Maxillary Lateral Ridge Augmentation with Autogenous Mandibular Symphysis graft

Maxillary Lateral Ridge Augmentation with Autogenous Mandibular Symphysis graft Prior to Endosseous Dental Implant Placement: A case report

Keywords

Autogenous bone, ridge deficiency, guided bone regeneration, dental implant, immediate temporization

Abstract

Background

A 33 year old male who have lost his upper anterior incisors due to a car accident several years ago, presented for implant placement. Clinical and radiological examinations revealed an insufficient bucco-lingual width of the edentulous ridge requiring a horizontal bone augmentation prior to implant placement.

Methods

An autogenous bone block graft was harvested from the mandibular symphysis, fixed with titanium miniscrews, covered first with both autogenous and xenograft particles, and second with a resorbable barrier membrane. Six months later, four Astra Tech^® implants were placed in the grafted area demonstrating excellent primary stability allowing for immediate temporization. Three months later the final crowns were placed and periapical radiographs were taken after two years following implant placement.

Discussion

Local grafts from the oral cavity have several advantages on extra-orally harvested grafts as they exhibit little resorption and excellent incorporation at the recipient site. Site development prior to implant placement has become a must in today’s dental practice. Finally implant placement in the anterior maxilla has to meet guidelines proposed in the literature to achieve good esthetics

Conclusion

This case report describes the successful replacement of four missing central incisors following a car accident after a bucco-lingual augmentation of the edentulous ridge.

Introduction

Bone augmentation prior to endosseous dental implant placement in deficient ridges is nowadays a common procedure in dental practice. Because patients’ demands surpassed basic functional needs of having fixed prosthesis alone, an esthetically acceptable prosthesis usually determines the location of endosseous dental implants.

A primary diagnostic consideration for endosseous dental implant placement is the amount of available bone in edentulous area. If, for a certain reason, there is a lack of bone to accomplish a prosthetically driven endosseous dental implant placement, then reconstructive procedures are indicate and required.

Different methods using different materials have been described in the literature for reconstruction of deficient ridges, including autogenous grafts, bone substitutes, and membrane techniques, but autogenous grafts remain the “gold standard” in the repair of alveolar atrophy and bone defects repair.^1,2

Use of autogenous bone grafts was first described by Brånemark and co-workers and is still a well accepted technique for major ridge augmentation procedures.^3,4The iliac crest is often used as donor site although other extra-oral (calvaria)⁵ and intra-oral (mandibular ramus and/or symphysis, maxillary tuberosity…etc) sites have been described.^6,7,8

The morphology of a bony defect is an important consideration in the selection of a method for ridge augmentation. Whenever the size of defect permits to and because of frequent morbidity at extra-oral grafting sites, intra-oral grafting sites are preferred.⁸ Furthermore, there is experimental evidence that intramembranous bone grafts that are placed as block onlay grafts show better volume stability and less postoperative resorption than endochondrial bone obtained from iliac crest.^9,10

The results of mandibular block grafts documented in the literature is favorable and encouraging despite certain limitations and patients’ postoperative temporary neurosensory and functional limited disturbances.¹¹ Block grafts can be harvested from the mandibular symphysis, body and ramus. The different anatomy of these regions results in different graft morphology and volume. So, a proper anatomical and clinical evaluation is needed to decide which site to use to get the best volume and form of bone that corresponds the given defect morphology. ^6,7

Case report

A 33 year old male who lost his maxillary incisors due to a car accident several years ago, wanted to restore his missing teeth with an implant supported fixed prosthesis. Dentascan evaluation (figure. 1) displayed horizontal bony depressions on right and left sides of the midline of the edentulous ridge with enough bone to place fixtures having a diameter of 3.5mm. But, from clinical and prosthetic evaluation, it was obvious that future crowns would have an exaggerated overlap to compensate for normal occlusal relationship, and it would be difficult for the patient to maintain proper oral hygiene in this area consequently. Thickening of these maxillary depressions with an onlay graft was considered before implant placement, to maintain prosthetically accepted crowns with normal occlusal relationship (figures. 2 and 3).

Figure. 1: Preoperative CT scan

Figure. 2: Preoperative maxillary ridge form with obvious horizontal ridge defect

Figure. 3: Preoperative maxillary ridge form with obvious horizontal ridge defect

It was decided to harvest bone blocks from the mandibular symphysis, taking into consideration the size and shape of the defect. Also, morphology of the sympheseal block grafts are more corticocancellous compared to bone blocks from ramus or other intra-oral donor sites. This will insure us earlier revascularization and shorter healing time.¹²

Surgical technique

Patient was prescribed a non steroidal anti-inflammatory NSAID (500 mg mefenamic acid 1 tablet Tid) and antibiotic (500mg amoxicillin with 125mg clavulanic acid 1 tablet Tid) for a period of one week starting the day before the surgery.

Recipient and the donor sites were anesthetized using articaine 2% hydrochloride 72mg containing 1:100 000 epinephrine bitartrate (Septanest, Septodont, France).

At recipient site, a midcrestal incision was performed on the edentulous ridge between the two canines and a full thickness flap was raised to fully expose completely the horizontal ridge defect (figure. 4).

Figure.4 The recipient site after flap raising

Access to symphysis area was obtained by an incision at the mucogingival junction extending from distal side of one canine to the other. A full thickness flap was elevated as well exposing the donor site.

Next, and with sterile paper templates, dimensions of the grafts to be harvested were determined according to the size of defects. Templates were adapted at the chin area with their upper edge being 5mm below the root tips of anterior mandibular teeth as seen on radiographs. Outline of the grafts were marked with a round bur and after removal of templates, osteotomy marks were joined together with a fissure burr using a surgical handpiece with copious chilled saline irrigation. Finally, a flat bone chisel was used to harvest bone blocks (figure. 5).

Figure. 5: Harvested corticocancellous grafts

Before adapting block grafts (figure. 6) to their recipient sites, underlying bone was decorticated and perforated with small round bur to increase revascularization and to improve graft survival.¹² Blocks were secured each with two titanium alloy fixation screws (GBR-System^®, Straumann Dental, Basel, Switzerland) (figure. 7).

Figure. 6: Grafts secured with fixation screws

Figure. 7: Bio-Oss®filling the gaps around onlay grafts

Inorganic bovine bone substitute was used to fill the gaps around the autogenous bone blocks (figure. 8) (Bio-Oss^®, Geistlich Biomaterials, Wolhousen, Switzerland) and the whole grafts were covered with a resorbable collagen membrane (figure. 9) (Bio-Gide®, Geistlich Biomaterials, Wolhousen, Switzerland). Care was taken for the soft tissue flap to cover the grafted edentulous ridge without any tension and sutured with 4/0 resorbable polyglycolic (Safil, Aesculap AG & Co, Tuttlingen, Germany) continuous locking sutures. Donor site was also sutured without having the need to use any hemostatic material. The partial denture that patient had worn was adjusted in a way not to touch the edentulous ridge, and the patient was told not to chew on. Post- operative instructions were given and the patient was seen after one week for check up.

Figure. 8: Grafts covered with Bio-Gide^® membrane

Figure. 9: Postostoperative CT scan, 5 months after surgery

After 6 months another maxillary dentascan showed convex buccal ridge at the recipient site in place of the depressions (figure. 10, 11, 12). Clinically the wax up showed acceptable buccolingual positioning of the restoration. A temporary acrylic bridge was fabricated which was also used as a surgical guide. A second stage surgery was performed to remove the fixation screws and to insert three 3.5mmx15mm endosseous dental implants (Astra Tech, Molndal, Sweden) (figure. 13, 14, 15, 16).

Figure. 10: Postoperative CT scan, 5 months after surgery

Figure. 11: Postoperative CT scan 5 months after surgery

Figure.12: Postoperative ridge form

Figure. 13: The recipient site 6 months after surgery

Figure.14: Implant site prepared

Figure. 15: 3 Astra Tech^® fixtures placed

Figure. 16: Direct abutments in place

Immediately after the placement of three endosseous implants 4mm direct abutments were tightened on fixtures (figure. 17)(Direct Abutment System, Astra Tech^®, Molndal, Sweden). Flap was sutured and immediate temporization was performed (figure. 18). Occlusal adjustments were done in order to keep acrylic bridge out of occlusion. Periapical radiographs were taken immediately after (figure. 19), and the sutures were removed after a week. Three months later, implants were loaded with final restorations and periapical radiographs were taken after 2 years post insertion (figures. 20, 21, 22, 23, 24, 25)

Figure. 17: Temporary bridge in place

Figure. 18: Periapical radiographs 2 months after implant placement

Figures. 19: Final crowns in place 2 years postoperatively

Figure. 20: Final crowns in place 2 years postoperatively

Figure. 21: Final crowns in place 2 years postoperatively

Figure. 22: Final crowns in place 2 years postoperatively

Figure. 23

Figure. 24: Control periapical radiograph 2 years later

Discussion

Local grafts from oral cavity have several advantages, compared to extra-oral grafts. Mandibular grafts are intramembranous in origin which demonstrates accelerated revascularization and healing, compared to endochondral bone grafts. Being cortical bone, they exhibit little resorption and excellent incorporation on the recipient site.¹⁰

Another advantage of intra-oral grafts is that donor and recipient sites are in the same operating field. This provides reduced surgical and analgesia time and offers decreased morbidity from graft harvesting compared to extra-oral donor sites. ⁷

However, there are certain local anatomical limitations in harvesting oral grafts. Size of the sympheseal graft is limited by roots of the mandibular anterior teeth and the pogonion, while the primary limitation of the ramus graft is the inferior alveolar nerve canal.¹³For this reason, intra-oral grafts can be used only for partial (one to four teeth) edentulous span augmentation.¹⁴

Sympheseal graft in particular offers better graft volume and a thicker cancellous component, compared to ramus graft, but is associated with more postoperative complications than ramus graft.⁷

In a study performed by C.M. Misch, incidence of temporary mental nerve paresthesia in symphysis graft patients was found to be 9.6% and 29% of the patients complained of altered sensation of the incisor teeth.⁷

Some authors also described soft tissue dehiscence on donor sites, especially when membranes were used to cover grafts. This is the most detrimental complication associated with onlay grafts and it is due to inadequate flap manipulation and lack of tension free soft tissue closure⁹

Postsurgical complications in our case were only limited to temporary neurosensory disturbance of the chin with loss of sensation of mandibular incisors. These complications were recovered uneventfully 6 months after surgery.

Anorganic bovine bone mineral on the periphery of block grafts appeared well incorporated at the recipient site. Bio-Oss^® particles were firmly attached to the newly formed bone.

The use of Bio-Oss^® is well documented as an inlay bone graft in sinus lift procedures, in extraction sockets, in GTR and in GBR procedures.¹ Histological studies performed by several authors showed up to 37% of intimate contact between Bio-Oss^® particles and woven bone.⁷ Hämmerle and co-workers showed 80% direct bone to Bio-Oss^® contact when covered with e-PTFE membrane and 89% contact without barrier membrane.¹⁶

Zitzman and associates showed in there histological samples obtained from defects filled with Bio-Oss^® particles 6-7 months following grafting, that Bio-Oss® particles occupied 31% of the biopsy area.¹⁷ Berglundh and Lindhe found 17% of the material after 3 months and 11% after 7 months.¹⁸ It is hypothesized that the material participates in the “coupling phenomenon” which is the simultaneous occurrence of bone resorption and bone apposition.¹⁴ This means that this material undergoes remodeling similar to host bone, and it is a biocompatible osteoconductive bone substitute that allows new bone formation. However, little is known about the quality of the regenerated bone in the presence of Bio-Oss^® particles and about the relationship between the newly regenerated bone and implant surface.¹⁷

On the other hand, the quality of the intra-oral block grafts is considered to be type one or two. And the placement of endosseous implants into healed bone graft as a secondary procedure is similar to their use in jaws without bone grafts. ^6,7,10

Placement of endosseous implants simultaneously with bone grafts was followed by complications such as graft detachment, wound dehiscence and higher implant failure rate. Moreover, staged procedure ensures better esthetic results, by optimizing the exact implant positioning.⁹

Conclusion

Intra-oral autogenous block grafts have several advantages over extra-oral grafts:

1) They require shorter healing time compared to extra-oral grafts and bone substitutes.
2) They exhibit minimum resorption.
3) They maintain dense quality of bone (type one or two).
4) Inorganic bovine bone mineral can be used at the periphery and whenever the block size appears inadequate to cover the whole defect. Followed by a barrier membrane to stabilize and protect the particulate graft and to minimize the overall volume loss.
5) However, there are certain limitations concerning size and shape of the graft and some postoperative sensory disturbances for sympheseal graft compared to ramus graft.
6) Symphysis offers thicker graft with more cancellous component than the ramus graft.

References

1. Spin-Neto R, Landazuri Del Barrio RA, Pereira LA, Marcantonio RA, Marcantonio E. and Marcantonio Jr E. Clinical Similarities and Histological Diversity Comparing Fresh Frozen Onlay Bone Blocks Allografts and Autografts in Human Maxillary Reconstruction. Clinical Implant Dentistry and Related Research, 2013;15:490-497.
2. Nissan J, Mardinger O, Calderon S, Romanos G and Chaushu G. Cancellous Bone Block Allografts for the Augmentation of the Anterior Atrophic Maxilla. Clinical Implant Dentistry and Related Research 2011;13:104–111.
3. Chiapasco M, Di Martino G, Anello T, Zaniboni M and Romeo E. Fresh Frozen versus Autogenous Iliac Bone for the Rehabilitation of the Extremely Atrophic Maxilla with Onlay Grafts and Endosseous Implants: Preliminary Results of a Prospective Comparative Study. Clinical Implant Dentistry and Related Research 2013;16:121-128.
4. Brånemark PI, Lindstrom J, Hallen O, et al. Reconstruction of the defective mandible. Scand J Plast Reconstr Surg.1975;9:116-128.
5. Mertens C, Steveling HG, Seeberger R, Hoffmann J and Freier K, Reconstruction of Severely Atrophied Alveolar Ridges with Calvarial Onlay Bone Grafts and Dental Implants. Clinical Implant Dentistry and Related Research, 2013;15:673–683.
6. Donos, N., Kostopoulos, L. and Karring, T. Alveolar ridge augmentation by combining autogenous mandibular bone grafts and non-resorbable membranes. Clinical Oral Implants Research 2002;13:185–191.
7. Misch C.. Comparison of Intraoral Donor Sites for Onlay Grafting Prior to Implant Placement. Int J Oral Maxillofac Implant 1997;12:767—776.
8. Misch C. Use of the Mandibular Ramus as a Donor Site for Onlay Bone Grafting. J Oral Implantol 2000;26: 42-49.
9. Truedsson A, Hjalte K, Sunzel B, Warfvinge G. Maxillary sinus augmentation with iliac autograft – a health- economic analysis. Clin Oral Impl Res 2013;24:1088–1093.
10. Proussaefs P, Lozada J, Kleinman A, Rohrer M. The Use of Ramus Block Grafts for Vertical Alveolar Ridge Augmentation and Implant Placement: A Pilot Study. Int J Oral Maxillofac Implant 2002;17:238-248.
11. Von Arx T, Häfliger J and Chappuis V. Neurosensory disturbances following bone harvesting in the symphysis: a prospective clinical study. Clinical Oral Implants Research 2005;16: 432–439.
12. Verdugo F, D’Addona A and Pontón J. Clinical, Tomographic, and Histological Assessment of Periosteal Guided Bone Regeneration with Cortical Perforations in Advanced Human Critical Size Defects. Clinical Implant Dentistry and Related Research, 2012;14:112–120.
13. Smith B, Rajchel J, Waite D and Read L. Mandibular Anatomy as it relates to Rigid Fixation of the Sagittal Ramus Split Osteotomy. J Oral Maxillofac Surg 1991;49:222-226.
14. Young C, Sandstedt P, Skoglund A. Comparative Study of Anorganic Xenogenic Bone and Autogenous Bone Implants for Bone Regeneration in Rabbits. Int J Oral Maxillofac Implant 1999;14:72-76.
15. Arzi Z, Nemcovsky C, Tal H. Efficacy of Porous Bovine Bone Mineral in Various Types of Osseous Deficiencies: Clinical Observation and Literature review. Int J Periodontics Restorative Dent 2001;21:395-405.
16. Hämmerle CHF, Chiantella GC, Karring T, Lang NP. The Effect of a Deproteinized Bovine Bone Mineral on Bone Regeneration around Titanium Implants. Clin Oral Implants Res 1998;9:151-162.
17. Zitzman N, Schärer P, Marinello C, Schüpbach P, Berglundh T. Alveolar Ridge Augmentation with Bio-Oss: A Histologic Study in Humans. Int J Periodontics Restorative Dent 2001;21:289-295.
18. Berglundh T and Lindhe J. Healing around Implants in Bone Defects Treated with Bio-Oss. Clin Oral Implants Res 1997;8:117-124.

By Dr. Badry Meouchy, Pr. Elie Azar Maalouf, Dr. Sami Mouwakdie, Dr. Cherine Farhat, Dr. Khachig Kourshounian.