Prevalence of infection with the use of β-tricalcium phosphate as a bone graft substitute during Le Fort I osteotomy

Abstract

While grafting with bone substitutes has been shown to provide greater stability in maxillary advancements, infection remains a concern with any material that is placed in close proximity to the maxillary sinus. The purpose of this study was to evaluate the prevalence of infection in maxillary advancements in which a bone graft substitute (β-tricalcium phosphate; β-TCP) was placed at the time of surgery. This was a retrospective study of all maxillary osteotomies. Patients were divided into two groups: group 1 included maxillary osteotomies in which β-TCP was not used; group 2 included any maxillary osteotomy where β-TCP was used. The prevalence of infection, slow healing, and need for second surgery due to infection or non union was noted. Fisher’s exact test was used to compare differences between the groups. Records were adequate for 438 patients: group 1 included 297 patients, while group 2 included 141. No infections were noted in either group. In group 2, there was one patient who had delayed union/non-union requiring a second procedure. Statically, there was no significant difference between the two groups ( P = 0.3219). Based on the data obtained in this study, the use of β-TCP does not increase the incidence of infection or complications when used in Le Fort I maxillary osteotomy.

Introduction

Interpositional bone grafts have been used with maxillary osteotomies for many years. Bone grafts and/or their substitutes can act as mechanical stops reducing relapse, provide a scaffold for bone to grow over, and prevent soft tissue herniation or growth into osteotomy sites. Several authors consider that maxillary advancement of more than 4 mm is problematic in terms of relapse. Waite et al. compared the stability of large advancements with and without genial bone grafts. They noted that the patients who received grafts showed greater stability than those who were not grafted.

While autologous bone grafting still plays a significant role in clinical practice, many substitutes have been developed to decrease the morbidity associated with donor sites. Allografts are a biological alternative to autologous grafts, but they carry a small and real risk of transmission of disease. In contrast, β-tricalcium phosphate (β-TCP), a synthetic calcium phosphate ceramic, also allows bony regeneration and substitution of bone, but without the risk of disease transmission. It is a biocompatible and absorbable material. The mechanism of bone formation following it use is osteoconduction. The use of β-TCP as an alternative to traditional bone grafting avoids donor site morbidity and saves time in the operating room.

While β-TCP has been shown to be safe, infection remains a concern with any alloplastic material that is placed in close proximity to the maxillary sinus. Cottrell and Wolford assessed 245 consecutive patients who had coralline hydroxyapatite placed during orthognathic surgery. Of 207 implants that were placed along the lateral sinus wall, 198 remained long term. For the last 6 years, β-TCP (ChronOS; Depuy Synthes, West Chester, PA, USA) has been used routinely to graft maxillary osteotomy sites at the present authors’ institution. In contrast to coralline hydroxyapatite, it is easier to contour and is resorbed in 6–18 months. The purpose of this retrospective study was to determine the prevalence of infection or delayed healing following the use of β-TCP in maxillary osteotomies.

Materials and methods

All maxillary orthognathic surgeries done in the department of oral and maxillofacial surgery of the study institution between January 2009 and June 2015 were reviewed. The records were inspected for infection, slow healing, and the need for a second operation. Two groups of patients were selected: group 1 comprised patients for whom β-TCP was not used during the osteotomy (control group), and group 2 included patients in whom β-TCP was used during the osteotomy. Group 2 included maxillary advancements of ≥4 mm in which β-TCP was wedged between the advanced maxilla and the residual skeletal base, as well as segmented maxillary osteotomies in which β-TCP was wedged between the segments. In both cases, the β-TCP was in close proximity to the maxillary sinus.

The patients in group 2 were sub-divided into two groups: one-piece and multiple-piece maxillary osteotomies. The one-piece maxillary osteotomies were further divided into three subgroups according to the degree of advancement: minor advancement (<5 mm), medium (5–8 mm), and major advancement (>8 mm). The segmental osteotomies consisted of two- and three-piece maxillary osteotomies in which β-TCP was used to fill the interdental gaps ( Table 1 ) .

Table 1
Distribution of patients in group 2 (β-TCP used following osteotomy).
Number of cases Percentage
One-piece maxillary osteotomy *
Minor (<5 mm) 0 0%
Medium (5–8 mm) 28 19.9%
Major (>8 mm) 43 30.5%
Multiple-piece maxillary osteotomy 70 49.6%
β-TCP, β-tricalcium phosphate.

* Patients in the one-piece maxillary osteotomy group were further divided into three subgroups according to the degree of advancement.

For group 1, the inclusion criteria were Le Fort I osteotomy in one or more pieces where β-TCP was not used; complete records; follow-up of ≥6 months. Exclusion criteria were incomplete follow-up data; use of any grafting material; syndromic patients; patients with cleft lip and palate; previous surgery; a history of trauma.

For group 2, the inclusion criteria were one-piece Le Fort I osteotomy with ≥4 mm advancement, or segmental Le Fort I osteotomy; use of β-TCP in the osteotomy gap; follow-up of ≥6 months. Exclusion criteria were incomplete follow-up data; use of other grafting materials; syndromic patients; patients with cleft lip and palate; previous surgery; a history of trauma.

Fisher’s exact test was used to compare differences between the groups, with significance set at a P ≤ 0.05.

β-Tricalcium phosphate bone graft substitute

ChronOS bone graft substitute (Depuy Synthes) is a synthetic β-TCP bone void filler; it is radiopaque, resorbable, and osteoconductive. The material contains calcium and phosphorus and it is resorbed and replaced by bone in 6–18 months. It has a similar radiopacity to bone; thus β-TCP is frequently difficult to identify in two-dimensional images. Fig. 1 shows a cone beam computed tomography (CBCT) scan obtained immediately postoperative for a Le Fort I advancement case in which β-TCP was used. Fig. 2 shows a CBCT scan obtained at 6 months after surgery; the β-TCP has been resorbed and replaced by bone.

Fig. 1
CBCT obtained immediately postoperative showing the interpositional β-TCP on the lateral and anterior walls of the maxillary osteotomy.

Fig. 2
CBCT obtained at 6 months postoperative for a patient who underwent Le Fort I advancement with the use of β-TCP as a bone substitute in the osteotomy. The β-TCP has been completely resorbed and complete bone healing has occurred.

Technique

All Le Fort I osteotomies were performed in a similar fashion. In the control group, the maxilla was moved in a variety of directions, but β-TCP was not used as an adjunctive material. In group 2, after the maxilla had been advanced to the desired position, bone plates were used to fix the segments. β-TCP was contoured with a number 15 Bard Parker blade ( Fig. 3 ) and wedged into any gaps ≥4 mm in size, ensuring contact with the bony segments ( Fig. 4 ). The material is brittle, but it can easily be carved with a number 15 scalpel blade. In segmental Le Fort I osteotomies, the material was wedged into the interdental gaps after the fabricated splint was ligated to the segments prior to the maxilla being fixed. The segments were gently pried apart with a periosteal elevator to allow the material to be held firmly once the periosteal elevator was removed.

Fig. 3
β-TCP wedges can easily be carved to fit the osteotomy gaps using a No. 15 Bard Parker blade.

Fig. 4
β-TCP placed in the osteotomy gap near the piriform aperture of a large maxillary advancement.

This study was approved by the necessary institutional review board.

Materials and methods

All maxillary orthognathic surgeries done in the department of oral and maxillofacial surgery of the study institution between January 2009 and June 2015 were reviewed. The records were inspected for infection, slow healing, and the need for a second operation. Two groups of patients were selected: group 1 comprised patients for whom β-TCP was not used during the osteotomy (control group), and group 2 included patients in whom β-TCP was used during the osteotomy. Group 2 included maxillary advancements of ≥4 mm in which β-TCP was wedged between the advanced maxilla and the residual skeletal base, as well as segmented maxillary osteotomies in which β-TCP was wedged between the segments. In both cases, the β-TCP was in close proximity to the maxillary sinus.

The patients in group 2 were sub-divided into two groups: one-piece and multiple-piece maxillary osteotomies. The one-piece maxillary osteotomies were further divided into three subgroups according to the degree of advancement: minor advancement (<5 mm), medium (5–8 mm), and major advancement (>8 mm). The segmental osteotomies consisted of two- and three-piece maxillary osteotomies in which β-TCP was used to fill the interdental gaps ( Table 1 ) .

Dec 14, 2017 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Prevalence of infection with the use of β-tricalcium phosphate as a bone graft substitute during Le Fort I osteotomy
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