Category Archives: Contemporary Implant Dentistry Edwin

SPECIAL SITUATIONS

SPECIAL SITUATIONS

Postextractlon Placement of Implants

When implant placeentis planned before extraction of the tooth, consideration should be given to the most desirable time, for implant placement. The implant may be placed immediately (l.e., at the time of extraction), early (Le., 2 months after extraction), or late (Le., more than 6 months after extraction). Each of these times has its indications, advantages, and disadvantages . Immediate placement allows the overa l lshortest healing time and combines the tooth extraction with the surgical

FIG, 14-63 A, Pneumatized sinus. B to D, Gradual enlargement of the osteotomy site for the implant results in compaction of the bone surrounding the implant site and also pushes bone ahead of the implant, indirectlY,elevating the sinus floor and allowing space for a longer implant.

FIG, 14-63 A, Pneumatized sinus. B to D, Gradual enlargement of the osteotomy site for the implant
results in compaction of the bone surrounding the implant site and also pushes bone ahead of the
implant, indirectlY,elevating the sinus floor and allowing space for a longer implant.

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FIG. 14-64 Direct sinus lift procedure.

FIG. 14-64 Direct sinus lift procedure.

·FIG. 14-65 Implants placed in fresh extraction sockets must ha\ e 4 mm of precise fit along apical aspect of implant. They should be countersunk 2 mm, and gap between sides of extraction socket and implant should be less than 1 mm. If gap is greater than 1 mm, grifting with demineralized allogeneic bone should be con~idered.

·FIG. 14-65 Implants placed in fresh extraction sockets must h 4 mm of precise fit along
apical aspect of implant. They should be countersunk 2 mm, and gap between sides of
extraction socket and implant should be less than 1 mm. If gap is greater than 1 mm, grifting
with demineralized allogeneic bone should be con~idered.

implant placement. Immediate placement can be considered if the tooth to be removed is not infected and can be removed without the loss of -alveolar bone. Once the tooth Is removed the implant is p aced at least 4 mm aptcal
to the apex of the tooth (Fig. 14-65). The implant should be countersunk 2 mm below the height of the crestal bone to allow for resorption of the bone secondary to extraction. The gap between the implant and the residual tooth socket must be evaluated and managed according to its ‘size. If the gap is less than 1 mm, no treatment modification is needed. If the gap.is greater than 1 mm, the same type of guided bone regeneration may be necessary. After implant placement, every effort should be made
to achieve   primary soft tissue closure. If this is not pos- . sible, a resorbable collagen pellet may be placed over the implant and held in place with a flgure-elght suture. The time for integration should be extended by 1 or 2 months. Even if the extraction site meets the requirements for
immediate imlant placement, it may be desirable to wait. If the socket is reconstructed with a graft, as little as 2 months is an adequate waiting period before implant placement. During this time the’ overlying soft tissue will heal and primary closure will be easier at the time of implant placement. This is generally long enough to allow remodeling of the socket and, in the case of multirooted teeth, some filling of the socket with bone. In this situation implants areplaced using the same technique described for routine implant placement. The bone in the area of surgery will be softer but generally will allow preparation of the  implant recipient site with little modification. No increase in integration time is generally necessary in this situation. If teeth have been removed longer than 6 months, implant
placement should proceed with no modification in technique.

 

 

 

 

 

 

 

Transantral Grafting (Sinus Lift)

Transantral Grafting (Sinus Lift)

After tooth loss, alveolar resorption occurs. In the posterior -rnaxilla, crestal bone resorption Js also accompanied by sinus pneumatization. In situations wHere inadequate bone existsto place implants of appropriatelength, sinus floor.augmentation can be performed. Thi, can be dcne-indirectly 0through the implant osteotomy site or directly-by an approach through the lateral wall of the maxillary sinus. ‘ hen only a few millijneters of augmentation is needed
in copjunction with simultaneous impla.,ot placement, indirect sinus lift is effective. This procedure relies on the lack of density found in maxillary cancellous bone. The initial drill-is used to locate the angulation and position of the planned implant. The depth is drilled just short of the sinus floor. Osteotoines are then used to progressively enlarge the site. The osteotome is cupped on the end and compresses the walls of the osteotomy site: it alsoscrapes bone from the sides of the wall, pushing it ahead. The bone· of the sinus floor is pushed.upward elevating the’ sinus rrterribrane and depositing the bone from the .lateral wall of the osteotomy into the sinus below the membrane (Fig. 14-63). If needed, additional graft material
can be introduc ed through the implant site. Undetected’ per oration may occur with this tech- ‘niqiie. :rhi’s procedure is only possible when a few mil- Iimeters of bone’ is needed for an implant that has ade, quate primary stability in native bone. . If several implants are to be placed or more than
2 or 3 mm of augmentatio  is needed, a direct approach is required .. A window is created In-the lateral wa11 of the sinus, and the sinus membrane is elevated and the floor is grafted to increase vertical bone height (Fig. 14-64). Implants may be placed simultaneously With the grafting procedure if adequate native bone is present Jor primary implant stability. This is usually defined a.s4 mm or more of bone. If less than 4.nun of bone Isavailable.jhe procedure should be staged with initial grafting alone, after
. which the graft Is.consolidated and the implant- placed .. Transaritral grafting (i.e., sinus lift) procedures can be .per- . formed in an outpatient setting using autogenous bone,allogeneic bone, or bone substitutes.

FIG. 14-62 A,·Onlay grafts were' attempted to restore this 'Iarge anterior maxillary defect " resulting from trauma. These grafts failed, "and a large defect persists, 8, Typical device for alve- _ alar distraction. The bone remains ped~ed to the palatal tissue ana can be.transported to a more favorable position slowly as bo.ne fills in above the mobilized segment.

FIG. 14-62 A,·Onlay grafts were’ attempted to restore this ‘Iarge anterior maxillary defect
” resulting from trauma. These grafts failed, “and a large defect persists, 8, Typical device for alve-
_ alar distraction. The bone remains ped~ed to the palatal tissue ana can be.transported to a
more favorable position slowly as bone fills in above the mobilized segment.

Success is similar for all these materials. Autogenous  .bone requires less time than allogeneic or xenogeneic bone to consolidate (4 to 6 months versus 7 to 12 months). The available bone to support the implant can be significantly improved with these techniques. Patients who smoke have a significant increased failure rate. Some authors suggest that smoking [s a contraindication to sinus lift. In addition, a much higher. incidence of infection after this pr-ocedure is found. than with other implant surgery. Antiblotlc prophylaxis is paramount. .  Patientsmust also refrain ‘from wearing prosthesis. over the surgical area for a  week.

 

 

 

 

 

Alveolar Distraction

Alveolar Distraction

011 grafting techniques are compromised when inadequate soft tissue is present: This is particularly problematic in the anterior maxilla when vertical hard and soft tissue defects e~ist after trauma or treatment of patholo

FIG. 14-60 Graft sites from the genial region or tram the buccal shelf.

FIG. 14-60 Graft sites from the genial region or tram the buccal shelf.

gy. Tightly bound tissue in this area makes primary closure very difficult. Distraction osteogenesis techniques take advantage of the development of bone that results –  when an osteotomized segment of bone is slowly moved,
allowing new bone formation within the gap. This technique was initially used to lengthen long bones, but the  principles have been applied to the jaws and to alveolar bone. The technique has the disadvantage of increased

 

 

 

Block Bone Grafting

Block Bone Grafting

Guided bone regeneration is most often used for lateral ridge augmentation. Some authors have described vertical augmentation, but it is less predictable.
Corticocancellous bone grafts are an a lternative to guided bone regeneration techniques. Bone can be harvested  from the genial region, mandibular all}us, or iliac crest and used to augment lateral or vertical height of the atrophic ridge (Fig. 14-60). The defect is approached and  prepared for grafting by perforating the cortical bone and creating a site to receive the graft. The corticocancellous block is harvested and trimmed to fit into the defect. Stabilization of the graft and primary closure is paramount. After 4 to 6 months of healing,

Block Bone Grafting

Block Bone Grafting

Guided bone regeneration is most often used for lateral ridge augmentation. Some authors have described vertical augmentation, but it is less predictable.
Corticocancellous bone grafts are an alternative to guided bone regeneration techniques. Bone can be harvested from the genial region, mandibular rall}us, or iliac crest and used to augment lateral or vertical height of the atrophic ridge (Fig. 14-60). The defect is approached and prepared for grafting by perforating the cortical bone and ~ creating a site to receive the graft. The corticocancellous block is harvested and trimmed to fit into the defect. Stabilization of the graft and primary closure is paramount. After 4 to 6 months of healing, the implant surgery can jJe accomplished (Fig. 14-61).

ADVANCED SURGICALTECHNIQUES

ADVANCED SURGICAL TECHNIQUES

Guided Bone Regeneration

Guided bone regeneration is a process that allows bone growth while retarding the ingrowth of fibrous connec- Itive tissue .and epithelium. It is well recognized that most r bone defects will regenerate with new bone if the invao sion.of connective tissue fr.om adjacent soft tissue can be prevented. Guided bone regeneration uses a barrier that is placed over the bone defect and prevents fibrous tissue ingrowth while the bone underlying the barrier has time . to grow and fill the defect (Fig. 14-59). This technique is particularly useful in the treatment of bccal dehiscence,
where labiobuccal augmentation of bone is required Guided bone regeneration can be performed- simultaneously with implant placement or before stage L A variety of materials may serve as barriers to fibrous tissue
ingrowth. Ideal characteristics of a membrane are outlined in Box 14-7. Expanded p (Gore- Tex) is the most extensively tested material. Resorbable . materials are also now available, eliminating the necessityof removal.

 

FIG. 14-59 Various applications of guided bone regeneration. A, membrane and "filler material" such as allogeneic bone is used to augment the ridge. B, Same as in A except that an implant is placed simultaneously. C, The membrane is supported by screws that preserve the space beneath the graft to allow bone fill.

FIG. 14-59 Various applications of guided bone regeneration. A, membrane and “filler material”
such as allogeneic bone is used to augment the ridge. B, Same as in A except that an implant is placed
simultaneously. C, The membrane is supported by screws that preserve the space beneath the graft to
allow bone fill.

BOX 14-7

Characteristics of Ideal Membrane

• Effective
• Ease of handling
• Inexpensive
• Resorbable
• Tolerates exposure

 

 

 

 

 

 

Failing Implant

Failing Implant

Implant failure occurs at three distinct times: (1) at the time of (or shortly after) stage II surgery, (2) approximately 18 months after stage II surgery, and (3) more than 18 months after stage JI surgery. A few implantswlll fail to integrate. This failure will be identified at the time of (or shortly after) stage II surgery. Failure in this period may be related to a variety of factors.
Overheating of the bone during placement or failure to achieve a precise implant fit with primary stability may lead to failure of integration. Postoperative infection, excessive pressure on the integrating implant (with
movement of the implant), or wound-healing problems may also jeopardize implant integration. After loadingwith a prosthesis, bone loss will occur for approximately 18 months after which time a steady state will be achieved. During this 18-month period, additionalimplant failure may occur. Failure in this period is often associated with excessive biomechanical forces on the
implant or compromised periimplant soft tissue health resulting from lack of attached tissue, poor hygiene, orboth. Smoking is also associated with increased failure in this period and later periods. Late failure (i.e., more than HLmontl}s after placement of the prosthesis) may also occur. This is rare, and frequently the cause is not identifiable. In general, these implants are identified as “ailing” during routine recall. Progressive bone loss in spite of rigorous hygiene measures is often seen. A combined prosthodohtic and surgical intervention can often restore health to these ailing implants. Once periimplant bone loss has been identified, effortsshould initially be focused on optimizing hygiene. This may even require removal of the prosthesis to facilitate access. If bone loss is severe or progressive, surgical intervention
js necessary. The implant must be exposed surgically and all soft tissue adjacent to the “implant surface removed. The surface of the implant is then cleaned with hydrogen peroxide, after which citric acid is used.  etracycline
powder is placed along the implant surface and into the bony defect, and the defect reconstructed with a graft. Healing for a minimum of4 months is allowed, after which the implant is uncovered and the prosthesis replaced.

COMPLICATIONS

COMPLICATIONS

Potential- complications include improper angulation or position of the implants; perforation of the inferior border, the maxillary sinus, or the inferior alveolar canal; dehiscence of the buccocortical ‘or iinguocortical plate; mandibular fracture; and soft tissue wound dehiscence. Variation in the position or angulation of the implant results when the anatomy found at surgery requires implant placement different from that planned preoperatively. This should be avoided by grafting to allow  implant placement in the desired location and angle. In the event that ideal angulation has not been achieved, a variety of prosthodontic attachments are available to salvage implants that have nonideal angulation. Sinus perforation occurring during drilling for implant placement is unlikely to cause serious sequelae. Shorter implant length than ‘planned may be necessary to prevent  the implant from extending too far into the sinus.
Usually the resistance provided by the cortical bone of the mailIary sinus-floor is encountered before a perforation results and can serve as an indicator that maximum depth has been reached. If perforation does occur and the implant is placed only a short distance into the maxillary .. sinus, a problem is not likely (Fig. 14-55). Similar guidelines exist for perforation of the inferior border of the.  mandible. The apical portion of the implant should be  within the cor.tical bone of the inferior border. Perforation’ of the interior alveolar canal is a serious problem. Local infiltration over the. bone crest rather than inferior alveolar nerve block may facilitate identification of this at surgery because the patient-will be adequately
anesthetized f or implant placement but feel sharp pain if the canal is perforated. Perforation  may also be accompanied by sudden increased·
bleeding. If this occurs an implant shorter than planned should be used. If the implant appears to extend into the inferior alveolar canal on the postoperative radio graphs (Fig. 14-56), the implant should be immediately removedand a shorter implant placed. If no indication of perforation
exists and no radiographic evidence of violation of the canal is noted, patients maystill have postoperative00  neurosensory alteration. This may be from trac.tion on the mental nerve, from direct in jury during implant
placement, or from etraosseous hematoma or s.oft tissue swelling. These patients should be followe-d closely. Deficits of this nature will generally resolve wit.h time but may require surgical intervention if they persist and are bothersome to the patient. . _ Perforation of the buccocortical or linguocorticalplates may occur when resorption has re sulted in a thin
ridge along the planried implant site. A simple solution is to countersink the implant until tt re depth of the implant recipient site is adequate for t’ he length of the implant. This may leave excess bone h eight on the lin-·
gual, mesialnd distal surfaces. At the time ofuncovering there may be bone growth over the implant that requires removal. If the sharp crest i s generalized and several implants are to be placed, the entire crest can be
reduced down to a suitable width. If a dehiscence does occur, it should be evaluated and a de cision made regarding treatment. A small, 1- to 2″mm loony dehiscence on the buccal aspect of an implant will generally require no additional treatment. Larger defect .s, particularly if the implant is short, may cornprom.lse stability.’ If this results, the defect can be grafted (‘fig. 14-57). This technique is more fully discussed in’ th.e section on advanced
surgical techniques. An unusual complication of implant placement in the
. mandible is mandibular fracture (Fig. 14-58). This is most likely when the mandible is very atrophic, when preexistingmetabolic disease (e.g., osteoporosis) Is seen, orwhen the patient has a history of postoperative trauma.Failure to tap threaded implants in very dense mandibularbone may also be associated with fracture, Managementmay require bone graftlng to. increase the bonemass of the mandible.Soft tissue wound dehiscence may occur, which illlowspart of the imptant to become exposed, If this occurs noattempt should be made to resuture the wound, because
the only result will be increased wound dehiscence

FIG. 14-56 A, Radi09ra'ph taken: imm~iately after place~ent of, two implants in right posterior mandible.Jrnptants appear tQ. violate s·uperior border of inferior !llveolar carial (dotted line). 8, Implants were replaced and are above canal (dott~ ;ine): Patient had no permanent deficit.

FIG. 14-56 A, Radi09ra’ph taken: imm~iately after place~ent of, two implants in right posterior
mandible.Jrnptants appear tQ. violate s·uperior border of inferior !llveolar carial (dotted line). 8, Implants
were replaced and are above canal (dott~ ;ine): Patient had no permanent deficit.

FIG. 14-~7 In an ideal situation (A), adequate bone on buccolinguc11areas for implant placement e~ists. This may not occur when there has been resorption of buccal bone (B). Acceptable ways to handl~ this include removal of sharp crest to level of adequate width for implant or placement of bone graft over buccal dehiscence that results.

FIG. 14-~7 In an ideal situation (A), adequate bone on buccolinguc11areas for implant placement
e~ists. This may not occur when there has been resorption of buccal bone (B). Acceptable ways to handl~
this include removal of sharp crest to level of adequate width for implant or placement of bone
graft over buccal dehiscence that results.

fiG. 14-58 Implants may weaken mandible and lead to fracture. This is most common in severely atrophic mandible and after traus:na.

fiG. 14-58 Implants may weaken mandible and lead to fracture. This is most common in
severely atrophic mandible and after traus:na.

Chlorhexidine rinses should be used until soft tissue healing has occurred. If the tissue is healthy but the implant  remains exposed, a soft toothbrush dipped in chlorhexidineshould be used to keep the implant clean  hroughout the Iategration period. This should result in no increase implant failure, because single-stage implants are purposely left exposed throughout osseointe gration and have comparable success as two-stage systems

 

 

 

 

 

 

 

 

 

Uncovering

Uncovering

The length of time necessary to achieve integration varies from site to site and may require modification based on the particular situation. Successful loading with shorter integration times has been reported when various protocols
are followed  (see Table 14-2 for conventionally accepted times for integration based on historical experience, which should serve as a referece point). Although shorter times may be possible, longer times may be required if the bone quality at surgery was poor or if there  was a question regarding ‘the adequacy of bone-to- -implant interface at the time of placement. In a single-stage system, the implant remains exposed after surgery artd throughout the healing phase. After appropriate integration time, restoration can proceed. In a two-stage system, the implant must be uncovered

FIG. 14-52 Tissue punch removes small plug of tissue overlying implant and allows access for attachment of superstructure.,

FIG. 14-52 Tissue punch removes small plug of tissue overlying implant and allows access for attachment
of superstructure.,

BOX 14-6

Indications for Various Uncovering Techniques

TIssue Pundt
Requirements: .
Adequate attached tissue
Implant can be palpated
Advantages:
least traumatic
Periosteum not reflected-less bone resorption
Earl}timpressions’ are possible
Disadvantages:
Sacrifice attached tissue
Unable to visualize bone
.Unable to visualize implant and superstructure interface
Crestal Incision
Requirements:
Adequate attached tissue
Advantages:. . .
Does not require implants to be palpable
Easy access
Minimal trauma
Able to visualize bone
Able to visualize implant and superstructure interface
Disadvantages:
Periosteum reflected-may lead to bone loss
Apically Repositioned Flap
Advantages:
Improve vestibular depth, attached tissue
Disadvantages:
Longer healing time
Bone loss as a result of reflection of periosteum
Technically more difficult

before restoration. The goals of surgical uncovering are to  accurately attach the abutment to the implant, preserve attached tissue, and recontour and thin tissue or add form and thickness to existing tissue. This may be accomplished by one of the following general techniques: the tissue punch, crestal incision, flap repositioning, or soft tissue grafting. Each has its own advantages . and indications (Box 14-6).  he simplest method of implant uncovering is the tissue punch (Fig. 14-52). This method of  reccovering is easy to perform, only minimally disturbs the tissue surrounding the implant, and produces minimal patient discomfort.
To. use this t echnique, the implant must be locatedwith certainty below the tissue. Use of the punch is contraindicated if inadequate attached tissue will remain after the punch is used. The punch also has the slight disadvantage
of not allowing visualization of the bone. If a graft was placed or if there was some question regarding the relationship between the marginal bone and .the implant, this technique would not allow assessment at the time of uncovering nor could nonresorbable guided tissue regeneration  embranes be removed. This technique also makes visualization of the abutment-toimplant body interface difficult. The operator must rely on’ tactile sense to determine if the abutment is completely seated on the implant body.
If the implants cannot be palpated or the cl inician needs to visualize the marginal bone, a crestal incision over the implant is indicated. If sufficient attached tissue is found, a punch or scissors can be used to contour the
edge of the flap to conform to the implant before wound closure. This technique will also heal rapidly because primary closure exists. This technique also requires adequate attached tissue. . ff attached tissue surrounding the implant is limited or inadequate, an apically repositioned flap is the uncovering method of choice. A crestal incision developed in a
supraperiostcal plane is performed to develop a splitthickness flap. The flap is then sutured over the facial surface at a more apical level. Healing occurs by secondary intention. This technique requires the longest healing

FIG. 14-53 A, Pedicled connective tissue graft from the palate can be used to augment the labial soft tissue contour. 8, Free connective tissue graft can also be used to accomplish the same thing ..

FIG. 14-53 A, Pedicled connective tissue graft from the palate can be used to augment the
labial soft tissue contour. 8, Free connective tissue graft can also be used to accomplish the
same thing ..

time and is more jinful. It preserves and increases the  amount of .lttache~oft tissue, but does not improve tis-  .sue thickness. In some situation She bulk of soft tissue is not adequate  to produce proper Ctltour around the implant. This is especially a problem nthe anterior maxilla where, despite adequate osseous conhr and proper implant placement, a localized depression, the facial margin of the crown is found that will compr<nise esthetics. In this situation a pedicled or free connecva tissue graft is an effective way to restore soft tissue fOfIiaround the imp ant (Fig. 14-53). These procedures allow nnor changes in the tissue height around the implant crovi but cannot substitute for adequate osseous form thatnust always be maintained (or  reestablished first). In situations in whic the overlying tissue is very thick, it may be necessar; to recontour tissue. A carbon dioxide laser or electro  a~ry is quite effective. Laser or bipolar cautery poses less 15kof damage to jhe implant or bone than  onventional’lonopolar cautery.After the implant is exposed the implant abutment is placed. Two approaches can be used to do this: One approach. is to place the abutment that the restorative  dentist will use in the restoration. This is effective in the’ mandible and posterior maxilla where esthetics is ‘of less  concern. The other technique is to place a temporary healing abutment that will remain until the tissue heals and will then be discarded and replaced by an abutment. This may be a factory or custom-made abutment. A custom abutment will help contour soft tissue for better esthetic results. A custom abutment is made from an index of implant position recorded at the time of placement. When the abutment is placed, it is important that it be completely seated on the implant body without gaps or intervening soft or hard tissue. In systems that have antirotational facets built into the implant, these must be aligned to allow complete seating of the abutment. The abutment-to-implant jnterface should be evaluated radi
ographically immediately after uncovering. If a gap i present, the abutment must be repositioned (Fig..14-54)

FIG. 14-54 Radiographs should be taken after attachment of abutments and before impressions. This radiograph shows that abutments are not properly seated on implant body, which could lead to error In fabrication of' implant prosthesis if not properly seated _ before impression.

FIG. 14-54 Radiographs should be taken after attachment of abutments
and before impressions. This radiograph shows that abutments
are not properly seated on implant body, which could lead to
error In fabrication of’ implant prosthesis if not properly seated
_ before impression.

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Postoperative Care

Postoperative Care

A radiograph should, be taken postoperatively to evaluate the positron of the implant in relation to adjacent struc- o. tures, such as the’ snus and inferior alveolar canal, and relative to other implants. Patients should be provided analgesics. Mild-to-moderate strength analgesics are usually sufficient. Rarely will ‘ potent oral analgesics be required. Patients should also be placed on 0.12% chlorhexidtne gluconate rinses (Peridex) for;l weeks after surgery to help keep bacterial populations at a minimum during healing. The patient is evaluated on a weekly basis until soft tissue wound healing is complete

(approximately 2 to 3 weeks). If the patient wears a denture ‘over the area of implant placement, the denture can be relined with a-soft liner after I, week and may be worn.