference with peripheral seal. - A short frenum may result in facial gingival recession of anterior teeth and may result in incision line openings when they are included in the flap. - A muscular frenum may also be the cause of diastema resulting in dental problems. - Classification: (Classified by Placek 1974), as: Mucosal – when the frenal fibres are attached up to the mucogingival junction. Gingival – when the fibres are inserted within the attached gingiva. Papillary – when the fibres are extending into the interdental papilla. Papilla penetrating – when the frenal fibres cross the alveolar process and extend up to the incisive papilla. - Technique: Frenectomy is the complete removal of the frenum, including its attachment to the underlying bone. It can be accomplished either by the routine scalpel technique, electrosurgery or by using lasers. # Simple excision technique: - Anaesthesia: - Labial infiltration is performed. - Incision & excision of the frenum: - The lip is raised, pulled forward & tensed. - Two straight artery forceps are used to clamp the frenum. (One placed parallel to the alveolar ridge in contact with the mucosa & the other placed parallel to the lifted & pulled-out lip). - The frenum is then excised using a #11 blade by placing the blade under the two artery forceps & performing two elliptical incisions. - Suturing: - The margins of the wound are undermined to allow suturing without excessive tension. - The wound is then irrigated with normal saline and sutured. - The first suture should be at the maximal depth of the vestibule. - If excessive tension is found on the suture line, the labial 11  Preprosthetic & Reconstructive Surgery portion of the incision is sutured, & the alveolar portion is left open and covered by a surgical pack to heal by secondary epithelialization. 2) Short lingual frenum (Ankyloglossia) or (Tongue tie): - Definition: Congenital condition in which the tongue is attached to floor of the mouth - Signs & Symptoms: - Inability to protrude the tongue - Inability to clean away food from the palate & labiobuccal sulci. - Speech difficulties - Impairment of lower denture stability & retention. - Difficulty to breast feed - When it results in orthodontic problems, such as anterior and posterior cross bites, and open bite - Technique: - Anaesthesia: - Bilateral lingual nerve block OR general anaesthesia can be used. - Incision: - The mouth is opened & maintained open by using a mouth prop. - The tongue is grasped & a suture is passed through its midline 1cm from the tip to facilitate its retraction. - The tongue is lifted up as high as possible to stretch the lingual frenum. - The frenum is then cut horizontally midway between the floor of the mouth & the tip of the tongue using a sharp scissor. - The cut is directed posteriorly parallel to the floor of the mouth, extending to the attachment of the under surface of the tongue with the floor of the mouth or when the tip of the tongue can touch the palatal aspect of the upper incisors. - The horizontal cut resulted in a vertical wound. - During the incision take care not to injure submand. gld duct & lingual vein. - Suturing: - Margins of wound are undermined to allow suturing without excessive tension - The wound is closed using interrupted or continuous resorbable sutures. 3) Lesions caused by ill fitting dentures: i) Flabby ridge: - Site: Anterior region of the maxilla - Etiology: - Patients with full upper denture opposed with natural lower anterior teeth have their upper anterior region subjected to excessive occlusal trauma which causes bone resorption & inflammatory hyperplasia of the soft tissues. - Technique: - Incision: - After securing L.A, excess soft tissue is grasped with 1 or more Allies forceps. - Elliptical incision is performed deep to the bone along the crest of the ridge. - The strip of excess tissue (only the nonkeratinized) is removed & biopsied. 12  Preprosthetic & Reconstructive Surgery - Suturing: - The edges of the incision are undermined & the wound is sutured. ii) Epulis fissuratum (Inflammatory fibrous hyperplasia): - Etiology: Wearing ill fitting dentures where it’s flanges causes excessive growth of the tissues in the mucobuccal fold of the upper or lower jaw. - Clinical picture: Two or more inflamed folds of tissues separated by a central groove into which fits the denture border. - Technique: (Surgical excision or excisional biopsy) - Incision: - After securing infiltration anesthesia, the lesion is grasped with Allies forceps or sutures. - The lesion is dissected out by incising the mucosa around the base of the lesion using number 15 blade, & then biopsied. - Denture: reduction of the overextended denture flange or remake of denture iii) Inflammatory papillary hyperplasia of the palate: - Severely inflamed localized area under the denture due to bacterial or fungal growth. It usually occurs in edentulous patients who have been wearing dentures for a long time and is possibly due to inflammatory hyperplasia of the mucosa because of chronic local irritation, such as food accumulation and smoking. - Treatment: Removal of the denture Antifungal agents (Nystatin or Clotromidazole) Surgical treatment which consists of removal of the lesion with a scalpel or electrosurgical loop. Healing is achieved by secondary intention. Good oral & denture hygiene (brush denture & use daktarin gel) Denture should fit well (reline or remake) and not be worn at night iv) Irritation fibroma (Leaf-like denture fibroma): - is a variant of irritation fibroma that is flat and grows on the hard palate under the maxillary denture bases. A fibroma beneath a denture has no room to expand uniformly in all directions & so develops as a pancake-shaped (leaf-like) mass, which maybe associated with underlying bony erosion. Clinically it’s a flattened pink mass attached to the palate with a narrow stalk. - Treatment: Surgical excision or excisional biopsy 13  Preprosthetic & Reconstructive Surgery IV) Corrective Procedures For Combined Bony & Soft Tissue Abnormalities 1) Enlarged maxillary tuberosity: - Horizontal &/or vertical excess of the maxillary tuberosity area may result from excess bone, soft tissues or both. - Indications: Bony irregularities and undercuts / To create an adequate interarch space / Chronic irritation / Inability to construct a prosthesis - A preoperative panoramic radiograph is essential to: i) Determine the extent to which bone & soft tissue contribute to this enlargement. ii) Locate the floor of the maxillary sinus & its relation to the max. tuberosity. a) Soft tissue enlarged maxillary tuberosity: - Technique: - Measuring the soft tissue thickness: - The amount of soft tissue enlargement is measured either by "ridge mapping" where a sharp probe with a stopper is inserted in the soft tissue over the crest of the ridge at the tuberosity area after securing local anaesth., or by “sounding” where a local anaesth. needle is inserted in the soft tissue, or by “Panorama”. - Incision: - An elliptical incision is made over the tuberosity. - Soft tissue reduction: - A canoe shaped wedge section of soft tissue is removed. - Margins are undermined to allow tension free soft tissue closure. - Closure: - Wound is closed with continuous with lock sutures. b) Bony tissue enlarged maxillary tuberosity: - Technique: - Anaesthesia: - Post. Sup. Alv. & Greater Palatine nerve blocks or infiltration anaesthesia. 14  Preprosthetic & Reconstructive Surgery - Incision & flap reflection: - A crestal incision is made over the tuberosity. - The flap is then reflected both in the buccal & palatal directions to allow adequate access to the entire tuberosity area. - Bone removal: - Bone is removed using side cutting ronguer &/or rotary instrument. - Care should be taken not to perforate the maxillary sinus during bone removal so as not to create an oroantral communication. - Bone is then smoothed using bone file. - Suturing: - The flap is then repositioned, & excess soft tissue is excised. - A tension free closure is performed using interrupted sutures. V) Management Of Alveolar Ridge Atrophy - Classification of alveolar ridge atrophy (Cawood & Howell classification): Class I: Dentate Class II: Postextraction Class III: Convex ridge form (adequate height & width of ridge) Class IV: Knife edge form (adequate height & inadequate width of ridge) Class V: Flat ridge form (loss of alveolar process) Class VI: Loss of basal bone - Methods of treatment: 1) Vestibuloplasty (sulcus deepening): - Used when there is adequate bony height (at least 15mm) 2) Ridge augmentation (ridge grafting): - Used when the ridge is deficient in height &/or in width 3) Implants: - Used when there is adequate bony height and width - It is used alone or in combination with other methods Vestibuloplasty (Sulcus deepening) (Ridge extension procedure) - Definition: It is a soft tissue procedure that aims to increase the depth of the buccal, labial or lingual sulci that have been obliterated by abnormal high muscle attachments or presence of scar tissue. - Techniques: 1) Transpositional flap vestibuloplasty 2) Vestibuloplasty with tissue grafting 3) Submucosal vestibuloplasty 4) Lingual sulcus vestibuloplasty 15  Preprosthetic & Reconstructive Surgery Secondary epithelialization vestibuloplasty: - Indication: - Adequate bony ridge height with high muscle attachments or hyperplastic mucosa obliterating the sulcus, in the anterior region of both the mandible & the maxilla. - Technique: - Incision: - Secure local or general anaesth.,then the lip is stretched out & protruded. - A mucosal incision is carried out beginning in the mucobuccal fold at the 1st molar region of one side, then upward to just below the crest of the ridge crossing the midline to reach the opposite 1st molar region in the same way - Flap reflection: - The mucosal layer is then dissected bluntly from the underlying periosteum & muscle fibers for a distance of 1.5-2.5 cm. - Cutting the muscles: - The mentalis muscle is bluntly dissected with a periosteal elevator. - The muscle is grasped between the peaks of a mosquito where it is cut by two incisions, below & above the peak. - Suturing the mucosal flap: - The mucosal flap is sutured to the periosteum at the depth of the sulcus. - Some surgeons prefer to tie the mucosal flap to the periosteum by sutures which pass out through the soft tissue and skin overlying the chin. The suture is tied to a button. - The exposed strip of periosteum: - Maybe covered by a periodontal pack which promote healing by 2ry intention (2ry epithelialization). - Maybe covered by a prefabricated clear acrylic splint attached to the mandible by circumferential wiring for 2-3 weeks, this will help to protect the exposed periosteum & to preserve the new depth of the sulcus during healing. 16  Preprosthetic & Reconstructive Surgery Ridge Augmentation - Indication: When the ridge is deficient in height &/or in width. - Source (Types): i) Autogenous bone grafts - Site: # Extraoral sites: 1) Iliac crest (Provides large amounts of corticocancellous bone) 2) Calvaria 3) Rib 4) Tibia # Intraoral sites: 1) External oblique ridge (Ant. border of ramus) provides cortical bone 2) Mental protuberance (Symphysis) provides corticocancellous bone 3) Maxillary tuberosity 4) Tori or exostosis - They are the best grafting material (Gold standard) because: 1) No Ag-Ab reaction (No rejection) 2) No risk of infection 3) Not expensive 4) Offers best quality of bone as they contain osteoproginator cells 5) Availability - Disadvantage: à Donor site morbidity and rapid resorption - Harvested by: à Bone scrapper, surgical bur, trephine bur or chisel & mallet ii) Allogenic bone graft (Homologous) - They come from another person (cadavers), and to avoid tissue rejection they must be rendered non-antigenic. iii) Xenogenic bone graft (Heterogenous) - They come from animals iv) Alloplastic bone graft - They include hydroxyapatite, bioactive glass, & tri-calcium phosphate - Biological mechanism: # When bone graft is placed at the recipient site, its osteoblasts will remain vital for 7 days & they will form bone. (Osteogenesis) (Occurs with autografts only) # The graft contain substances called bone morphogenic proteins (BMPs) which stimulate undifferentiated mesenchymal cells & bone producing cells at the recipient site to form bone. (Osteoinduction) (Occurs with autografts and allografts) # The graft will act as a scaffold or a meshwork to allow the ingrowth of capillaries & osteoblasts from recipient site. (Osteoconduction) (Occurs with all types of grafts) # Bone formation starts at the edges of the graft, at same time the graft undergo bone resorption until it's completely replaced by the forming bone. (Creeping substitution) 17  Preprosthetic & Reconstructive Surgery A) Narrow (knife-edge) ridge (Class IV): 1) Ridge splitting: - Technique: - A minimum ridge width of 3mm is required inorder to perform this technique. - A midcrestal osteotomy is done to separate the buccal & lingual cortices. - The labial segment is mobilized carefully with an osteotome, and then an interpositional bone graft (sandwich graft) can be placed in the resulting defect. Then an implant can be placed 3-4 months later. - The implant can sometimes be placed at the same time with the ridge split procedure. 2) Veneer block graft: - Technique: - An autogenous block bone graft is secured with screws on the buccal aspect of the knife edge ridge. - Advantages: - Advantages of autogenous bone plus the lower cost (cost of fixation screws only) - Disadvantages: 1- Donor site morbidity 2- Rapid resorption of the graft 3- Unpredictable results 4- Technique sensitive 3) Ridge expansion (Osteotomes or Densah burs): - Technique: - Bone is expanded rather than being cut by a special type of drills (Densah burs) that are rotated in an anti clockwise direction. 4) Bone Shell Technique (Khoury): - Technique: - This technique aims to horizontally graft deficient ridges using autogenous or allograft shell technique. The shell with a thickness of less than 1 mm is fixated with titanium microscrews, and the distance between the shell and the residual bone will be filled with particulate bone graft. 5) Guided Bone Regeneration: - Guided bone regeneration (GBR) was introduced as a therapeutic modality aiming to achieve bone regeneration, via the use of barrier membranes. Those occlusive membranes, which mechanically exclude non-osteogenic cell populations from the surrounding soft tissues, thereby allowing osteogenic cell populations originating from the parent bone to inhabit the osseous wound. 6) Titanium Mesh and BMP: 18  Preprosthetic & Reconstructive Surgery A) Vertically deficient (flat) ridge (Class V): 1) Vertical alveolar distraction osteogenesis: - Technique: i) Surgery: - A horizontal osteotomy is done to separate the alveolar process into upper & lower parts. - A distraction device is secured to both the superior & lower bone parts. ii) Latency period: - Wait from 4-7 days depending on the age of the patient, to allow primary soft tissue healing and callus to form. iii) Activation (Distraction) period: - Distraction begins at a rate 1mm/day (0.25mm 4 times/day). - Less than 1mm/day à Healing at osteotomy occurs. - More than 1mm/day à Fibrous tissue will form instead of bone. iv) Consolidation period: - From two to four times that of the distraction period to allow for the stabilization of the distracted segments (i.e. woven bone to change and mature into lamellar bone). v) Implant placement: - After the consolidation period. - Advantages: 1- Shorter rehabilitation time (3-4 months) 2- Enlarge both bone & soft tissue 3- No donor site morbidity 4- More predictable results - Disadvantages: 1- High cost 2- Annoying to the patient 3- Technique sensitive 2) Block Onlay graft: - Technique: - Includes the securing of rib graft or iliac crest graft by screws on the superior border of the mandible after drilling in it holes with a bur (regional acceleratory phenomenon), to increase blood supply in the graft site. - The graft is contoured to adapt to the configuration of the mandible. - Disadvantages: 1- Donor site morbidity 2- Long healing period (6-8 months) 3- Significant resorption of the graft 19  Preprosthetic & Reconstructive Surgery 3) Sandwich or Interpositional graft augmentation: - Technique: - A Horizontal osteotomy on the mandible or maxilla is done. - The superior segment of the mandible or the maxilla is repositioned superiorly to improve the ridge height & contour. - The repositioned bony segment is fixed in the new position with plates and screws. - The gap formed is filled with either autogenous cancellous bone or any other bone graft particulates. - Advantages: 1- ↓ bone resorption 2- ↓ donor site morbidity 3- ↓ healing period (3-5 months) 4) Titanium reinforced membranes for vertical GBR: - Technique: - The Ti reinforced membrane is fixed by screws to the bone inorder to: i) Protect the underlying bone graft & implants until bone is formed after 6months. ii) Prevent the rapid ingrowth of fibrous tissue and allow time for the slow growth of bone (Guided bone regeneration) 5) Use of short implants: - Its not a method to augment the ridge, but it is a method to manage flat ridges. - The use of multiple short implants is an available option to restore the vertically deficient posterior maxilla and mandible to avoid open maxillary sinus augmentation and mandibular nerve transposition techniques. - The short implants are available in 4mm and 6mm heights - Its always recommended to splint the restorations. 6) Inlay bone graft (Sinus Augmentation): - Idea: - It is a bony augmentation procedure in which the graft material is placed inside the sinus to augment the bony support of the alveolar ridge to later receive an implant. - Technique: - After securing local anaesthesia, an opening is made on the lateral wall of the maxilla. - The sinus lining is carefully elevated from the bony floor of the sinus. - An autogenous (bony window itself maybe used) or other bone grafting substitutes is then inserted under the sinus lining in contact with the sinus bony floor. - The lateral window is covered by resorbable membrane to prevent extrusion of the graft material. - The graft is allowed to heal for 4-6 months before implant placement. 20  Preprosthetic & Reconstructive Surgery 7) Zygoma implants: - Indications: - Severely flat ridges - Technique: - An extremely long implant (30-52mm) is placed through the crest of the posteriorly resorbed maxilla transantrally into compact bone of the zygoma after taking a preoperative CT scan. - Advantages: 1- Treatment time is reduced 2- No donor site morbidity 3- Less invasive and bone graft survival isn’t considered - Disadvantages: 1- Risk of injury of adjacent vital structures 2- Risk of postoperative sinusitis 3- Failed implants are very difficult to remove 8) Pterygoid implants: Are endosseous implants placed into the pterygoid plates incases with severe flat ridges. 9) Titanium Mesh and BMP: 10) Nasal floor augmentation: 21