Jan Lindhe. Clinical Periodontology

Подождите немного. Документ загружается.

CHAPTER 39

Procedures Used to Augment

the Deficient Alveolar Ridge

MASSIMO SIMION

General considerations

Case reports

Alveolar ridge augmentation for single tooth

restoration in the anterior maxilla

Alveolar

ridge augmentation for implant

restoration in

the anterior maxilla

Alveolar ridge augmentation for implant

restoration

of multiple adjacent maxillary teeth Vertical ridge

augmentation in the anterior area of

the mandible

Vertical ridge augmentation to allow implant

placement in the posterior segments of the

mandible

A variety of surgical techniques used for horizontal

and vertical ridge augmentation have been described

by different authors (e.g. Buser et al. 1990, 1993, 1995,

1996, Nevins & Mellonig 1992, 1994, Mellonig & Tri-

plett 1993, Lang et al. 1994, Rominger & Triplett 1994,

Simion et al. 1994, 1998, Tinti et al. 1996, Tinti &

Parma-Benfenati 1998). Such procedures often include

the use of autogenous bone grafts or grafts including

different biomaterials as well as the placement of bar-

rier membranes (guided bone regeneration (GBR), see

Chapter 38). In the present chapter, ridge augmenta-

tion techniques will be described that can be per-

formed either before or in combination with implant

placement and that include the use of autogenous

bone grafts.

GENERAL CONSIDERATIONS

All ridge augmentation procedures should be per-

formed in a proper surgical setting and in patients

with a dentition free of signs of destructive periodon-

titis. Before the surgical session, the perioral skin must

be cleaned with the use of a disinfectant. The patient

must rinse his or her mouth for 2 minutes with a 0.12

0.2% solution of chlorhexidine gluconat. The patient

is subsequently covered with sterile sheets to mini-

mize bacterial contamination from extraoral sites. The

surgical procedure is in most cases performed on a

lightly sedated patient and under local anesthesia.

Flap design

A full thickness crestal incision is placed within the

keratinized mucosa of the edentulous ridge. In a par-

tially dentate patient the crestal incision is extended

into an intrasulcular incision — mesially and/or dis-

tally — to involve one or two adjacent teeth. Vertical

releasing incisions are made at the mesial and distal

ends of the crestal incision. In order to get proper

access to the surgical site the releasing incisions are

frequently made in buccal as well as in lingual (pala-

tal) direction.

Initial preparation of the recipient site

A meticulous preparation of the recipient site is crucial

for the successful outcome of a ridge augmentation

procedure. Thus, following placement of the incisions,

the buccal and palatal (lingual) flaps are reflected with

the use of an elevator, to allow a proper exposure of

the surgical site. During flap elevation care must be

taken not to damage the palatine artery, and the men

tal nerve in patients with a severely reabsorbed max-

illa and/or mandible. Further, the soft tissue flaps

must be handled gently to minimize trauma and to

avoid perforations and lacerations.

Once exposed, the cortical bone at the recipient site

is curetted with a chisel to remove all remnants of

granulation tissue and portions of adherent pe-

riosteum.

898 • CHAPTER 39

Fig. 39-1. A full thickness flap was elevated in the ra

mus of the mandible. The osteotomy was performed

with the use of trephines.

Positioning of the barrier membrane

The barrier membrane most frequently used in ridge

augmentation procedures is made of expanded

polytetrafluoroethylene (e-PTFE; Gore-Tex, W.L. Gore

Ass., Flagstaff, AZ, US) and often the titanium rein-

forced variety of the e-PTFE membrane (TR GTAM;

Gore-Tex, W.L. Gore Ass., Flagstaff, AZ, USA) is

placed to obtain optimal stability of the wound in the

recipient site.

Mini-screws made of stainless steel (or titanium)

are often used to support the membrane in the center

of the defect. The mini-screws are, thus, positioned in

the recipient site and left to protrude from the bone

surface at the intended height of the new bone. As an

alternative to the use of mini-screws, a block of auto-

genous bone can be placed to stabilize the membrane.

The bone block must be firmly anchored to the bone

of the recipient site with fixation screws.

Before the placement of graft material, the cortical

bone of the recipent site must be perforated with a

round bur to expose the cancellous bone and induce a

bleeding hard tissue surface (Rompen et al. 1999).

When a titanium reinforced e-PTFE membrane is

used, the barrier is adjusted with the use of pliers and

adapted to the intended shape of the augmented

ridge. The membrane is trimmed with scissors and

adjusted to extend at least 4-5 mm beyond the margins

of the defect.

Once positioned at the surgical site, the membrane

is fixed to the

lingual/palatal

aspect of the bone crest

with mini-screws. This will allow the graft to be placed

in the recipient site from a buccal direction.

Fig. 39-2. The bone samples were collected with a Molt

curette.

Preparation of the donor site

Both

extraoral

and

intraoral

sites have been proposed

as possible donor sites for the harvesting of auto-

genous bone.

The use of

extraoral

sites, including the iliac crest,

the tibia and the calvaria, allows the harvesting of

large volumes of bone. The use of such donor sites,

however, (1) increases the morbidity associated with

the procedure, and (2) requires general anesthesia and

often the hospitalization of the patient

The most frequently used

intraoral

donor sites in-

clude:

the ramus (the retromolar region)

the symphysis of the mandible.

Before bone is harvested, a comprehensive clinical

and radiographic examination (a panoramic radio-

graph is generally, but not always, sufficient) of the

intraoral donor site must be performed. In this exami

nation the following issues must be considered:

the position of the alveolar nerve in relation to the

bone crest

the position of the mental foramen in relation to an

obvious landmark (e.g. a neighboring tooth)

the length of the roots and the position of the apices

of the mandibular incisors in relation to the lower

border of the mandible

the volume of bone that can be harvested.

Surgical procedure in the region of the ramus

Bone collection from the mandibular ramus is nor-

mally performed only when the third molar is missing

PROCEDURES USED TO AUGMENT THE DEFICIENT ALVEOLAR RIDGE •

and when only a limited amount of bone is required

graft the recipient site.

A crestal incision is made. The incision should start

about 2-3 mm distal of the second molar and be ex-

tended in distal and lateral direction following the

lateral margin of the ramus. A vertical releasing inci-

sion is made at the mesial aspect of the crestal incision.

After the elevation of a full thickness flap, the osteo-

tomy can be accomplished with the use of trephines

thin carbide burs. Bone harvesting must be carried out

in a gentle and careful manner and during irriga

tion

of the surgical site with sterile saline (Figs. 39-1,

39-2).

The dimension (amount) of the bone graft that

can be

harvested is dependent on (1) the buccal-lin

gual

dimension of the ramus, and (2) the position of the

inferior alveolar nerve. Thus, at least 3 mm of intact

bone must remain over the alveolar nerve to

avoid

neurological complications. It is also essential

not to

penetrate the lingual wall of the ramus region

and

thereby sever blood vessels in this region.

When a particulate bone graft is harvested, the

round osteotomies — prepared with a trephine —

should overlap in order to reduce the size of each

individual hard tissue block, and to facilitate their

collection and grinding. After the bone collection pro-

cedure is completed, the flaps are replaced and closed

with interrupted sutures.

Surgical procedure in the region of the

symphysis of the mandible

An incision is placed about 10 mm below the muco-

gingival junction and is extended between the distal

aspect of the two mandibular canines. A full thickness

flap is elevated with a periosteal elevator and is re-

flected from the incision line to the inferior border of

the mandible.

When the intention is to prepare a particulate bone

graft, the osteotomy can be accomplished with me-

dium-sized trephines (8 mm diameter). During bone

sampling the surgical site is irrigated with saline. The

circular osteotomy cuts should overlap to facilitate the

removal of the bone tissue (see above). The depth of

each cut (<— 5-6 mm) must consistently be related to the

buccal-lingual dimension of the donor site (Figs. 39-3,

39-4). The apical limit of the bone harvesting is located

5 mm coronal to the inferior border of the chin. The

coronal limit of the osteotomy is 5 mm apical of the

apex of the anterior teeth, and the lateral limit is 5 mm

mesial to the mental foramen (Hunt & Jovanovic

1999). The bone harvesting is normally made with a

curette. The small hard tissue portions are subdivided

into small bone chips.

When the intention is to harvest a block of bone, a

bone saw can be used to prepare a rectangular shaped

graft of desired dimensions (Figs. 39-5, 39-6).

Before wound closure, a collagen sponge is placed

as hemostatic agent in the donor site. This sponge will

reduce postoperatory swelling and hematoma forma-

Fig. 39-3. Round osteotomies were made with the use

of an 8 mm diameter trephine. The cuts overlapped

and reached a depth of 5-6 mm.

Fig. 39-4. The bone samples were removed and the can

cellous bone was collected with the use of a surgical

spoon.

Fig. 39-5. A rectangular cut was performed with a bone

saw to collect a large bone block.

Fig. 39-6. The bone block was removed and additional

round cuts were prepared with the trephine. The round

bone samples will be ground with the use of a bone

mill to obtain bone chips.

900 • CHAPTER 39

Fig. 39-7. (a) 39-year-old patient exhibiting an implant-supported restoration of tooth 21. The esthetic appearance

was compromised by the

overcontoured" crown. (b) Palatal aspect of the same crown.

tion. The closure of the flaps includes a two-layer

suturing technique, one internal and one external su-

ture. For the internal suture a resorbable suture mate

rial is used. The internal suture often has the design of

a horizontal mattress and is intended to close the

periosteum and the severed muscles. For the external

suture, that is intended for closure of the incision

wounds, a non-resorbable material is used. A continu

ous or an interrupted suturing technique may be

adopted.

During the immediate post-operative period (10

days) most patients will experience some swelling and

discoloration of the chin area. Paresthesia of the lower

anterior tooth region can persist for periods exceeding

6 months.

Positioning of the bone graft in the recipient

site

The barrier membrane is first anchored to the lingual

bone wall of the defect with mini-screws. After the

harvesting of the small bone blocks and the prepara-

tion of bone chips (particulated graft), the graft parti-

cles are packed on the perforated hard tissue surface

of the bone crest of the recipient site. The membrane

is subsequently adjusted to cover the graft and is

finally anchored to the buccal bone wall with mini-

screws placed at the mesiobuccal and distobuccal

rims. This will provide optimal stability of the mem-

brane and ideal protection of the grafts.

In regions where the recipient site is located close

to a natural tooth, a 2 mm wide zone of crestal bone

next to the tooth must be left uncovered by the mem-

brane so that the graft and the membrane will not

interfere with the periodontal tissues of the natural

tooth.

Closure of the recipient site

Releasing incision

Before the wound is closed, a releasing incision must

be made in the periosteum at the base of the buccal

flap (sometimes also of the lingual/palatal flap) to

facilitate soft tissue management and to achieve a

tension-free soft tissue adaptation. The periosteal in-

cision must join the vertical releasing incisions at the

mesial and distal margins of the flap. Particular atten

tion must be paid when such releasing incisions are

placed in the lower jaw in order to avoid damage of

the

inferior alveolar nerve at its exit from the mental

foramen. Moreover, the incisions at the lingual aspect

of the mandible must be placed so as to avoid damage

of the vascular plexa at the floor of the mouth.

Suturing

Wound closure is often accomplished with horizontal

mattress sutures, alternated with interrupted sutures.

Horizontal mattress sutures are applied to achieve

proper flap position. Interrupted sutures are placed

between the mattress sutures and to close the vertical

releasing incisions.

Postoperative care

After the completion of the procedure, the patient

should receive an antibiotic to prevent infection and

an anti-inflammatory agent to reduce edema and

swelling, for a period of about 1 week.

Chemical plaque control including the use of chlor-

hexidine mouth rinses (0.12% solution twice a day) is

instituted for 2 weeks. The sutures are removed after

12-15 days. The e-PTFE membrane is usually removed

after 6 months of healing. Implants may then be

placed in the augmented ridge, according to direc-

tions provided in the manual for the different implant

systems used.

PROCEDURES USED TO AUGMENT THE DEFICIENT ALVEOLAR RIDGE • 901

CASE REPORTS

Patient 1 - Alveolar ridge augmentation for

single tooth restoration in the anterior

maxilla

The 39-year-old man expressed concern about the

esthetic outcome of an implant-supported restoration

that had been placed in the maxillary left central inci-

sor region. The patient also complained about the

bulky palatal surface of the same restoration (Fig.

39-

7a,b). The patient was in good general health and was

a non-smoker.

Initial examination

The patient's natural dentition was in good condition

and he had a comparatively good oral hygiene status.

Tooth 21 presented with an implant-supported crown

made of porcelain fused to metal that was overcon-

toured both at its buccal and lingual aspects (Fig. 39-8).

The peri-implant mucosa exhibited signs of inflam-

mation.

The reason why the restoration had been overcon-

toured by the prosthodontist was, most likely, the

improper position of the implant in the ridge between

the natural teeth. In fact, during surgery the implant

had been placed too far palatally as compared to the

position of the adjacent teeth. The gingiva at the buccal

aspect of tooth 11 and tooth 22 exhibited modest re-

cession (Fig. 39-7a).

Treatment planning

During treatment planning different options were

considered:

removal of the implant and placement of a conven-

tional three-unit bridge

placement of a Maryland bridge restoration

removal of the implant, reconstruction of the soft

and hard tissues at site 21 and subsequently

de novo

implant installation and crown restoration.

The different treatment options were explained to the

patient. Option 3 was selected.

Treatment

Initial therapy

The patient was instructed in proper plaque control

procedures. After flap elevation, the implant in site 21

was removed with the use of a calibrated trephine. The

flap was repositioned coronally and closed with inter-

rupted sutures.

Implant placement and bone regeneration

After 2 months of healing following implant removal,

buccal and lingual full thickness flaps were elevated.

The flaps extended from tooth 11 to tooth 22 (Figs. 39-

9, 39-10) and were released with vertical incisions

Fig.

39-8.

The artificial crown was removed. It was pos

sible to recognize the "overcontoured" surfaces on both

the buccal and the palatal aspect of the crown.

Fig.

39-9. After implant removal and 2 months of heal

ing, the site demonstrated the presence of a deep defect

in the bone. Also the soft tissue was compromised.

Fig.

39-10.

A full thickness flap was reflected both buc

cally and palatally, extending from tooth 11 to tooth

22.

placed at the distal line angle of teeth 11 and 22. The

bone surface was carefully curetted and all residual

soft tissue was removed from the defect.

An implant (13 mm long) was placed in a proper

position with the implant shoulder 3 mm apical of the

free gingival margin of the adjacent teeth. This re-

sulted in an implant exposure outside the buccal bone

housing of about 8 mm (Fig. 39-11).

A reinforced e-PTFE membrane was adapted and

fixed palatally with the use of titanium pins. A par-

ticulated bone graft was collected from the retromolar

902 • CHAPTER 39

Fig. 39-11. An implant was placed with the shoulder lo-

cated 3 mm apical of the free gingival margin of the ad-

jacent teeth. This resulted in an implant exposure out-

side the buccal bone of about 8 mm.

Fig. 39-12. A particulated bone graft was collected from

the retromolar area in the mandible and was packed

into the bone defect.

Fig. 39-13. A titanium reinforced e-PTFE membrane

was placed and stabilized buccally and palatally with

titanium pins.

Fig. 39-14. The periosteum of the buccal flap was in-

cised and released in order to augment the flap mov-

ability before wound closure.

Fig. 39-15. The wound closure was performed with

horizontal mattress and interrupted suture.

Fig. 39-16. After 6 months of uneventful healing, the e

PTFE membrane was removed.

area in the mandible and was packed into the bone

defect (Fig. 39-12). The membrane was then anchored

to the buccal bone wall with two titanium pins (Fig.

39-

13).

The periosteum of the buccal flap was released in

order to augment the movability of the flap before the

wound was closed with horizontal mattress and inter-

rupted sutures (Figs. 39-14, 39-15).

Membrane removal and abutment connection

After 6 months of healing, the e-PTFE membrane was

removed and a connective tissue graft was placed on

top

of the regenerated bone to increase the thickness

of the

mucosa (Figs. 39-16, 39-17, 39-18). After another

months, the cover screw was exposed and connected to

a regular abutment (Fig. 39-19).

Restorative therapy

A provisional acrylic crown was prepared and in

serted

after one additional month of healing. The

emergence

profile of the crown was modified repeat

edly during the

next 6 months to condition the soft

PROCEDURES USED TO AUGMENT THE DEFICIENT ALVEOLAR RIDGE • 903

Fig. 39-17. A thin layer of connective tissue could be

seen on the surface of the regenerated bone.

Fig. 39-18. A connective tissue graft was placed on top

of the regenerated bone to increase the thickness of the

mucosa.

Fig. 39-19. After 2 months the cover screw was exposed

and connected with a regular abutment.

Fig. 39-20. A Procera® made full porcelain crown was

inserted.

tissue, and finally a "Procera® crown" (Nobel Biocare,

Gothenburg, Sweden) was fabricated and inserted

(Fig.

39-20).

Concluding remarks

This case showed that GBR techniques can also be

effectively used for the treatment of peri-implant bone

defects in the anterior region of the maxilla. The treat-

ment included a series of surgical and prosthetic steps

but resulted in proper function and an optimal esthetic

outcome.

Patient 2 - Alveolar ridge augmentation for

implant restoration in the anterior maxilla

A 22-year-old man had been involved in a motorcycle

accident in which the two upper central incisors, to-

gether with the associated buccal bone plate had been

lost. The patient was otherwise in good general health

and was a non-smoker.

Initial examination

The patient presented with his natural dentition in

good condition. There were no clinical signs of perio-

dontitis and dental caries. The clinical findings were

confirmed in the radiographic examination. The oral

hygiene examination revealed the presence of modest

amounts of soft and hard supragingival deposits.

The upper central incisors were missing and the

edentulous ridge in this region was insufficient, both in

width and height, for implant installation. The

upper

lateral incisors were vital, exhibiting minute

crown

fractures that had been restored with compos

ite.

Treatment planning

The patient was informed about the lack of sufficient

bone tissue in the upper front tooth region. The differ-

ent treatment modalities that were available were de-

scribed. These included bone augmentation, implant

installation and crown restoration. Further, the antici-

pated long-term result and alternative treatment op-

tions were discussed.

After having evaluated the options, it was decided

that a ridge augmentation procedure including GBR

should be performed with subsequent implant place-

ment and prosthetic reconstruction.

Treatment

Initial therapy

This treatment included patient information, oral hy-

giene instruction and professional tooth debridement

904 • CHAPTER 39

Fig. 39-21. A 22-year-old man had a motorcycle acci-

dent and the two upper central incisors and the buccal

bone plate were lost. A full thickness flap was elevated

both buccally and palatally from tooth 12 to tooth 22.

Fig. 39-22. (a) Three mini-screws were applied to the buccal defect and on top of the bone crest in order to support

membrane and to avoid its collapse into the defect. (b) A titanium reinforced e-PTFE membrane was adapted and

fixed to the palatal aspect of the edentulous bone crest with titanium pins. A particulate autogenous bone graft was

packed into the defect. (c) The membrane was anchored buccally with two titanium pins. (d) A connective tissue

graft

was harvested from the palate and positioned on top of the crest to augment the thickness of the mucosa. (e)

The

flaps were closed with horizontal mattress and interrupted sutures.

PROCEDURES USED TO AUGMENT THE DEFICIENT ALVEOLAR RIDGE • 905

Fig. 39-23. (a) After 6 months of uneventful healing, a full thickness flap was elevated and the membrane exposed.

(

b) The membrane was removed. The mini-screws appear embedded in the regenerated bone.

A Maryland bridge was fabricated and inserted as a

provisional restoration in the upper incisor region.

Ridge augmentation

A full thickness flap was elevated both buccally and

palatally and extended from tooth 12 to tooth 22 (Fig.

39-21). A titanium reinforced e-PTFE membrane was

adapted and fixed to the palatal aspect of the edentu-

lous bone crest with titanium pins. Three mini-screws

were applied to the buccal defect and on top of the

bone crest in order to support the membrane and to

avoid its collapse into the defect (Fig. 39-22a). A par-

ticulated bone graft was collected from the mandibu-

lar symphysis region and placed in the ridge defect

(

Fig. 39-22b). The membrane was then fixed buccally

with two titanium pins (Fig. 39-22c). A connective

tissue graft was harvested from the palate and posi-

tioned on top of the crest to augment the thickness of

the soft tissue (Fig. 39-22d). Releasing incisions were

placed in the periosteum and the flaps were closed

with horizontal mattress and interrupted sutures (Fig.

39-22e). The sutures were removed after 2 weeks.

Membrane removal and implant placement

After 6 months of uneventful healing, a full thickness

flap was elevated and the membrane, pins and screws

were removed (Fig. 39-23a,b). Two 13 mm long im-

plants were placed in region 11 and 21 (Fig. 39-24).

After 6 months, abutment connection was per-

formed (Fig. 39-25a,b). In addition, the fornix was

Fig. 39-24. Two 13 mm long implants were placed in re

gion 11 and 21.

Fig. 39-25. (a)After 6 months of healing, the abutment connection was performed. (b) Two healing abutments were

placed.

906 • CHAPTER 39

Fig.

39-26.

The fornix was deepened with a partial

thickness flap. After one month the mucosa had healed.

Fig.

39-27.

(a) Periapical radiograph demonstrating the amount of new bone formation as well as the provisional

restoration. (b) Two acrylic crowns were inserted.

Fig.

39.28.

The final prosthetic restoration including

two independent (porcelain fused to metal) crowns,

was placed after 4 months of soft tissue

conditioning.

deepened using a partial thickness flap procedure

(Fig.

39-26).

Restorative therapy

The peri-implant tissues were left to heal and mature

for 1 month before two provisional crowns were fab-

ricated and inserted (Fig. 39-27a,b). The final pros-

thetic restorations, including two single crowns (por-

celain fused to metal), were placed after 4 months of

soft tissue maturation (Fig. 39-28).

The patient was incorporated in a supportive care

program that included recall appointments every 6

months.

Concluding remarks

This case describes the different phases included in the

surgical and prosthetic reconstruction of a site which

included two adjacent missing teeth in the upper jaw.

In this particular case the esthetic outcome was of

great importance. Therefore, a number of different

procedures were required to reconstruct both the hard

and the soft tissues.