Category Archives: Preprosthetic Surgery

Sinus lift

Sinus lift

Rehabilitation ‘of the maxilla lising implants is frequently problematic because of the extension of thcmaxlllarv sinus into the alveolar ridge area. In many cases the actual size and configuration of the maxilla are satisfactory in terms of height and width of the alveolar ridge area.
However, extension of the maxillary sinuses into the alveolar ridge may prevent placement oi 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. In this technique an opening is made in the lateral aspect uf the maxillary wall, and the sinus lining is carefully elevated from the bony floor of the sinus (Fig. 13-37). Allogeneic bone. autogenous bone, or a combination’ of these materials ‘can be used as a graft source in these areas. The CUfrent method of choice usually incorporates some autoge-” nous bone material in the sinus graft. The graft is allowed
to heal for 3 to 6 months, after which the Iirst stage of implant placement can begin in the usual fashion described in Chapter 14. This procedure can ..be performed 15outpatient surgery and ,docs not affect postoperative
denture wearing .

Maxillary Hydroxyapatite Augmentation

Maxillary Hydroxyapatite Augmentation

HA is readily  eliminates the need for donor-site’ ~lIrgery, and is castly placed in an outpatient setting. H:\ can be used to contour and eliminate minor ridge migration and undercut areas in the maxilla.I\:\ is pla ced into the maxilla in ” tet lmique similar tothat described for mandibular augrncntati, In. In the maxilla”single midline incision is unvually sufficient Ior adequa teaccess to both sides of the m.ixillarv ridge j Fig. 13-36).When access through a single incision is inadequate

FIG. I 3- 35 Interpositional (Le Fort I) augmentation of maxilla. A, Diagrammatic representation of atrophic maxillary alveolar ridge. B,~ugmentation is comp'leted.lJy down-fracturing maxilla and placing mterposttional graft using autogenous iliac crest. C, The maxilla is stabilized using rigid fixation plates.

FIG. I 3- 35 Interpositional (Le Fort I) augmentation of maxilla. A, Diagrammatic
representation of atrophic maxillary alveolar ridge.
B,~ugmentation is comp’leted.lJy down-fracturing maxilla and placing
mterposttional graft using autogenous iliac crest. C, The maxilla
is stabilized using rigid fixation plates.

ri,.:;.E· 30 HA augmentation of maxilla. A, Midline incision and subperiosteal tunnels used to expose areas of maxilla to be augmented. B, Injection of HA material into svbperiosteat tunnels. C, Soft tissue closure.

ri,.:;.E· 30 HA augmentation of maxilla. A, Midline incision and
subperiosteal tunnels used to expose areas of maxilla to be augmented.
B, Injection of HA material into svbperiosteat tunnels. C, Soft
tissue closure.

eral vertical maxillary incisions in the canine and premolar areas can be used to improve visibility and access. Subperiosteal tunnels are created over the crest of the alveolar ridge, and preloaded syringes are inserted into the most posterior aspect of these tunnels. The HA particles are in jected and molded to the desired height and contour, and the incisions are dosed with a horizontal mattress suture. The amount of augmentation possible in the maxilla is sometimes limited by the ability to develop sufficient space for HA particles in the subperiosteal tunnels, Loss of
containment or displacement of the HA particles can result in inadequate ridge form.

Interpositional Bone Grafts

Interpositional Bone Grafts

Maxillary interpositional bone grafting maintains the blood supply to the repositioned portion of the maxilla and generally results in more predictability with less extensive resorption postoperatively. Interpositional bone grafting in the maxilla is indicated in the bone-deficient maxilla, where the palatal vault is found to be adequately formed b ut ridge height is insufficient tparticularlv in the zygomatic buttress and posterior tuberosity areas and when excessive interarch space eXists).cl Anteroposterior and transverse discrepancies between the maxilla and mandible can also be corrected by interposrtlonat bone-grafting techniques (Fig. 13-35). Interpositional grafting techniques provide stable and predictable results by changing the rnax illary posttion ill the vertical, anteroposterior, and transverse directionscine! may eliminate the need for secondary soft ~j sue procedure . Disadvantages of this type of procedure include  the need to harvest bone from an- iliac crest donor site • and possible secondary soft tissue surgery.

Onlay Bone Grafting

Onlay Bone Grafting

autogenous rib was first described by Terry, Albright, and Baker.U Maxillary onlay bone grafttng is indicated primarily when severe resorption of the maxillary alveolus is seen that results in the absence of a clinical alveolar ridge and loss of adequate palatal vault fmlll.22 Maxillary onlay grafting currently -is usually accomplrshed using corticocancellous blocks of iliac crest bone.- The blocks can he secured to the maxilla with small screws, eliminating mobility and decreasing resorption (Fig. 13-34). Cancellous bone is then packed around the grafts to improve contour. Implants can be placed at the time of grafting in some cases, but placement is.

FJG. 13-33-cont'd E, Preoperative radioqraph. F,Postoperative clinical photograph. (Split-thickness skin-grafting procedure has been done after HA augmentation to improve vestibular depth.) G, Postoperative radiograph demonstrating improvement in height of alveolar ridge area.

FJG. 13-33-cont’d E, Preoperative radioqraph. F,Postoperative clinical photograph. (Split-thickness
skin-grafting procedure has been done after HA augmentation to improve vestibular depth.)
G, Postoperative radiograph demonstrating improvement in height of alveolar ridge area.

FIG. 13-34 Iliac crest onlay bone reconstruction of maxilla. A, Diagram of atrophic maxilla. B, Clinical photograph. C, Three seqrnents of bo~e are secured in place. Small defects are filled with cancellous bone. 0, Clinical photograph.

FIG. 13-34 Iliac crest onlay bone reconstruction of maxilla. A, Diagram of atrophic maxilla. B, Clinical
photograph. C, Three seqrnents of bo~e are secured in place. Small defects are filled with cancellous
bone. 0, Clinical photograph.

 

 

 

 

 

 

 

MAXILLARY AUGMENTION

MAXILLARY AUGMENTION

Severe resorption of the maxillary alveolar ridge is  not “as common as mandibular resorption. hen moderate-to-severe maxillary resorption docs occur, the denture-bearing area of the maxilla may allow prosthetic rehabilitation without bony augmentation. In certain cases a severe increase in lnterarch space, loss of patata] vault, interference from the zygomatic buttressarea, and absence of posterior tuberosity notching mav prevent construction of proper dentures, and augmentation must be considered.

Guided Bone Regeneration (Osteopromotion)

Guided Bone Regeneration (Osteopromotion) 

In guided bone regeneration, a membrane (nonresorbable or resorbable) is used to cover an area where bone graft healing or bone regeneration is desired. The concept c’: guided regeneration, or osteo rornotion, is
based o , the ability to exclude undesirable cell types, such a’ epithelial cells or fibroblasts, from the area where bone healing is taking place. .
In 19H2, Nyman 19 described a technique to improve periodontal ligament regeneration using a membrane barrier to exclude undesirable cells from the area where periodontal ligament healing or regeneration was required. Dahlin er al20 showed that bone growth around implants couled be facilitated using a similar technique. By placing a membrane covering over a bone graft,”  aster-growing fibroblasts and epithelial cells can be walled off, allowing bone to grow in a relatively protected environment.Many type~ 01 materials have been used as membrane coverings. Currently, expanded olytetrafluorocthylenc

lilac crest paruculate graft used for auqrnentation of inferior border of mandible. A, Preoperative Panorex of atrophic edentulous mandible. B, Panorex after inferior border grafting with a cadaveric mandibular strut packed with iliac crest particulate bone harvested from the patient. C, Six-month postoperative Panorex showing consolidation and maturation of the gr~ft with increased dimensions .. (Courtesy of Or. Peter Quinn.)

lilac crest paruculate graft used for auqrnentation of inferior border of mandible.
A, Preoperative Panorex of atrophic edentulous mandible. B, Panorex after inferior border grafting
with a cadaveric mandibular strut packed with iliac crest particulate bone harvested from
the patient. C, Six-month postoperative Panorex showing consolidation and maturation of the
gr~ft with increased dimensions .. (Courtesy of Or. Peter Quinn.)

FIG. 13-33 Diagrammatic representation of hydroxyapatite (HA) augmentation. procedure. A, Vertical incisions placed anterior to mental nerve area. Subperiosteal tunnels are then developed in posterior and anterior areas. Retraction sutures are used to elevate margins of incision. 8, Injection of HA into subperiosteal tunnels. C, Soft tissue closure. D, Preoperative clinical photograph .•

FIG. 13-33 Diagrammatic representation of hydroxyapatite
(HA) augmentation. procedure. A, Vertical incisions placed
anterior to mental nerve area. Subperiosteal tunnels are
then developed in posterior and anterior areas. Retraction
sutures are used to elevate margins of incision. 8, Injection
of HA into subperiosteal tunnels. C, Soft tissue closure.
D, Preoperative clinical photograph 

(el’Fl’Lt membrane is the most popular.’ This membrane is not resorbable and must be removed after adequate bone .healing occurs. Resorbable membranes such as homologous grafts and genetically engineered materials such as collagen, eliminate the need for a second surgical procedure for removal. These materials and the concept of guided tissue regeneration arc discussed fully in chapter 14.

Hydroxyapatite Augmentation of the Mandible

Hydroxyapatite Augmentation of the Mandible

The problems associated with bone grafting, including resorption, donor-site morbidity, and the need for hospitalization, have in part been responsibte for the search for an alloplastic material that would function as an adequate graft: material for the atrophic mandible. HA is a dense biocompatible material that can be produced synthetically or obtained from biologic sources such as :”’~’:::. At this time the granular, or particle, form is most commonly used for augmenting alveolar ridge contour
defects. When placed in a subperiosteal environment adjacent to bone, HA bonds physically and chemically to the bone. Although some bony growth may occur adjacent to the particles at the area of the interface,   ,lo:~ic”lly c.u h p.rrtick: appedr~ to Ill’ surrounded in a fibrous tissue capsule, with some infiltration of vascular  tissue throughout the graft material. This fibrous encapsulation of the HA particles appears to occur without
the production of any  ignificant inflammation. IX HA aucmentauon 01 till’ mandible can be performed on an outpatient basis, using local anesthetic combined with conscious sedation techniques. i\. subperiosteal tunnel
techniqu.•  is used, which exposes the entire aspect of . . ..• the mandible in the area to be augmented but carefully avoids the neurovascular bundles, f er the tunnel-is created,   preloaded beveled syringe containing HA is inserted into the most posterior aspect of the tunnel; then the 1-1..\ is injected until the desired contour of the mandible is obtained (Fig, 13-33). Similarly insertion of the Hi\. from each lateral incision area augments the anterior area of the mandible. Some surgeons prefer splints to minimize
I-IA displacement and to improve vestibular form during the postoperative period. The splint, constructed on a cast that’ has been waxed to, the desired contour of the mandible after augmentation, is secured in place with circummandibular sutures for 7 to 10 days. Vestibuloplast~’ and skin grafting can be performed 8 to 12 weeks.after augmentation. During this time the HA granules consolidate and become firmly fixed by connective tissue. _ The advantages of HA augmentation are that donor-site, ”Surgery is eliminated and that most patients can undergo this type of procedure in an outpatient setting. Because HA is nonresorbable, no postoperative loss of the graft augmenting the mandible occurs; vascular tissue ingrowth
around the HA provides an adequate vascular bed for future softtissue grafts, if necessary. The disadvantages of HA are the difficulty sometimes encountered in containing the material within the subperiosteal tunnel and in achieving the adequate contour that is often desirable. Some nerve dysesthesias have also been associated with H augmentation,

Superior Border Augmentation

Superior Border Augmentation

Superior border augmentation with a bone graft is occasionally jndicated when severe resorption of the mandible results in inadequate height and contour and potential risk of fracture or when the treatment plan calls
for placement of implants in areas of insufficient bone  height or width. Neurosensory disturbances from inferior alveolar nerve dehiscence at the location of the mental foramen at the superior aspect of the mandible also can be corrected with this technique (Fig. 13-31). ‘ The use of autogenous corticocancellous blocks of iliac crest bone was described by Thoma and Holland in 195115 for superior border augmentation. However, as much as 70% resorption of iliac crest bone can occur with this technique.l” This large amount. of resorption may be the result of movement of the bone graft segments that were initially wired to the mandible allowtngslight
movement combined with the external rather than internal loads placed on the graft after healing. Currently these blocks of bone’ are frequently secured to the mandible’ with small rigid fixation screws, mini mjzing graft mobility. Tissue-guided regeneration with the use of. a membrane is often combined with the  bony augmentation. In some cases implants can be
placed at the same time the bone graft augmentation is

FIG, 13-30 A, Appearance of maxillary alveolar ridge after removal of teeth. B, Intraseptal removal of bone with rongeur. C, Clear acrylic surgical guide in place. Any areas -that interfere with seating of template or cause blanching of tissue from excess bone or underlying soft tissue should be removed (arrow).

FIG, 13-30 A, Appearance of maxillary alveolar ridge after removal of teeth. B, Intraseptal
removal of bone with rongeur. C, Clear acrylic surgical guide in place. Any areas -that interfere
with seating of template or cause blanching of tissue from excess bone or underlying soft tissue
should be removed (arrow).

FIG. '3-3" Superior border grafting of atrophic mandible. Dia- .grammatic representation of corticocancellous iliac crest blocks con- . toured to adapt to configuration of mandible, then fixated with miniplates and screws

FIG. ‘3-3″ Superior border grafting of atrophic mandible. Dia-
.grammatic representation of corticocancellous iliac crest blocks con-
. toured to adapt to configuration of mandible, then fixated with
miniplates and screws

Inferior Border Augmentation

Sanders and Cox 17 reported the first clinical use of an inferior border technique for augmentation of the atrophic mandible. This technique ts rarely, if ever, used. On occasion the augmentation of mandibular bulk with
inferior grafting is ac complished using iliac crest bone grafts, secured with rigid fixation (Fig. 13-:~2). In rare cases this technique is also combined with immediate placement of implants. Indications for use of this technique, in addition to atrophy-of the alveolar ridge area, included the prevention and management of fractures of the atrophic mandible. However, this technique does not address abnormalities of the denture-bearing areas, such as the increased interarch distance, superior border irregularities, or exposed position of the mental nerve, which result from mandibular atrophy.

MANDIBULAR AUGMENTATION

MANDIBULAR AUGMENTATION

Augmentation grafting adds strength, to an extremely deficient mandible and improves the height and contour of the available bone for implant placement on denture-bearing areas. Sources of graft ma erial include
autogenous or allogeneic bone and alloplastic materials.Historically, autogenous bone has been the most biologically acceptable material used in mandibular augmentation. Disadvantages of the use of autogenous bone
include the need for donor-site surgery and extensive resorption after grafting. The use of allogeneic bone eliminates the need for a second surgical site and has been shown to be somewhat useful in augmenting small areas of concavity in the posterior mandible.!” However, when used for large augmentations, this material often results in dehiscence o f the graft and resorption similar to that of autogenous bone. During the 1980s and early 1990s, HA alloplastic materials became popular for use in bony
augmentation of the maxilla and mandible. The material is readily available, eliminates the need for donor-site Surgery, and has been shown to improve long-term maintenance of height and contour. Several problems, including
tissue dehiscence, migration of the HA, and neurosensory disturbance, have resulted in less frequent use of this material. The increased popularity of implants has  renewed enthusiasm for use of autogenous bone grafts in areas augmented for placement of implants.

OVERDENTURE SURGERY

OVERDENTURE SURGERY

Alveolar bone is maintained primarily in response to  stresses transferred to the bone through the teeth and periodontal ligament during mastication. By maintaing teeth wherever possible, resorption of bone under a prosthetic appliance may be minimized. An overdenture te hnique attempts to maintain teeth in the alveolus by transferring force directly to the bone and improving masticatory function with prosthetic restoration. The presence of teeth may also improve proprioception during function, and special retentive attachments can be. incorporated into the retained teethto imp ove denture retention and stability. Overdentures should be  considered wherever several teeth exist with adequate bone support and when good periodontal health can be maintained and the teeth can be properly restored. Bilateral canines are generally best suited for this type of-heatment. Because this technique also requires endodontic and prosthetic treatment of retained teeth, financial considerations must also be taken into account.A complete discussion of periodontal considerations is – not within- the scope of this chapter; however, it is extremely important to evaluate any potentially retained teeth before preparing the ‘patient for an overdenture. Adequate clinical and radio graphic evaluation of   teeth should be completed, including a  cxarnination,  evaluation of pocket depth around the tu’th.’ and evaluation ofthe attached gingiva .