Implant Placement & Bone Block Reconstruction

Implant Placement in Esthetic Zone After Bone Block Reconstruction: A Case Report

Abstract

Missing teeth in the esthetic zone compromise functional, esthetical and phonetic status of the patients. Also advancement in dental implant treatment leads to predictable survival rates. Meticulous evaluation of both bone quality and quantity is a major requirement for a successful osseointegrated dental implant treatment. Bone defect associated with extraction sites in anterior maxilla affect both surgical placement of implant and subsequent prosthetic rehabilitation, a correction can be done by using a variety of techniques including barrier membrane with guided bone regeneration, bone block grafts, distraction osteogenesis…
This case report is a step-by-step procedure in which missing tooth 21 is restored with dental implant after autogenous bone block grafting. An immediate provisional restoration was used to create esthetical gingival contour.

Introduction

Restoration of missing anterior maxillary teeth is challenging due to compromised esthetic results associated with missing teeth, in addition to a gradual alveolar bone resorption.¹
The presence of uncompromised bone of adequate volume at the implant site is a major factor in the functional success of the procedure. In addition, by providing predictable support both for the implant itself and for the gingival margin and papillae, it contributes to a pleasing esthetic outcome.^2-3-4
In compromised sites, narrow implants, implants tilted buccally, and implants with oversized clinical crowns could be placed. But this can also lead to unesthetic results and mechanical complications due to improper biomechanics.^5-6
Therefore, bone augmentation surgery is frequently a prerequisite for implant placement.^2-4
A variety of allogenic, alloplastic and xenogenic bonegrafting materials have been suggested in recent years, based on wound-healing mechanisms and bone regeneration principles, such as tissue engineering, and osteoinductive and osteoconductive potential of different biomaterials. ⁷

Autogenous bone harvested from either extraoral or intraoral sites is regarded as the «gold standard» by some, and it remains the material of choice for cortical-cancellous blocks.^8-9

Unlike the sinuses, alveolar ridge does not provide a natural cavity to contain particulated grafting material; therefore graft must display sufficient strength and rigidity to fixate at the recipient site and three-dimensional stability to withstand muscular forces. ^10-11

Case Report

A 21-year-old female patient consulted the Lebanese University Department of Periodontology complaining from absence of maxillary left anterior incisor (21). (Fig.1-2)

Fig 1: Buccal view

Fig 2: Occlusal view

Her medical history revealed no medical contraindication for surgery.

Radiographic evaluation

A peri-apical radiograph displayed an impacted incisor 21 in a horizontal position below the apex of 22. (Fig.3)

Fig 3: Peri-apical radiograph

Treatment modality

The impacted tooth was surgically removed in the department of Oral Surgery at the Lebanese University – School of Dentistry, and 3 months after surgery the clinical exam revealed a good oral hygiene and an acceptable clinical healing
(no marginal gingival inflammation).
No periodontal pockets were detected. No other tooth mobility was found in the vicinity of the surgical wound.

The thickness of the soft tissue of the edentulous ridge was about 2mm measured by a graduated periodontal probe.

There were horizontal bucco-lingual bone defect and labial ridge in form of concavity on clinical occlusal view. (Fig.2)

CBCT evaluation showed an excellent condition of the remaining teeth, and there was adequate bone height of 15 mm. Bucco-lingual bone thickness was 3mm. Bone block was indicated to fill the horizontal defect.

Surgical technique

Surgery was performed under local analgesia (lidocaine + 1/100.000 noradrenaline). A midcrestal incision was made on edentulous site and extended intrasulcularly around the cervical margins of adjacent teeth. Two releasing incisions were made on the distal third of the papilla of the adjacent teeth. Full thickness flap was raised exposing buccal and palatal aspects of alveolar ridge. Periosteal releasing incisions were made with at least 1 cm of overlapping tissue to assure a complete coverage of the graft. A decortication was done with a round bur.

Bone block with suitable measures was harvested from left mandibular ramus under local analgesia, as well.

Fig 4: Flap raising

Fig 5: Donor site

It was seated and fixed with 1.6 mm x 10 mm bone screws. (Fig.6)

Fig 6: Fixation of bone block

A round surgical bur was reapplied to round any sharp cortical edges and shape the block in order to completely conform the defect site. Deficiencies at the edges of the graft were filled with bone substitute (Endobone^®, Biomet 3i, Palm Beach, Garden, Florida, USA). Graft was covered with long term resorbable collagen membrane (Bio-Gide^®, Geistlich biomaterials, Wolhonsen, Switzerland). (Fig.7)

Fig 7: membrane and particule bone graft in place

The midcrestal incision and interdental papillae and vertical incisions were secured with interrupted sutures. (Fig.8)

Oral antibiotics (amoxicillin 500mg, 1 tablet each 6 hours) and analgesics (acetaminophen 500mg, 1 tablet each 4 hours, when needed) were prescribed for 5 days postoperatively and antiseptic solution for 2 weeks. Removable partial denture was modified to prevent pressure the healing tissues and fitted and delivered to the patient immediately after surgery.

Sutures were removed 15 days after surgery and a multiple control visits were scheduled every month to evaluate the progression of the healing.

Fig 8: Suturing the flap

After 6 months, a CBCT was taken before implant placement, there was 8mm bone thickness. (Fig.9)

Fig 9: 6 months post-operatively

For the implant placement surgery, access to augmented ridge was obtained via mid- crestal incision, and intrasulcular incision on the adjacent teeth. Surgical exposure revealed a well integrated block graft into surrounding bone. The fixation screws were removed, and the post-augmentation ridge was measured again to confirm bone gain. A (4.1, 10mm) (Biomet 3i^®, Palm Beach, Garden, Florida, USA) dental implant was then placed in an ideal three-dimensional position.(Fig.10-11)

Fig 10: Implant placement

Fig 11

After surgery, immediate screwed temporisation was performed. Occlusion adjustment was performed in order to keep acrylic tooth out of occlusion.(fig.12)

Fig 12: Temporary crown

Three months later, implants were loaded with final restorations. (Fig.13)

Fig 13: Final crown

Discussion

Esthetic and functional compromises in implant restorations can be prevented by ridge augmentation procedures which results in enhanced emergence profile for an implant supported restoration. A thorough clinical and radiological examination should be done in order to diagnose the exact quantity of bone loss and accordingly plan for various bone augmentation procedures. Autogenous bone grafts are recommended in bone augmentations prior to implant placement because of their osteogenic potential.¹²
Intramembranous autogenous osseous grafts including the mandibular ramus, mandibular symphysis, angle of mandible, maxillary tuberosity and intraoral exostoses, are the “gold standard’’ for improving intraoral osseous volume to facilitate placement of implants.¹³
Alveolar defects can be restored by autologous grafting techniques including corticocancellous blocks, compressed particulate cancellous bone and marrow, and cortical grafts.
Block grafts are associated with minimal resorption and do not usually require the use of an overlying membrane unless the dimensions of the graft are inadequate. Block grafts take longer time to integrate than cancellous bone grafts. When a block graft is used, a staged surgical approach is recommended as opposed to placing the implants in conjunction with the graft.14
The mandibular ramus is a useful, cortical graft that provides primarily dense cortical bone and high concentration of promoter proteins (eg, bone morphogenetic proteins). In addition, the mandibular ramus donor site is associated with fewer postoperative complications, in comparison to the symphysis region.^9-15
Hence they can be successfully used for alveolar ridge augmentation prior to implant placement.

Conclusion

This article addresses a case of alveolar ridge augmentation in a partially edentulous patient prior to implant placement, using autogenous bone grafts harvested from mandibular ramus and secured to the recipient site with osteosynthesis screws. The clinical indication for the case described was the lack of sufficient alveolar bone quantity, a situation that could interfere with esthetics and functional loading of implants. Mandibular ramus block bone grafts provide predictable outcome within a short healing time, exhibit minimum resorption, maintain dense quality of bone (type one or two) and provides ideal sites for endosseous implant placement.

References

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by Dr. Rita Farhat, Dr. Mansour Chantiri, Dr. Cherine Farhat, Dr. Chadi Choueiry, Dr. Badri Meouchy