Alveolar Bone Grafting



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Alveolar Bone Grafting and Orthodontics in Cleft Palate Surgery

Alveolar Bone Grafting



Principles:

  1. Stabilisation of expanded dentoalveolar segments

    • Prevents collapse of the lesser segment behind the greater segment and the greater segements behind the premaxilla in bilateral clefts

    • Improves occlusal interdigitation and transverse collapse of the expanded maxilla

  2. Allows growing tooth buds to move into cleft (Odontogenic bony support)

    • Provides osseous tissue to support tooth eruption

    • Adequate alveolar bony height prevents periodontal pockets and ensures long term stability and retention of the tooth

  3. elimination of oronasal fistula

  4. Nasal bony support

  5. Enhances facial aesthetics.

  • Aim of alveolar cleft treatment is to restore arch congruity without the need for dentures.

  • The ultimate goal is complete obliteration of the cleft without disturbing facial bone growth.

  • Optimal timing is controversial but most advocate secondary bone grafting.


History:

Drachter (1914) – First used tibial bone as donor for palatoplasty. (German paper)

Veau (1931) – Also reported use of tibia for palatal bone grafts. (French Paper)

Mowlem (1941) – Demonstrated that cancellous bone chips were vascularised rapidly due to honeycomb

structure whilst cortical bone “take” was relatively slow and relied on process of

“Creeping Substitution”.

Axhausen(1952) – First reported use of onlay bone chips from tibia to unite free-floating pre-maxilla with

lateral segments. (German paper)

Various authors reported use of tibia and rib for early bone grafting of clefts (1950-1960)

Scoog (1962) –Technique for primary bone grafting of alveolar defects in patients with bilateral clefts.

Johanson (1966) – First demonstrated that cancellous bone transformed into alveolar bone into which canines

could erupt.

Boyne and Sands (1972) – Pointed out that grafted bone responds physiologically to the orthodontic

movement and migration of teeth. They favoured the use of Ileac bone graft.



Wolfe and Berkowitz (1983) – Reported “Good ossification of bone grafts” using cranial bone as a donor.
Surgical options and timing

  1. No alveolar bone grafting

  • Primary periosteoplasty; Skoog (1965), Massei et al (1979), Millard(1980)

  • wide flap of periosteum from the anterior maxillary wall based medially along the lateral edge of the piriform aperture

  • shows no distinct advantage of long-term stability, and may interfere with growth as much as primary bone grafting.

  • Fairly good ossification expected if performed before age 5.

  • Secondary periosteoplasty – surgicel placed in periosteal pocket to act as matrix for ossification. Usefulness questioned in subsequent studies.

  • Growth studies confirmed no increase in anterior crossbite or maxillary arch length. Higher incidence of buccal crossbite in group with wide clefts.


2. Primary alveolar bone grafting

  • Before two years of age.

  • Advantages

  1. Decreases the time of orthodontic treatments

  2. May reduce the need for orthognathic surgery

  3. Eliminates nasal liqud escape and improves oral hygiene in the preschool and early school periods

  • Preparation

  • Within 1st month of life obturator for complete clefts

  • Passively through the splint and actively from the external closure of the lip corrects the alignment of the maxillary segements

  • Process can be enhanced by an active obturator with an expansion screw

  • Important to optimize alignment to reduce the gap required to bone graft

  • Method

  • GA, mucosal infiltration with vasoconstrictor

  • Trapezoidal mucosal flap is raised into the vestibule of the mouth

  • Exposes the posterior surface of orbicularis

  • Leaflets of mucosa along the cleft margins are raised, turned back, and sutured to create a palatal lining

  • Anterior subperiosteal elevation is limited to the labial surfaces of the alveolus

  • Small rib graft

  • Intact outer cortical segment onlayed on to the labial surface and the inner half morselised and packed into the underlying space

  • Trapezoidal flap is then advanced over the graft (V to Y)



  • Previously widely practiced, largely abandoned due to adverse effects on facial growth and arch form.

  • Primary bone grafting as long as it is accompanied by appropriate maxillofacial orthopedics may have a place - function of this graft is to maintain arch form and not to attempt to close the entire bony cleft, nor to add bone mass for tooth migration.



3. Early secondary bone grafting (Age 2-6 before eruption of lateral incisor)

  • Performed to provide alveolar support for eruption of lateral incisor.

  • CLP patients frequently have congenitally absent, malformed or ectopically erupting lateral incisors.

  • Requires judgement based on radiographic evidence that incisor is present and anatomically normal.

  • If present, eruption of the lateral incisor is thought to favourably influence eruption of canine and obviate the need for a fixed bridge or orthodontic repositioning of the canine into the lateral incisor position.

  • May influence transverse and AP growth of maxilla.


4. Secondary bone grafting (Before eruption of permanent canine teeth – age 7-11)

  1. No need for permanent bridgework if erupting teeth can be brought into the new bone grafted cleft.

  2. Better support for those teeth adjacent to the cleft that were poorly encased in deficient alveolar bone.

  3. Better support for the alar base and nasal platform

  4. Simultaneous closure of oronasal fistulae

  5. Gaps in the dental arch can often be bridged orthodontically without the need for a prosthesis.

  • Other benefits

  • Stabilisation of dento-osteal segments – Greater alveolar segment has tendency to collapse. (2o to lack of alveolar continuity and scarring from palate repair)

  • No adverse effect on maxillary growth (95% of AP and transverse growth of maxilla occurs by age 8)

  • Ideally performed when ¼ to ½ of canine root formed (age 9-12)

  • Berglund et al (1986) – Review of 340 patients bone grafted before canine eruption showed satisfactory bone formation in 98% of grafted sites. Normal eruption/migration of canines through graft in majority.


Keys to success

  1. adherence to meticulous surgical technique;

  2. simultaneous closure of coexisting oronasal or palatal fistula

  3. use of cancellous bone particles only

  4. coverage of the grafts with well vascularized flaps.

Outcome

  • Failures are uncommon <5% - poor tissue quality is responsible

  • Improved oral hygiene reduces soft tissue problems

  • Ilium as the donor produces the best results, particulate bone graft are superior to cortex

  • Reduced incidence periodontal defects and fistulas

  • Note the amount of retained alveolar height is related to whether a tooth has erupted through the graft




  1. Late secondary grafting (after eruption of canines)

  • Patients who have failed or missed treatment with partial eruption of canines prior to orthodontic manipulation or orthognathic surgery.

  • Enables proper positioning and bony support for canine

  • When orthognathic surgery is performed allows manipulation of one-piece maxilla.



Unilateral Clefts

  • Lateral maxillary dentoalveolar collapse is corrected orthodontically prior to bone grafting.

Bilateral Clefts

  • Orthodontic therapy required to expand entire maxillary arch. Orthodontic appliance kept in place at the time of surgery.

  • Bone grafting requires careful attention to maintenance of blood supply to premaxilla

  • Two stage procedure or maintain continuity of labial mucosa in region of premaxilla.

Imperative that at the time of surgery, bone grafts are covered by adequate vascularised soft tissue flaps on the nasal and oral sides.

Good nasal side closure, use of adequate amounts of cancellous bone and a watertight oral side closure are paramount.

Graft Materials


Rib - primary bone grafting

Iliac crest - Particulate marrow and cancellous ileac crest bone grafts (PMCB)

- Anterior or posterior ileac crests. Posterior better for large quantity



Cranial bone - Preferred by some as intramembranous rather than enchondral

Block grafts from mandibular symphysis – Results comparable to iliac crest.

Allogenic bone graft –Predicability of success and potential for normal canine eruption not yet established.

Alloplastic (Hydroxyapetite) – Unsuitable if lateral incisor/canine not erupted or when periodontal bone

support is required

Various authors reported successful use of Iliac crest cancellous bone grafts for alveolar clefts with spontaneous eruption of teeth into the grafted site in the majority of patients making it the “Gold Standard” for alveolar cleft grafting by the late 1980’s.



Treatment Sequence

Orthodontics

Ages 5-6: Interceptive orthodontics is begun and erupted supernumerary teeth in the region of the cleft are removed

Ages 7-8: Maxillary arch expansion

Ages 9-11: Alveolar bone graft

Ages 12-13: Comprehensive orthodontics

Ages 14-16: Orthognathic surgery if necessary

Ages 16-21: Dental reconstruction and rhinoplasty

Patient preparation


Orthodontic management in mixed dentition stage: Alignment of anterior teeth – usually rotated.

Expansion of posterior segments and correction of

anterior crossbites

Expansion appliances left in-situ for 3 months post graft

to prevent relapse

Stabilisation of premaxilla segment in bilateral clefts with arch wire or palatal appliance



Removal of supernumerary or deciduous teeth 6 to 8 weeks prior to grafting. (Improves soft tissue flaps)

Surgical technique:-


  • emphasis on watertight closure and vascularity

  • GA mucosal infiltration

  • Flaps raised on the labial surface of the maxilla from the gingival sulcus of the teeth both anteriorly and posteriorly from the cleft

  • Need to extend to the 1st or 2nd molar and back cut into the sulcus

  • Raised up to and around the piriform aperture and separated from the nasal mucosa

  • Nasal mucosa is repaired directly

  • Palatal mucoperiosteal flaps used to separate the oral cavity from the cleft site




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