Localized bone augmentation and implant site development

LOCALIZED BONE AUGMENTATION AND IMPLANT

SITE DEVELOPMENTChapter 72

Localized bone augmentation and implant site development• Guided bone regeneration• Barrier membranes• Bone graft materials• Autogenous bone

• Localized ridge augmentation• Flap management• Horizontal bone augmentation• Simultaneous implant placement• Complications

Localized bone augmentation and implant site development• Alveolar ridge preservation/management of

extractions• Delayed implant placement• Staged implant placement• Delayed versus staged technique• Immediate implant placement

• Standard implant surgery • Adequate bone volume and quality• Adequate remodeling and maturation of bone

• Surgical bone augmentation• To correct or to prevent alveolar ridge deficiency

Localized bone augmentation and implant site development

• Guided tissue regeneration(GTR) : Specific cells contribute to the formation of specific tissue • Exclusion of the faster-growing epithelium and

CNT from a periodontal wound.• Osteoblasts, cementoblasts and periodontal

ligament cells -> regenerate a new periodontal attachment

Guided tissue regeneration(GTR)

Guided bone regeneration (GBR)• In membrane-protected defects, bone

regeneration was initiated by formation of woven bone along new blood vasculature at the periphery of the defect

• Bone was being isolated from the surrounding soft tissue : GBR

Schenk et al. Int J Oral Maxillofac Implants 1994

Guided bone regeneration (GBR)

• Bone : unique tissue that has capacity to regenerate itself completely

• New bone formation : adequate blood supply

• Biocompatible materials• Protect blood clot• Prevent soft tissue cells from migrating into

bone defect• Resorbable / Nonresorbable materials

GBR: Barrier membranes

• Ideal properties 1. Biocompatibility2. Space maintainance3. Cell occlusiveness4. Good handling properties5. Resorbability or ease of removal(Nonresorbable)


• Nonresorbable barrier membranes• Latex, Teflon (ePTFE, Gore-tex)• Variety of shapes and sizes• Combined with bone graft material for space

maintainer


Case by Prof. Massimo Simion & Dr. Isabella Rocchietta, Italy/UK

• Nonresorbable barrier membranes• Require second surgery to remove (6-12 months)• Stiffer membranes (Titanium-reinforced) :

promote significant amount of new bone


• Nonresorbable barrier membranes• Advantages• Maintain separation of tissue over an extended

time• Disadvantages• If it becomes exposed, it will not heal• Membrane exposure -> infection


• Resorbable barrier membranes• NO second surgery• Polylactide/ polyglycolide(PLA/PGA), Collagen-

based• Support growth of new bone when combine with

bone graft to resist collapse• Reduce bone resorption


• Resorbable barrier membranes• Advantages• No second surgery• Less likely to become expose• Less problematic if they do become exposed

• Disadvantages• May degrade before bone formation complete• The degradation process may produce inflammation• Lack of stiffness -> tenting screws, plates


GBR: Bone graft materials

• To facilitate bone formation within a given space by occupying and allowing subsequent bone growth

• Biologic mechanism • Osteoconduction• Osteoinduction• Osteogenesis

• Osteoconduction• Materials serve as scaffold for bone growth• Osteoblasts from the margins of defect -> bone

formation

Osteoconduction

Osteoinduction

• Osteoinduction• Stimulate osteoprogenitor cells from the defect to

differentiate into osteoblasts -> forming new bone• The induction of bone-forming process by

activating bone-forming cells through mediators• Bone morphogenic proteins (BMP)

Osteogenesis• Osteogenesis• Living osteoblasts : part of the bone graft as in

autogenous bone graft• Osteoblasts form new centers of ossification

within the graft

GBR: Bone graft materials

Autogenous bone• Bone graft materials of choice:

osteoconductive, osteoinductive, osteogenic• No risk of graft rejection• Edentulous space, maxillary tuberosity,

mandibular ramus, mandibular symphysis and healing extraction socket (6-12 weeks)

Autogenous bone

• Disadvantages : increase risk of morbidity• Mandibular symphysis : postoperative bleeding,

bruising, wound dehiscence, damage lower incisors and injury to nerves

• Retrospective analysis of 48 chin graft : 5-mm margin of safety between graft harvest and vital structures

Hunt et al. Int J Periodontics Restorative Dent 1999

• Basic principles to minimize the risk of postoperative morbidity• Radiographic evaluation • Locate mental nerve and foramen• Do not elevate or reflect muscle

attachment beyond the inferior border mandible

• 5 mm safety zone : tooth apices, inferior border of mandible, mental foramen

Autogenous bone

• Basic principles to minimize the risk of postoperative morbidity• Do no harvest deeper than 6mm • Suture the wound in layers• Prevent overheating : 47 °C can cause bone

necrosis -> proper irrigation / Piezoelectric bone surgery

Autogenous bone

Localized bone augmentation and implant site development• Guided bone regeneration• Barrier membranes• Bone graft materials• Autogenous bone

• Localized ridge augmentation• Flap management• Horizontal bone augmentation• Simultaneous implant placement• Complications

Localized ridge augmentation

• Size and morphology of defects : horizontal/ vertical

• Combine with barrier membrane• To achieve good results

• Blood supply• Stable and protect space for bone growth• Tension-free flap wound closure

Flap management

• Incisions, reflection, and manipulation should be designed to• Preserve vascularity of the flap• Minimize tissue injury

• Remote incision : wound opening is positioned away from the graft.

Flap management

• Periosteal releasing incision/ Coronal advancement of the flap + Crestal incision

• To achieve tension-free flap closure

• Suture removal 10-14 days• No prosthesis inserted for 2-3 weeks

• General concepts for flap management• Make incision remote to the placement of barrier

membrane• Elevate full thickness flap 5mm beyond the edge of bone

defect• Vertical releasing should be minimize• Tension-free suture : Periosteal releasing incision

Flap management

• General concepts for flap management• Prosthesis should not be inserted for 2 weeks• Mattress sutures to approximate connective tissue• Interupted sutures to adapt wound closure

Flap management

Horizontal bone augmentation

• Dehiscence / fenestration of implant surface• Maxillary tuberosity graft -> increased ridge

width but 50% resorption

• Block graft from retromolar/ symphysis show no clinical sign of resorption

Ten Bruggenkate et al. Int J Maxillofac Surg 1992

Buser et al. J Oral Maxillofac Surg 1996


• FDBA + Membrane -> increased amount of new bone and no remaining allograft materials in 9 months

• Particulate bone graft• Monobloc bone graft

Doblin et al. Int J Periodontics Restorative Dent 1996Nevin, Mellonig. Int J Periodontics Restorative Dent 1994

• Particulate bone graft• Smaller pieces rapid ingrowth of blood vessels• large osteoconduction surface• more expose osteoinductive growth factors• Lack of rigid• Easily displaced


• Particulate bone graft : indication• Defect with multiple osseous wall that will contain

the graft• Dehiscence or fenestration defect

• Bone graft and barrier membrane combination when bone defect does not containable


Monocortical block graft

• Harvest from the remote site : symphysis, ramus, iliac crest, tibia

• With/without barrier membrane • Screws or plate remove after an adequate of

time (6 months)• Disadvantages: biologic limitation of

revascularizing large block


6 months

Simultaneous implant placement

• In selected case, bone augmentation can be placed simultaneously with implant placement

• good primary stability in native bone


Fenestration defects Dehiscence defects

• Barrier membrane VS periosteal flap coverage of expose implant surface

• Membrane was far superior with regard to bone file

• 66% of treated with membrane resulted in 95-100% elimination of dehiscence


Dahlin et al. Clin Oral Implants Res 1991

Palmer et al. Clin Oral Implants Res 1994

• 55 Branemark implant(machine-surface, external hex) treated by ePTFE membrane alone -> 82% bone fill

-> Cumulative survival rate 84.7%(Max), 95%(Mand)


Dahlin et al. Int J Oral Maxillofac Implants 1995

• The use of graft materials in conjunction with membrane treatment, especially FDBA+GBR

• Success rate of 96.8% (bone fill >90% of dehiscence)


Rominger et al. J Oral Maxillofac Surg 1994

Complications• Bleeding• Postoperative infection• Bone fracture• Nerve dysfunction• Perforation of the

mucosa

• Sinusitis• Pain• Decubital ulcers• Wound dehiscence• Loss of portion of bone

graft

• The amount of new bone formation ->• The length of membrane healing• Size of the defect

• Bone regeneration depend on anatomy of bone defect at the time of implant placement

Complications

Localized bone augmentation and implant site development• Alveolar ridge preservation/management of

extractions• Delayed implant placement• Staged implant placement• Delayed versus staged technique• Immediate implant placement

Alveolar ridge preservation

• Tooth extraction -> alveolar ridge resorption

• Preservation of bone volume -> Goal• First 6- 24 months : most bone loss• Barrier membrane enhance predictability of

bone fill compared with mucoperiosteal flap alone

• Timing of implant placement depend on• Quantity, quality and support of existing bone• Agreement of clinician and patient • Immediate : implant place at the time of extraction • Delayed : implant place approximately 2 months after

extraction • Staged : implant placement allow for substantial bone

healing (4-6 months)


• Tooth extraction : atraumatic surgical technique, avoid bucco-lingual forces

• Remove soft tissue from extraction socket• Evaluate bone level and socket anatomy

• Whether to bone-graft the site, when to place the implant


Delayed implant placement

• Allow time for soft tissue healing to close the wound

• Facilitate more osteogenesis because bone formation is active within the first few months

• Resolution of infection

Staged implant placement

• Allow adequate time for osseous healing : complete hard and soft tissue healing

• Implant place into healed bone sites • Adequate coverage by hard and soft tissues• Disadvantage : require the time for bone

healing

Delayed VS staged technique

• When to place the implant : quantity and location of bone surrounding the tooth

bone sounding

• If little or no bone exists -> require bone augmentation

Immediate implant placementc

• Reduce healing time• Bone-to-implant healing begins immediately

with extraction site healing• Disadvantages : need for subsequent

mucogingival surgery to correct soft tissue

• Implant may be placed in extraction socket along with bone augmentation without flap advancement : One-stage surgery

• One-stage approach with immediate implant placement and provisionalization

Best way to manage hard and soft tissue

Immediate implant placementc

Conclusions

• Localized bone augmentation allow clinicians to reconstruct horizontal alveolar ridge defeciencies

• Implant can be placed simultaneously with the augmentation

• Bone augmentation can be used to preserve alveolar dimension following tooth extraction

Localized bone augmentation and implant site development

Health & Medicine

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