UHM 2011, Vol. 38, No. 2 – HBO2 therapy AND bone stability of dentofacial deformities
The effect of hyperbaric oxygen therapy on improving bony stability in LeFort I maxillary advancement Hany Salah El- Din Eid, BDS, MSD, DDSc1, Waleed El Sayed, BDS, MSD, Ph.D2 1 Faculty 2 Suez
of Dentistry, Misr University for Science and Technology, 6th of October City, Egypt Canal University, Ismailia, Egypt
CORRESPONDING AUTHOR: Dr. Hany Eid –
[email protected]
___________________________________________________________________________________ ABSTRACT Objective: The present study was designed to investigate the effect of hyperbaric oxygen therapy (HBO2T) on improving bony stability in LeFort I maxillofacial surgery.
Methods: Sixteen cases (n=16) with severe skeletal anteroposterior discrepancies and who had ceased growing were used as subjects. The samples were categorized into two groups: Group A comprised onepiece LeFort I procedures with HBO2T administered seven days after surgery (n=8), and Group B comprised the same surgical procedure without HBO2T (n=8). Lateral cephalometric radiographs were taken for each subject to record the occurrence of bony relapse: prior to surgery (T1); seven days after surgery (T2); and a third (T3) taken 12 months after surgery. Each patient underwent preoperative and postoperative full-fixed orthodontic treatment. The first group was administered HBO2T for 60 minutes, at 2.5 ATA (atmospheres absolute) for five consecutive days after the T2 stage, and the second group served as a control, as they had not received HBO2T. For both groups the mean values of T1 stages were calculated and compared to those of T2 and T3 stages in the same group. Results: Comparison between the two groups regarding the percentage of change in measurements at T2 and at T3 showed that there were significant differences between groups in all measurements at T3. In the HBO2T group, there was no statistical significant difference in all parameters between the mean values of T2 and T3, indicating minor or no relapse. Meanwhile in the group without HBO2T, there was a highly significant statistical difference in the mean values between T2 and T3 in all studied parameters, indicating significant relapse. Conclusions: It is suggested that administration of hyperbaric oxygen therapy may aid in the postoperative stability of orthognathic LeFort I surgical corrections of patients with severe dentofacial deformities. ___________________________________________________________________________________ Introduction: For many years, LeFort I surgical procedure has been the routine procedure for correcting severe dentofacial deformity due maxillary deficiency in the anteroposterior plane. Postoperative stability is one of the major objectives in orthognathic surgery. Factors influencing the stability of maxillary advancements have been investigated in many studies; examining single-jaw or bimaxillary procedures, with or without interpositional grafting and with the use of different fixation techniques, primarily wire and miniplate fixation [1-13]. It has been demonstrated that stable results have been reported with the use of rigid fixation without bone grafting or with the use of wire fixation in relatively small advancements of less than 5 mm. In larger advancements and down-graft
procedures, miniplate fixation was found to be more stable than interosseous and suspension wire fixation [9-11, 13-15]. However, inadequate bone recovery would be the expected outcome if the defect between the segments along the line of osteosynthesis is more than 5 mm, as incomplete ossification occurs between the maxillary bone segments at the site of osteosynthesis [17]. This is due to the involvement of fibrotic tissue rather than osseous tissue at the line of osteosynthesis. Therefore, resistance to relapse would be via this fibrotic tissue and the titanium plate and screw commonly used for fixation [16,17]. Hyperbaric oxygen therapy (HBO2T) refers to placing the patient in a chamber to breathe oxygen produced at greater than 1 atmosphere. When oxygen is breathed
Copyright © 2011 Undersea & Hyperbaric Medical Society, Inc.
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UHM 2011, Vol. 38, No. 2 – HBo2 tHerapy aND BoNe staBility of DeNtofacial DeforMities at a pressure of 2 ata (atmospheres absolute), it causes vasoconstriction by decreasing the blood flow rate by up to 20%. the normal tissue partial pressure of oxygen (po2) is 30-40mmHg, but in ischemia caused by infection, trauma or edema, oxygen levels fall much lower [18]. Below 30mmHg, fibroblast and leukocyte functions are severely compromised. Hypoxia (15mmHg) stimulates angiogenesis and capillary budding (if the periphery of the hypoxic area has adequate perfusion/oxygenation). Hyperbaric oxygen (HBo2) increases collagen formation for capillary growth through providing the required matrix to support this process [19]. HBO2 also promotes fibroblast replication, collagen formation and increased bactericidal function of leukocytes to take place while the patient is in the hyperbaric chamber [20]. It has been found that compensation occurs by increasing the tissue oxygen tension (po2), which may reach 250-300mmHg when hyperbaric oxygen is applied [19]. HBo2 is routinely administered at 2 to 3 ata. While the duration of an HBo2 session is typically 90-120 minutes, the duration, frequency and number of sessions have not been standardized [21-23]. Hyperoxygenation, vasoconstriction, bactericidal/bacteriostatic effect, angiogenesis and neovascularization, and direct pressure were found to be the effective mechanisms that enhance the healing of treatment conditions [21,22,24]. oxygen tension has a triggering role in bone remodeling [25]. The increase in oxygen tension causes cellular differentiation to osseous tissue, whereas decreased oxygen tension results in cartilage formation [26]. There is a direct relation between the increase in oxygen tension and increase in osteoblastic and osteoclastic activity [23], where HBO2 treatment was found to cause a significant increase in bone formation in such a manner that lamellar bone develops in the chamber canal [27]. HBo2 treatment was found to be helpful in accelerating the union of autogenous free bone grafts and the tissue incorporation of commercially pure (c.p.) titanium implants in free autogenous bone grafts [28,29]. it was the purpose of this investigation to assess the effect of HBo2 on the stability of the lefort i large maxillary advancements with rigid fixation.
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_____________________________________________ fIGURe 1 _____________________________________________
_____________________________________________ fIGURe 1 – Hyperbaric chamber at the Egyptian Air Force Aero-Medical Institute.
_____________________________________________ MATErIALs And METHods cephalometric data were obtained from a sample of 16 patients (10 male and six female). the mean age was 21.3 years, with a range of 19 to 23 years. The occurrence of the relapses was evaluated by cephalometric analysis performed according to the following: a lateral cephalometric radiograph was taken for each subject prior to surgery (t1); a second was taken seven days after surgery (t2); and a third (t3) was taken 12 months after surgery. the samples were categorized into two groups: Group a comprised one-piece lefort i procedures with HBo2t administered seven days after surgery (n=8), and Group B comprised same surgical procedure without HBo2t (n=8) and served as control. all patients had maxillary hypoplasia in the anteroposterior plane and had ceased growing. the patients were chosen from the cases who were planned to have at least a 5-mm maxillary advancement, which was decided by the cephalometric analyses performed before treatment (mean: 6 mm, and range 5-8 mm ). each patient underwent preoperative and postoperative full-fixed orthodontic treatment. On the seventh day after surgery, the first group was administered HBo2T for 60 minutes at 2.5 ATA for five consecutive days at the egyptian air force aero-Medical institute, cairo, egypt (Figure 1, above). a medical social worker interviewed all candidates who met the criteria of the sample and presented to each individually the possible expected benefits of HBO2t based on a simplified printed literature form prepared for all
UHM 2011, Vol. 38, No. 2 – HBo2 tHerapy aND BoNe staBility of DeNtofacial DeforMities _____________________________________________ fIGURe 2 _____________________________________________
_____________________________________________ fIGURe 3 _____________________________________________
_____________________________________________ fIGURe 2 – Titanium miniplates used to stabilize the repositioned maxilla.
_____________________________________________ patients in different medical fields where HBO2t sessions were recommended for their case by their clinicians. a consent form signed by the patients participating in the study, as well as passing the requirements of an accurate clinical examination performed by a hyperbaric medical doctor (M.D.), were mandatory for all members of the HBo2t group. the HBo2t contraindications served as exclusion criteria. contraindications to hyperbaric oxygen therapy included but were not limited to: patients with untreated pneumothorax, upper respiratory infections, high fevers, emphysema with co2 retention, history of thoracic surgery, malignant disease and middle ear barotraumas. surgical procedure a standard lefort i maxillary down-fracture osteotomy was performed as a single-jaw procedure for all cases; the maxilla was passively repositioned and stabilized with four titanium miniplates (Figures 2 and 3, above). In all cases, no occlusal splints or intermaxillary fixation were used postoperatively. light intermaxillary elastics were inserted at the completion of the procedures and maintained for approximately four weeks. a continuous rectangular orthodontic arch wire (18 x 25) was inserted prior to surgery to provide stability to the fragments.
_____________________________________________ fIGURe 3 – Patient 3: (A, B) preoperative and postoperative photographs. (C, D) preoperative and postoperative cephalometric X-rays.
_____________________________________________ the mean duration of the hospital stay was four days. During the hospital stay, the patients received antibiotics to control any possible postoperative infections. solid diet intake was recommended to take effect in a gradual manner. Mouthwashes four times per day for two weeks were recommended postoperatively to all patients.
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UHM 2011, Vol. 38, No. 2 – HBo2 tHerapy aND BoNe staBility of DeNtofacial DeforMities Measurements the following angular and linear parameters were measured to the nearest degree and millimeter respectively from lateral cephalograms. the radiographs were traced on 0.07-mm acetate paper in a semidark room (Figure 4, right).
_____________________________________________ fIGURe 4 _____________________________________________
Angular measurements 1- angle between sN plane and Na line (sNa); 2- angle between Na and NB lines (aNB); and 3- nasolabial angle (Nla). Linear measurements 1- distance between a perpendicular line dropped from point nasion and point a (N-a); 2- distance between Nperp and anterior nasal spine (N- aNs). cephalometric landmarks • N – nasion: the most anterior point on the frontonasal suture in the midsagittal plane. • S – sella: Geometric center of the pituitary fossa. • ANS – anterior nasal spine: anterior tip of the nasal spine. • Point A: the most posterior midline point in the concavity between aNs and the maxillary alveolar process. • Point B: the most posterior mid line point in the concavity of the mandible between point pogonion (pog) and the mandibular alveolar process. • NLA – nasolabial angle: the angle formed between a line tangent to the base of the nose and a line tangent to the upper lip. • Pog – pogonion: the most anterior point on the bony chin. • Go – gonion: a point on the curvature of the angle of the mandible located by bisecting the angle formed by lines tangent to the posterior ramus and the inferior border of the mandible. • PNS – posterior nasal spine: the posterior spine of the palatine bone constituting the hard palate. statistical methods statistics were done by computer using epi - info. software, version 6.04. a word processing, database and statistics program (WHo, 2001). the tests used were: 1- X mean, sd standard deviation: to measure the central tendency of data and the distribution of data around their mean value.
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_____________________________________________ fIGURe 4 – Cephalometric tracing and landmarks. N– nasion; S–sella; ANS–anterior nasal spine; PNS–posterior nasal spine; A–point A; B–point B; Pog–pogonion; Go–gonion; NlA–nasolabial angle.
_____________________________________________ 2- student’s T-test: for testing statistical significant difference between mean values of two samples. 3- Paired T-test Pt: to test for significant difference between two readings for the same person (before and after intervention or between the two left and right sides). 4- Mann Whitney test: non-parametric test for comparing two groups of data not normally distributed or for small sample size. 5- Percentage of change = 2nd reading – 1st reading / 1st reading x 100 Significant result is considered if p
