CRANIOMAXILLOFACIAL DEFORMITIES/COSMETIC SURGERY
Biodegradable and Titanium Osteosynthesis Provide Similar Stability for Orthognathic Surgery Essam Ahmed Al-Moraissi, BDS, MSc, PhD,* and Edward Ellis III, DDS, MSy Purpose:
The purpose of this study was to test the hypothesis that there is no difference in skeletal stability and material-related complications for titanium or biodegradable fixation when used for various orthognathic surgeries.
Materials and Methods:
A systematic and electronic search of several databases with specific keywords, a reference search, and a manual search through September 2014 was performed. The inclusion criteria were clinical human studies, including randomized controlled trials, controlled clinical trials, and retrospective studies, with the aim of comparing titanium and biodegradable osteosynthesis after various orthognathic surgeries. The outcome variables of horizontal and vertical relapse using cephalometrics and material usability were statistically analyzed.
Results:
The initial PubMed search identified 557 studies, 22 of which met the inclusion criteria (8 randomized controlled trials, 10 controlled clinical trials, and 4 retrospective studies). No statistical difference was found between the 2 groups regarding skeletal stability after various orthognathic surgeries. There was no statistical difference with regard to wound problems, plate and screw removal, and palpability between biodegradable and titanium osteosynthesis, but there was a statistical difference with regard to intraoperative fracture of plates and screws in the biodegradable group.
Conclusion:
The results of this meta-analysis support the hypothesis that biodegradable fixation devices offer similar skeletal stability as titanium fixation for orthognathic surgery. The results of this study also show that titanium fixation produced fewer broken screws during surgery compared with biodegradable screws. Ó 2015 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg -:1-14, 2015
Titanium osteosynthesis is regarded as the gold standard of fixation systems in maxillofacial surgery.1-3 The use of degradable plates and screws remains unpopular for internal fixation among oral and maxillofacial surgeons despite its long history4-6 and well-documented safety. The first reports of their application in orthognathic surgery were published more than 10 years ago7; however, many surgeons hesitate to use degradable systems for orthognathic patients because of their handling properties, longer operation times, cost, and insecurity about their ability to maintain the segments in proper position. Biodegradable fixation devices are made from composites of non-calcined and non-sintered hydroxyapatite
particles, poly-glycolic acid (PGA), or poly-L-lactic acid (PLLA). They are produced by a forging process, which is a unique compression molding and machining treatment. They have a modulus of elasticity close to that of natural cortical bone and can retain high strength during the period required for bone healing. They also can show variable degradation and resorption behavior, osteoconductivity, and bone bonding capability.8 Titanium is sometimes non-electively removed at a second operation after the bone has healed in 5 to 40% of cases.9,10 Biodegradable osteosynthesis has been developed to decrease or even eliminate the need for the removal of titanium plates in those cases
*Assistant Professor, Department of Oral and Maxillofacial
Received December 14 2014
Surgery, Faculty of Dentistry, Thamar University, Thamar, Yemen. yProfessor and Chair, Department of Oral and Maxillofacial
Ó 2015 American Association of Oral and Maxillofacial Surgeons
Surgery, University of Texas Health Science Center, San Antonio, TX.
0278-2391/15/00107-X
Accepted January 26 2015
Address correspondence and reprint requests to Dr Al-Moraissi:
http://dx.doi.org/10.1016/j.joms.2015.01.035
Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Thamar
University,
Thamar,
Redaa
Street,
Yemen;
e-mail:
[email protected]
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2
BIODEGRADABLE VERSUS TITANIUM FIXATION
Table 1. PICOS CRITERIA FOR THE SYSTEMATIC REVIEW
Patients or population (P)
Intervention (I) Comparator or control group (C) Outcomes (O) Study design (S)
Focused question
All patients 15-50 yr old had jaw deformities diagnosed as mandibular prognathism or retrognathism with or without bimaxillary asymmetry and maxillary hypo- or hyperplasia that required orthognathic surgery (BSSO, Le Fort I or both) Biodegradable (bicortical screws) as poly-L-lactic acid Titanium osteosynthesis Postoperative skeletal relapse (linear and angular measurements) and postoperative wound problems and intraoperative plate and screw fractures Clinical human studies, including randomized controlled trials, controlled clinical trials, or retrospective studies, whose aim was comparing skeletal stability and post- and intraoperative complications between bioresorbable and titanium osteosynthesis for various orthognathic surgical procedures Do biodegradable fixation screws have similar skeletal stability for various orthognathic surgical procedures as titanium osteosynthesis?
Abbreviation: BSSO, bilateral sagittal split osteotomy. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
in which removal is necessary. Fewer operations for removal imply less discomfort for patients. It also can benefit society, because fewer removal operations will put less pressure on the capacity of the health care system and preclude patients from missing more work for the removal surgery.11 Additional advantages of biodegradables are their radiolucency and decreased stress shielding because of a progressive decrease in strength and stiffness during degradation, which can stimulate bone healing.12 There is ongoing search for the ideal fixation system.11 Thus, the authors hypothesized that there is no difference in skeletal stability for various orthognathic surgeries (bilateral sagittal split osteotomy [BSSO], Le Fort I osteotomy, or bimaxillary surgery) using titanium or biodegradable fixation. The specific aims were to compare 1) skeletal stability and 2) material-related problems between titanium and biodegradable fixation systems when used to stabilize orthognathic procedures.
Materials and Methods LITERATURE SEARCH STRATEGY
This systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)E 2012 checklist.13 An electronic search of the PubMed, Ovid MEDLINE, and Cochrane CENTRAL online databases was conducted from their respective dates of inception to December 2014. Free text words and Medical Subject Heading terms were used. The headings bioresorbable screws, titanium osteosynthesis, biodegradable osteofixation, poly-L-lactic acid (PLLA), and orthognathic surgery were combined with skeletal stability or relapse. Articles were sought that compared titanium and biodegradable
fixation systems for patients 13 to 50 years old who underwent orthognathic surgery. The low yield led to the use of another search term omitting the reference to bioresorbable OR biodegradable OR poly-L-lactic acid (PLLA) OR PLLA-PGA OR resorbable screws versus titanium OR nonresorbable OR metal for orthognathic surgery (bilateral sagittal split ramus osteotomy) AND (Le Fort I OR bimaxillary surgery OR mandibular OR maxillary setback OR mandibular OR maxillary advancement OR maxillary impaction OR skeletal Class III malocclusion OR Class II) AND (postsurgical movement OR relapse OR skeletal stability OR plate fracture OR postoperative complication OR material-related complication OR B-point OR prognathism OR long face) AND (limit to OR clinical trial OR randomized controlled trial). The abstracts of yielded results were reviewed and the full text was obtained of those with apparent relevance. The references of identified articles were cross-checked for unidentified articles and the individual databases of key subject journals were searched using the same terms listed earlier. These journals were the Journal of Oral and Maxillofacial Surgery, the International Journal of Oral and Maxillofacial Surgery, the Journal of Oral Surgery, and the British Journal of Oral and Maxillofacial Surgery. The searches were limited to articles published in English. An attempt was made to identify unpublished material or to contact authors of published studies for further information. To complete the search, the references of each selected publication on degradable versus titanium osteosynthesis for orthognathic surgery were manually searched. The PICOS criteria for the study are presented in Table 1. The following exclusion criteria were applied: 1) case reports, 2) technical reports, 3) animal or in vitro studies, 4) review papers, 5) uncontrolled
Patients, n Study
Year of Study Publication Design
M/F Ratio
Age (yr), Mean (Range)
Material of Follow-Up Osteo-Fixation Period
Biod
10
10
Class III malocclusion
BSSO
Ti, PLLA
after 1 yr
20
20
Class II skeletal malocclusion dentofacial deformities
BSSO
Ti, PLLA/PGA
6 mo
1997
CCT
NM
Ferretti and Reyneke15 Cheung et al16
2002
CCT
NM
2004
RCT
Biod + Ti, 22.9 (16-37)
30
30
Norholt et al17 Ueki et al18
2004
RCT
total sample, 9/21 NM
NM
29
28
2005
RCT
NM
NM
20
20
Costa et al19
2006
RS
NM
12
10
Landes and Ballon20
2006
CCT
30
30
Turvey et al21
2006
CCT
total sample, 11/24 total sample, 16/18
Biod + Ti, 27.40 (no range given) 25 (16-57), 23/37
35
34
Ueki et al22
2006
CCT
Ti, 26.8 (no range given); Biod, 27.5 (no range given) Biod + Ti, 22.9 (16-34)
26
21
Landes et al23
2007
RS
Biod + Ti, 27 (18-47)
30
15
Oba et al24
2008
CCT
22
23
Dhol et al25
2008
CCT
25
25
maxillary growth disturbance mandibular prognathism Class III malocclusion. 25 patients Angle Class II, 35 Class III dysgnathia isolated mandibular deficiency
Le Fort I, BSSO, self-reinforced genioplasty PLLA
up to 2 yr
Le Fort I, BSSO
after 1 yr
BSSO
Ti, PGA/PLLA copolymer PLLA
Le Fort I, BSSO
Ti, PLLA/PGA
after 1 yr
Le Fort I, BSSO
Ti, PLLA
after 1 yr
BSSO
self-reinforced $1 yr bone screws placed, Ti
mandibular prognathism Le Fort I, with or without BSSO, IVRO bimaxillary asymmetry Le Fort I, BSSO 25 patients Angle Class II, 35 Class III dysgnathia skeletal mandibular BSSO prognathism
vertical maxillary excess, anterior open bite
Le Fort I
Ti, PLLA miniplate
$1 yr
after 1 yr
Ti, PLGA miniplate
PLLA
$1 yr
Ti, PLLA/PGA miniplate
after 1 yr
3
Biod, Ti, 26.4 (no 10/13; range given); Ti, 10/13 Biod, 22.1 (no range given) Biod, Ti, 22.9 (no 8/17; range given); Ti, 5/20 Biod, 23.3 (no range given)
Type of Orthognathic Surgeries
Ti
Harada and Enomoto14
total sample, 8/39 total sample, 22/23
Ti, 22.4 (20-31); Biod, 23 (18-30) NM
Type of Dentofacial Deformity
AL-MORAISSI AND ELLIS
Table 2. CHARACTERISTICS OF INCLUDED STUDIES
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Table 2. Cont’d
Patients, n Study
Year of Study Publication Design
M/F Ratio
2010
RCT
Stockmann et al27
2010
RCT
total sample, 30/72 NM
Paeng et al28
2012
CCT
NM
Ballon et al29
2012
CCT
NM
Buijs et al1
2012
RCT
NM
Ueki et al8
2012
CCT
NM
van Bakelen et al3
2013
RCT
van Bakelen et al11
2014
RCT
Ti, 51/73; Biod, 36/39 NM
Landes et al30
2014
RS
NM
Blakey et al31
2014
RS
Ti, 7/20; Biod, 14/16
Ti
Biod
Type of Dentofacial Deformity
maxillary or 26 BSSO, 11 29 BSSO, mandibular growth 17 Le Fort I, BSSO, 10 disturbances 8 bimaxillary bimaxillary 33 33 23 (80%) mandibular retrognathism, 13 (20%) mandibular prognathism Ti, 25.3 (18-33); 25 25 skeletal Class III Biod, 22.6 malocclusion (18-30) Ti, 25 (16-56); 22 41 Class II and III Biod, 24 malocclusion (16-46) 133 84 dentofacial Biod + Ti, 31 deformities (no range given) Biod + Ti, 23.9 20 20 mandibular (16-48) prognathism with maxillary retrognathism Biod + Ti, 31 134 78 dentofacial (no range deformities given) 22 15 mandibular Ti, 35 (19-59); prognathism Biod, 35 (18-59) 25 25 Class II and III Ti, 24 (15-42); malocclusions Biod, 29 (14-56) Ti, 20.8; Biod, 30 27 NM 19.7 Biod + Ti, 33.5 (no range given) Biod + Ti, 27 (no range given)
Type of Orthognathic Surgeries
Material of Follow-Up Osteo-Fixation Period
Le Fort I, BSSO, PLDLA, Ti BIMX
up to 1 yr
BSSO
8 yr
PLLA
BSSO
resorbable bicortical screws BSSO, Le Fort I, PLLA BIMX
17.8 mo
Le Fort I, BSSO, bioresorbable fractures screws
8 wk
Le Fort I, BSSO
PLLA
$1 yr
Le Fort I, BSSO
Biod
2 yr
BSSO
Biod, Ti
2 yr
Le Fort I, BSSO
F-u-HA/PLLA, Ti
after 1 yr
Le Fort I
poly-lactate PLLDL (70:30), Ti
after 1 yr
$1 yr
Abbreviations: BIMX, bimaxillary surgery; Biod, biodegradable; BSSO, bilateral sagittal split osteotomy; CCT, controlled clinical trial; F, female; F-u-HA/PLLA, forged unsintered hydroxyapatite with poly-L-lactide; IVRO, intraoral vertical ramus osteotmy; M, male; NM, not mentioned; PLDLA, poly-L/DL-lactic acid; PLLA/PGA, poly-L-lactic acid and polyglycolic acid; PLLDL, poly-L/DL-lactic; RCT, randomized controlled trial; RS, retrospective study; Ti, titanium. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
BIODEGRADABLE VERSUS TITANIUM FIXATION
Tuovinen et al26
Age (yr), Mean (Range)
Study
Year of Publication
Type of Surgery
Harada and Enomoto14 Bjuis et al1 Ferretti and Reyneke15 Cheung et al16 Norholt et al17
1997 2012 2002
BSSO
Magnitude of Movement (mm)
Relapse (mm)
Significance
BSSO
— — —
— — 0.83 Biod, 0.25 Ti
no statistical difference no statistical difference no statistical difference
2004 2004
Le Fort I Le Fort I
— 2-3 Biod, 2-3 Ti
comparable function no statistical difference
Ueki et al18 Ueki et al22
2005 2006
6.75 Biod, 6.55 Ti 5.75 Biod, 6.25 Ti
Costa et al19
2006
BSSO BSSO + Le Fort I, IVRO + Le Fort I BIMX
— 0.16 Biod, maxilla; 1.33 Biod, mandible; 0.90 Ti, maxilla; 3.19 Ti, mandible comparable 0.2 Biod, 1.4 Ti
Turvey et al21 Landes and Ballon20
2006 2006
BSSO BIMX
3.54 Biod, maxilla; 4.29 Ti, mandible — 3.5 Biod, 5.4 Ti
0.16 Biod, maxilla; 1.33 Biod, mandible; 0.90 Ti, maxilla; 3.35 Ti, mandible comparable 0.2 Biod, 1.4 Ti
Landes et al23
2007
BIMX
2.5 Biod, maxilla; 5.5 Ti, mandible
Dhol et al25 Oba et al24
2008 2008
Le Fort I BSSO
— 9.1 Biod, 7.0 Ti
1.2 Biod, maxilla; 0.8 Biod, mandible; 1.4 Ti, mandible; 34.2 Ti, mandible 0.2 Biod, 1.4 Ti —
Stockmann et al27 Tuovinen et al26 Paeng et al28 Ballon et al29 Ueki et al8 van Bakelen et al11 Lands et al30
2010
BSSO
—
6% Biod, 6% Ti
no statistical difference horizontal maxillary stability inferior to vertical in Biod group bioresorbable fixation is reliable in segment fixation as Ti no statistical difference bioresorbable fixation might be effective in properly selected cases no statistical difference
2010
BSSO, Le Fort, BIMX
—
—
no statistical difference
2012 2012 2012 2014
BSSO BSSO, Le Fort I Le Fort I BSSO
6.7 Biod, 6.7 Ti 4.9 Biod; 1.3 Ti 6 Biod, 6 (15) —
no statistical difference Biod less stable than Ti no statistical difference no statistical difference
2014
Le Fort I, BSSO
Blakey et al31
2014
Le Fort I
Le Fort, 4, 56 Biod, 6.04 Ti; BSSO, 4.64 Biod, 7.30 Ti 5.6 Biod, maxilla; 7.1 Ti, maxilla
comparable — — vertical, 0.03 Biod, 0.3 Ti; horizontal, 0.1 Biod, 0.3 Ti Le Fort, 3, 82 Biod, 3.25 Ti; BSSO, 2.98 Biod, 8.72 Ti —
AL-MORAISSI AND ELLIS
Table 3. TYPES OF ORTHOGNATHIC SURGERY, MAGNITUDE OF MOVEMENTS, RELAPSE, AND SIGNIFICANCE OF OUTCOMES WITHIN INCLUDED STUDIES
no statistical difference no statistical difference no statistical difference
no statistical difference no statistical difference
Abbreviations: BIMX, bimaxillary surgery; Biod, biodegradable; BSSO, bilateral sagittal split osteotomy; Ti, titanium.
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Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
6 — — — — — — Biod, 1; Ti, 2 — — — — — — — — — — — — — — Biod, 3; Ti, 13 — — — Biod, 59; Ti, 43 Biod, 39; Ti, 44 — — — — — — Biod, 2; Ti, 1 Biod, 1; Ti, 2 Biod, 12; Ti, 16
Ti, 3; Biod, 2 Biod more than Ti Ti, 10; Biod, 11 Ti, 3; Biod, 6
22 articles included in qualitative and quantitative synthesis (metaanalysis)
257 articles screened through titles and abstracts
200 articles excluded due to topic-off
35 of records excluded due to they did not meet inclusion criteria
FIGURE 1. Study screening process.
Abbreviations: Biod, biodegradable; Ti, titanium.
Biod, 0; Ti, 0 Biod, 0; Ti, 0 Biod, 0; Ti, 0 Biod, 1; Ti, 0 — Biod, 1; Ti, 0 — Biod, 5; Ti, 0 Biod, 1; Ti, 1 Biod, 0; Ti, 0 Biod, 0; Ti, 0 Biod, 0; Ti, 0 Biod, 2; Ti, 1 Biod, 1; Ti, 0 Biod, 1; Ti, 1 Biod, 1; Ti, 2 Biod, 11; Ti, 4 Biod, 2; Ti, 3 Dhol et al25 Ferretti and Reyneke15 Harada and Enomoto14 Norholt et al17 Paeng et al28 Stockmann et al27 Tuovinen et al26 Buijs et al1 van Bakelen et al3
Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
Biod,7 plates and 72 screws (75% in Le Fort I); Ti, none — — — — Biod, 4; Ti, 0; (screw head) Biod, 5; Ti, 1; (screw head) — — — Ti, 3; Biod, 2 Biod, 3; Ti, 3 Cheung et al16
Infection
Wound Dehiscence
Intraoperative Plate Fractures
Plate Removal
Plating Timing
300 articles excluded due to duplications
57 articles of full text assessed for eligibility
Study
Table 4. COMPLICATIONS AMONG INCLUDED STUDIES
557 of records identified through electronic database and hand searching
Plate Palpability
Sinus Tract
BIODEGRADABLE VERSUS TITANIUM FIXATION
clinical studies, 6) studies that did not report data (mean and standard deviation) required to perform a meta-analysis, and 7) publications in which the same data were published by the same groups of researchers. The authors carefully assessed the eligibility of all studies retrieved from the databases. From the included studies in the final analysis, the following data were extracted: authors, year of publication, study design, gender (male, female), mean age in years, numbers of patients in groups, type of dentofacial deformities, material used for osteosynthesis, follow-up period, and confounding factors (Table 2).1,3,8,11,14-31 The selected articles were used to compare the primary outcome variables and skeletal stability (using cephalometrics) and material-related problems (predictor variables) for orthognathic surgery. A methodologic quality rating was performed by combining the proposed criteria of the Meta-Analysis of Observational Studies in Epidemiology statement (MOOSE),32 the Strengthening the Reporting of Observational Studies in Epidemiology statement (SROSES),33 and the PRISMA34 to verify the strength of scientific evidence in clinical decision making. The classification of risk for bias potential for each study was based on the following 5 criteria: random selection in the population, definition of inclusion and exclusion criteria, report of losses to follow-up, validated measurements, and statistical analysis. A study that included all these criteria
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AL-MORAISSI AND ELLIS
Table 5. CRITICAL APPRAISAL (QUALITY ASSESSMENT) OF INCLUDED STUDIES
Study Harada and Enomoto14 Ferretti and Reyneke15 Cheung et al16 Norholt et al17 Ueki et al18 Costa et al19 Landes and Ballon20 Turvey et al21 Ueki et al22 Landes et al23 Oba et al24 Dhol et al25 Tuovinen et al26 Stockmann et al27 Paeng et al28 Ballon et al33 Buijs et al1 Ueki et al8 van Bakelen et al3 van Bakelen et al11 Landes et al30 Blakey et al31
Year of Publication
Random Selection in Population
Defined Inclusion and Exclusion Criteria
Loss to Follow-Up
Validated Measurement
Statistical Analysis
Estimated Potential Risk of Bias
1997
no
yes
yes
yes
yes
moderate
2002
no
yes
yes
yes
yes
moderate
2004 2004 2005 2006 2006
yes yes yes yes no
yes yes yes yes yes
yes yes yes yes yes
yes yes yes yes yes
yes yes yes yes yes
low low low low moderate
2006 2006 2007 2008 2008 2010 2010
no no no no no no yes
yes yes yes yes yes yes yes
yes yes yes yes yes yes yes
yes yes yes yes yes yes yes
yes yes yes yes yes yes yes
moderate moderate moderate moderate moderate moderate low
2012 2012 2012 2012 2013
yes no yes no yes
yes yes yes yes yes
yes yes yes yes yes
yes yes yes yes yes
yes yes yes yes yes
low moderate low moderate low
2014
yes
yes
yes
yes
yes
low
2014 2014
no no
yes yes
yes yes
yes yes
yes yes
moderate moderate
Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
was classified as having a low risk of bias, and a study that did not include 1 of these criteria was classified as having a moderate risk of bias. When at least 2 criteria were missing, the study was considered to have a high risk of bias. ANALYSIS OF SELECTED STUDIES
Meta-analyses were conducted only if there were studies of similar comparisons and reporting the
same outcome measurements. For binary outcomes, the authors planned to calculate a standard estimation of risk difference (RR) by the random-effects model if heterogeneity was detected. Otherwise a fixed-effect model with a 95% confidence interval (CI) was performed. Weighted mean difference (WMD) or standard mean difference (SMD; if the studies used different instruments to measure outcomes) was used to construct forest plots of continuous data. In addition, benefit-and-risk analyses were performed in which the
FIGURE 2. Forest plots for the angle formed by the sella, nasion, and B point (degrees; angular measurement; continuous data) after bilateral sagittal split osteotomy using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
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BIODEGRADABLE VERSUS TITANIUM FIXATION
FIGURE 3. Forest plots for horizontal changes (millimeters; linear measurement; continuous data) after bilateral sagittal split osteotomy using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
number needed to treat, with 95% CIs, was calculated for persistent inferior alveolar nerve disturbances. The data were analyzed using the statistical software Review Manager 5.2.6 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark, 2012).26 For those studies that had heterogeneity of their data, no attempt was made to perform a metaanalysis. The means of surgical movements and relapse were calculated by weighted means (Table 3). Postoperative complications, including infection, wound dehiscence, intraoperative plate fractures, plate removal, plate palpability, plating timing, and sinus tract, were recorded and are presented in Table 4. ASSESSMENT OF HETEROGENEITY
The importance of any discrepancies in the estimates of the treatment effects of the different trials was assessed by the Cochran test for heterogeneity and the I2 statistic, which describes the percentage
of total variation across studies that is due to heterogeneity rather than chance. Heterogeneity was considered statistically significant at a P value less than .1. A rough guide to the interpretation of I2 given in the Cochrane handbook35 is as follows: 1) from 0 to 40%, the heterogeneity might not be important; 2) from 30 to 60%, there might be moderate heterogeneity; 3) from 50 to 90%, there might be substantial heterogeneity; and 4) from 75 to 100%, there is considerable heterogeneity. Ideally, all studies should be performed in the same manner with the same experimental protocols. If not, heterogeneity increases. Heterogeneity refers to the variation in study outcomes between studies. When high, different statistics must be applied (random-effects model).
Results The final number of articles selected according to the initial and final selection criteria are presented in
FIGURE 4. Forest plots for vertical changes (millimeters; linear measurement; continuous data) after bilateral sagittal split osteotomy using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
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AL-MORAISSI AND ELLIS
FIGURE 5. Forest plots for the angle formed by the sella, nasion and A point (degrees; angular measurement; continuous data) after bimaxillary surgery using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
Figure 1. The search strategy resulted in 557 articles on biodegradable versus titanium fixation in orthognathic surgical procedures, namely BSSO, Le Fort I, and bimaxillary surgery (advancement or setback surgery or both). After selection according to the inclusion and exclusion criteria, 22 articles1,3,8,11,14-31 qualified for the final review. Eight studies11,14,15,18,21,24,27,28 compared biodegradable and titanium fixation osteosynthesis after BSSO advancement (6 studies) and setback (2 studies). Thirteen studies1,3,8,16,17,19,20,22,23,26,29-31 compared biodegradable and titanium fixation osteosynthesis after bimaxillary surgery in which BSSO and Le Fort I osteotomies was performed for advancement or setback (according to the deformities). Two studies25,31 examined isolated Le Fort I maxillary surgery, 1 examined maxillary impactions,25 and 1 examined maxillary advancement.31 Twenty studies8,11,14-31 assessed the postoperative stability between biodegradable and titanium fixation. Ten studies1,3,14-17,25-28 compared intraoperative and postoperative complications after various orthognathic surgeries when using biodegradable or titanium fixation. Ten studies were controlled clinical trials,14,15,21,22,24,25,28,29 8 were randomized controlled trials,1,3,16-18,25-27 and 4 were retrospective studies.19,23,30,31 Concerning the quality assessment of the included studies, 10 studies1,3,11,16-19,27,28 showed a low risk of bias and 13 studies8,14,15,20-26,29,31 showed a moderate risk of bias. The scores are listed in Table 5.
RESULTS OF INDIVIDUAL VARIABLES
Skeletal Stability BSSO—biodegradable versus titanium osteosynthesis. Angular measurement—sella, nasion, and B point (degrees). Three studies8,18,28 of 130 patients (titanium, n = 65; biodegradable, n = 65) compared changes in the angle formed by the sella, nasion, and B point after BSSO at follow-up periods ranging from 12 to 17.8 months. There was no significant difference between the 2 groups (random: WMD = 0.03 ; 95% CI, 0.38 to 0.44 mm; P = .88). The test of heterogeneity among all studies showed homogeneity (c2 = 1.57; df = 2; P < .46; I2 = 0%; Fig 2). Linear measurements—horizontal changes in millimeters. Eight studies11,14,15,18,21,24,28,30 of 338 patients (biodegradable, n = 171; titanium, n = 167) compared horizontal skeletal changes after BSSO at follow-up periods ranging from 6 months to 1 year. There was no significant difference between the 2 groups, but the result still favored the titanium group (random: SMD = 0.11 mm; 95% CI, 0.52 to 0.30; P = .59). The test of heterogeneity among all studies showed heterogeneity (c2 = 91.56; df = 14; P < .001; I2 = 85%); therefore, a random-effects model was used (Fig 3). Linear measurements—vertical changes in millimeters. Six studies8,11,14,21,24,30 of 225 patients (biodegradable, n = 110; titanium, n = 115) compared vertical skeletal changes after BSSO at follow-up periods to 1 year. There was no significant
FIGURE 6. Forest plot for occlusal cant (millimeters; angular measurement; continuous data) after bimaxillary surgery using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
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BIODEGRADABLE VERSUS TITANIUM FIXATION
FIGURE 7. Forest plot for horizontal changes (millimeters; angular and linear measurements; continuous data) after bimaxillary surgery using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
difference between the 2 groups, but the results still favored the titanium group (random: SMD = 0.06 mm; 95% CI, 0.44 to 0.31; P = .74). The test of heterogeneity among all studies showed heterogeneity (c2 = 48.75; df = 11; P < .001; I2 = 77%); therefore, a random-effects model was used (Fig 4). Bimaxillary surgery—biodegradable versus titanium osteosynthesis. Angular measurement—sella, nasion, and A point (degrees). Three studies8,19,22 of 86 patients (titanium, n = 44; biodegradable, n = 42) compared changes in the angle formed by the sella, nasion, and A point after bimaxillary surgery at follow-up periods of 1 year. There was no significant difference between the 2 groups, but the results favored the titanium group (random: WMD = 0.95 ; 95% CI, 1.98 to 0.08 mm; P = .07). The test of heterogeneity among all studies showed homogeneity (c2 = 0.20; df = 2; P < .91; I2 = 0%; Fig 5). Angular measurement—occlusal cant in millimeters. Three studies8,17,22 of 119 patients (titanium, n = 60; biodegradable, n = 59) compared occlusal canting after bimaxillary surgery at follow-up periods of 1 year. There was no significant difference between the 2 groups (random: WMD = 0.17 ; 95% CI, 1.86 to 1.53 ; P = .84). The test of heterogeneity among all studies showed heterogeneity (c2 = 36.20; df = 2; P
Biodegradable and Titanium Osteosynthesis Provide Similar Stability for Orthognathic Surgery Essam Ahmed Al-Moraissi, BDS, MSc, PhD,* and Edward Ellis III, DDS, MSy Purpose:
The purpose of this study was to test the hypothesis that there is no difference in skeletal stability and material-related complications for titanium or biodegradable fixation when used for various orthognathic surgeries.
Materials and Methods:
A systematic and electronic search of several databases with specific keywords, a reference search, and a manual search through September 2014 was performed. The inclusion criteria were clinical human studies, including randomized controlled trials, controlled clinical trials, and retrospective studies, with the aim of comparing titanium and biodegradable osteosynthesis after various orthognathic surgeries. The outcome variables of horizontal and vertical relapse using cephalometrics and material usability were statistically analyzed.
Results:
The initial PubMed search identified 557 studies, 22 of which met the inclusion criteria (8 randomized controlled trials, 10 controlled clinical trials, and 4 retrospective studies). No statistical difference was found between the 2 groups regarding skeletal stability after various orthognathic surgeries. There was no statistical difference with regard to wound problems, plate and screw removal, and palpability between biodegradable and titanium osteosynthesis, but there was a statistical difference with regard to intraoperative fracture of plates and screws in the biodegradable group.
Conclusion:
The results of this meta-analysis support the hypothesis that biodegradable fixation devices offer similar skeletal stability as titanium fixation for orthognathic surgery. The results of this study also show that titanium fixation produced fewer broken screws during surgery compared with biodegradable screws. Ó 2015 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg -:1-14, 2015
Titanium osteosynthesis is regarded as the gold standard of fixation systems in maxillofacial surgery.1-3 The use of degradable plates and screws remains unpopular for internal fixation among oral and maxillofacial surgeons despite its long history4-6 and well-documented safety. The first reports of their application in orthognathic surgery were published more than 10 years ago7; however, many surgeons hesitate to use degradable systems for orthognathic patients because of their handling properties, longer operation times, cost, and insecurity about their ability to maintain the segments in proper position. Biodegradable fixation devices are made from composites of non-calcined and non-sintered hydroxyapatite
particles, poly-glycolic acid (PGA), or poly-L-lactic acid (PLLA). They are produced by a forging process, which is a unique compression molding and machining treatment. They have a modulus of elasticity close to that of natural cortical bone and can retain high strength during the period required for bone healing. They also can show variable degradation and resorption behavior, osteoconductivity, and bone bonding capability.8 Titanium is sometimes non-electively removed at a second operation after the bone has healed in 5 to 40% of cases.9,10 Biodegradable osteosynthesis has been developed to decrease or even eliminate the need for the removal of titanium plates in those cases
*Assistant Professor, Department of Oral and Maxillofacial
Received December 14 2014
Surgery, Faculty of Dentistry, Thamar University, Thamar, Yemen. yProfessor and Chair, Department of Oral and Maxillofacial
Ó 2015 American Association of Oral and Maxillofacial Surgeons
Surgery, University of Texas Health Science Center, San Antonio, TX.
0278-2391/15/00107-X
Accepted January 26 2015
Address correspondence and reprint requests to Dr Al-Moraissi:
http://dx.doi.org/10.1016/j.joms.2015.01.035
Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Thamar
University,
Thamar,
Redaa
Street,
Yemen;
e-mail:
[email protected]
1
2
BIODEGRADABLE VERSUS TITANIUM FIXATION
Table 1. PICOS CRITERIA FOR THE SYSTEMATIC REVIEW
Patients or population (P)
Intervention (I) Comparator or control group (C) Outcomes (O) Study design (S)
Focused question
All patients 15-50 yr old had jaw deformities diagnosed as mandibular prognathism or retrognathism with or without bimaxillary asymmetry and maxillary hypo- or hyperplasia that required orthognathic surgery (BSSO, Le Fort I or both) Biodegradable (bicortical screws) as poly-L-lactic acid Titanium osteosynthesis Postoperative skeletal relapse (linear and angular measurements) and postoperative wound problems and intraoperative plate and screw fractures Clinical human studies, including randomized controlled trials, controlled clinical trials, or retrospective studies, whose aim was comparing skeletal stability and post- and intraoperative complications between bioresorbable and titanium osteosynthesis for various orthognathic surgical procedures Do biodegradable fixation screws have similar skeletal stability for various orthognathic surgical procedures as titanium osteosynthesis?
Abbreviation: BSSO, bilateral sagittal split osteotomy. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
in which removal is necessary. Fewer operations for removal imply less discomfort for patients. It also can benefit society, because fewer removal operations will put less pressure on the capacity of the health care system and preclude patients from missing more work for the removal surgery.11 Additional advantages of biodegradables are their radiolucency and decreased stress shielding because of a progressive decrease in strength and stiffness during degradation, which can stimulate bone healing.12 There is ongoing search for the ideal fixation system.11 Thus, the authors hypothesized that there is no difference in skeletal stability for various orthognathic surgeries (bilateral sagittal split osteotomy [BSSO], Le Fort I osteotomy, or bimaxillary surgery) using titanium or biodegradable fixation. The specific aims were to compare 1) skeletal stability and 2) material-related problems between titanium and biodegradable fixation systems when used to stabilize orthognathic procedures.
Materials and Methods LITERATURE SEARCH STRATEGY
This systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)E 2012 checklist.13 An electronic search of the PubMed, Ovid MEDLINE, and Cochrane CENTRAL online databases was conducted from their respective dates of inception to December 2014. Free text words and Medical Subject Heading terms were used. The headings bioresorbable screws, titanium osteosynthesis, biodegradable osteofixation, poly-L-lactic acid (PLLA), and orthognathic surgery were combined with skeletal stability or relapse. Articles were sought that compared titanium and biodegradable
fixation systems for patients 13 to 50 years old who underwent orthognathic surgery. The low yield led to the use of another search term omitting the reference to bioresorbable OR biodegradable OR poly-L-lactic acid (PLLA) OR PLLA-PGA OR resorbable screws versus titanium OR nonresorbable OR metal for orthognathic surgery (bilateral sagittal split ramus osteotomy) AND (Le Fort I OR bimaxillary surgery OR mandibular OR maxillary setback OR mandibular OR maxillary advancement OR maxillary impaction OR skeletal Class III malocclusion OR Class II) AND (postsurgical movement OR relapse OR skeletal stability OR plate fracture OR postoperative complication OR material-related complication OR B-point OR prognathism OR long face) AND (limit to OR clinical trial OR randomized controlled trial). The abstracts of yielded results were reviewed and the full text was obtained of those with apparent relevance. The references of identified articles were cross-checked for unidentified articles and the individual databases of key subject journals were searched using the same terms listed earlier. These journals were the Journal of Oral and Maxillofacial Surgery, the International Journal of Oral and Maxillofacial Surgery, the Journal of Oral Surgery, and the British Journal of Oral and Maxillofacial Surgery. The searches were limited to articles published in English. An attempt was made to identify unpublished material or to contact authors of published studies for further information. To complete the search, the references of each selected publication on degradable versus titanium osteosynthesis for orthognathic surgery were manually searched. The PICOS criteria for the study are presented in Table 1. The following exclusion criteria were applied: 1) case reports, 2) technical reports, 3) animal or in vitro studies, 4) review papers, 5) uncontrolled
Patients, n Study
Year of Study Publication Design
M/F Ratio
Age (yr), Mean (Range)
Material of Follow-Up Osteo-Fixation Period
Biod
10
10
Class III malocclusion
BSSO
Ti, PLLA
after 1 yr
20
20
Class II skeletal malocclusion dentofacial deformities
BSSO
Ti, PLLA/PGA
6 mo
1997
CCT
NM
Ferretti and Reyneke15 Cheung et al16
2002
CCT
NM
2004
RCT
Biod + Ti, 22.9 (16-37)
30
30
Norholt et al17 Ueki et al18
2004
RCT
total sample, 9/21 NM
NM
29
28
2005
RCT
NM
NM
20
20
Costa et al19
2006
RS
NM
12
10
Landes and Ballon20
2006
CCT
30
30
Turvey et al21
2006
CCT
total sample, 11/24 total sample, 16/18
Biod + Ti, 27.40 (no range given) 25 (16-57), 23/37
35
34
Ueki et al22
2006
CCT
Ti, 26.8 (no range given); Biod, 27.5 (no range given) Biod + Ti, 22.9 (16-34)
26
21
Landes et al23
2007
RS
Biod + Ti, 27 (18-47)
30
15
Oba et al24
2008
CCT
22
23
Dhol et al25
2008
CCT
25
25
maxillary growth disturbance mandibular prognathism Class III malocclusion. 25 patients Angle Class II, 35 Class III dysgnathia isolated mandibular deficiency
Le Fort I, BSSO, self-reinforced genioplasty PLLA
up to 2 yr
Le Fort I, BSSO
after 1 yr
BSSO
Ti, PGA/PLLA copolymer PLLA
Le Fort I, BSSO
Ti, PLLA/PGA
after 1 yr
Le Fort I, BSSO
Ti, PLLA
after 1 yr
BSSO
self-reinforced $1 yr bone screws placed, Ti
mandibular prognathism Le Fort I, with or without BSSO, IVRO bimaxillary asymmetry Le Fort I, BSSO 25 patients Angle Class II, 35 Class III dysgnathia skeletal mandibular BSSO prognathism
vertical maxillary excess, anterior open bite
Le Fort I
Ti, PLLA miniplate
$1 yr
after 1 yr
Ti, PLGA miniplate
PLLA
$1 yr
Ti, PLLA/PGA miniplate
after 1 yr
3
Biod, Ti, 26.4 (no 10/13; range given); Ti, 10/13 Biod, 22.1 (no range given) Biod, Ti, 22.9 (no 8/17; range given); Ti, 5/20 Biod, 23.3 (no range given)
Type of Orthognathic Surgeries
Ti
Harada and Enomoto14
total sample, 8/39 total sample, 22/23
Ti, 22.4 (20-31); Biod, 23 (18-30) NM
Type of Dentofacial Deformity
AL-MORAISSI AND ELLIS
Table 2. CHARACTERISTICS OF INCLUDED STUDIES
4
Table 2. Cont’d
Patients, n Study
Year of Study Publication Design
M/F Ratio
2010
RCT
Stockmann et al27
2010
RCT
total sample, 30/72 NM
Paeng et al28
2012
CCT
NM
Ballon et al29
2012
CCT
NM
Buijs et al1
2012
RCT
NM
Ueki et al8
2012
CCT
NM
van Bakelen et al3
2013
RCT
van Bakelen et al11
2014
RCT
Ti, 51/73; Biod, 36/39 NM
Landes et al30
2014
RS
NM
Blakey et al31
2014
RS
Ti, 7/20; Biod, 14/16
Ti
Biod
Type of Dentofacial Deformity
maxillary or 26 BSSO, 11 29 BSSO, mandibular growth 17 Le Fort I, BSSO, 10 disturbances 8 bimaxillary bimaxillary 33 33 23 (80%) mandibular retrognathism, 13 (20%) mandibular prognathism Ti, 25.3 (18-33); 25 25 skeletal Class III Biod, 22.6 malocclusion (18-30) Ti, 25 (16-56); 22 41 Class II and III Biod, 24 malocclusion (16-46) 133 84 dentofacial Biod + Ti, 31 deformities (no range given) Biod + Ti, 23.9 20 20 mandibular (16-48) prognathism with maxillary retrognathism Biod + Ti, 31 134 78 dentofacial (no range deformities given) 22 15 mandibular Ti, 35 (19-59); prognathism Biod, 35 (18-59) 25 25 Class II and III Ti, 24 (15-42); malocclusions Biod, 29 (14-56) Ti, 20.8; Biod, 30 27 NM 19.7 Biod + Ti, 33.5 (no range given) Biod + Ti, 27 (no range given)
Type of Orthognathic Surgeries
Material of Follow-Up Osteo-Fixation Period
Le Fort I, BSSO, PLDLA, Ti BIMX
up to 1 yr
BSSO
8 yr
PLLA
BSSO
resorbable bicortical screws BSSO, Le Fort I, PLLA BIMX
17.8 mo
Le Fort I, BSSO, bioresorbable fractures screws
8 wk
Le Fort I, BSSO
PLLA
$1 yr
Le Fort I, BSSO
Biod
2 yr
BSSO
Biod, Ti
2 yr
Le Fort I, BSSO
F-u-HA/PLLA, Ti
after 1 yr
Le Fort I
poly-lactate PLLDL (70:30), Ti
after 1 yr
$1 yr
Abbreviations: BIMX, bimaxillary surgery; Biod, biodegradable; BSSO, bilateral sagittal split osteotomy; CCT, controlled clinical trial; F, female; F-u-HA/PLLA, forged unsintered hydroxyapatite with poly-L-lactide; IVRO, intraoral vertical ramus osteotmy; M, male; NM, not mentioned; PLDLA, poly-L/DL-lactic acid; PLLA/PGA, poly-L-lactic acid and polyglycolic acid; PLLDL, poly-L/DL-lactic; RCT, randomized controlled trial; RS, retrospective study; Ti, titanium. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
BIODEGRADABLE VERSUS TITANIUM FIXATION
Tuovinen et al26
Age (yr), Mean (Range)
Study
Year of Publication
Type of Surgery
Harada and Enomoto14 Bjuis et al1 Ferretti and Reyneke15 Cheung et al16 Norholt et al17
1997 2012 2002
BSSO
Magnitude of Movement (mm)
Relapse (mm)
Significance
BSSO
— — —
— — 0.83 Biod, 0.25 Ti
no statistical difference no statistical difference no statistical difference
2004 2004
Le Fort I Le Fort I
— 2-3 Biod, 2-3 Ti
comparable function no statistical difference
Ueki et al18 Ueki et al22
2005 2006
6.75 Biod, 6.55 Ti 5.75 Biod, 6.25 Ti
Costa et al19
2006
BSSO BSSO + Le Fort I, IVRO + Le Fort I BIMX
— 0.16 Biod, maxilla; 1.33 Biod, mandible; 0.90 Ti, maxilla; 3.19 Ti, mandible comparable 0.2 Biod, 1.4 Ti
Turvey et al21 Landes and Ballon20
2006 2006
BSSO BIMX
3.54 Biod, maxilla; 4.29 Ti, mandible — 3.5 Biod, 5.4 Ti
0.16 Biod, maxilla; 1.33 Biod, mandible; 0.90 Ti, maxilla; 3.35 Ti, mandible comparable 0.2 Biod, 1.4 Ti
Landes et al23
2007
BIMX
2.5 Biod, maxilla; 5.5 Ti, mandible
Dhol et al25 Oba et al24
2008 2008
Le Fort I BSSO
— 9.1 Biod, 7.0 Ti
1.2 Biod, maxilla; 0.8 Biod, mandible; 1.4 Ti, mandible; 34.2 Ti, mandible 0.2 Biod, 1.4 Ti —
Stockmann et al27 Tuovinen et al26 Paeng et al28 Ballon et al29 Ueki et al8 van Bakelen et al11 Lands et al30
2010
BSSO
—
6% Biod, 6% Ti
no statistical difference horizontal maxillary stability inferior to vertical in Biod group bioresorbable fixation is reliable in segment fixation as Ti no statistical difference bioresorbable fixation might be effective in properly selected cases no statistical difference
2010
BSSO, Le Fort, BIMX
—
—
no statistical difference
2012 2012 2012 2014
BSSO BSSO, Le Fort I Le Fort I BSSO
6.7 Biod, 6.7 Ti 4.9 Biod; 1.3 Ti 6 Biod, 6 (15) —
no statistical difference Biod less stable than Ti no statistical difference no statistical difference
2014
Le Fort I, BSSO
Blakey et al31
2014
Le Fort I
Le Fort, 4, 56 Biod, 6.04 Ti; BSSO, 4.64 Biod, 7.30 Ti 5.6 Biod, maxilla; 7.1 Ti, maxilla
comparable — — vertical, 0.03 Biod, 0.3 Ti; horizontal, 0.1 Biod, 0.3 Ti Le Fort, 3, 82 Biod, 3.25 Ti; BSSO, 2.98 Biod, 8.72 Ti —
AL-MORAISSI AND ELLIS
Table 3. TYPES OF ORTHOGNATHIC SURGERY, MAGNITUDE OF MOVEMENTS, RELAPSE, AND SIGNIFICANCE OF OUTCOMES WITHIN INCLUDED STUDIES
no statistical difference no statistical difference no statistical difference
no statistical difference no statistical difference
Abbreviations: BIMX, bimaxillary surgery; Biod, biodegradable; BSSO, bilateral sagittal split osteotomy; Ti, titanium.
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Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
6 — — — — — — Biod, 1; Ti, 2 — — — — — — — — — — — — — — Biod, 3; Ti, 13 — — — Biod, 59; Ti, 43 Biod, 39; Ti, 44 — — — — — — Biod, 2; Ti, 1 Biod, 1; Ti, 2 Biod, 12; Ti, 16
Ti, 3; Biod, 2 Biod more than Ti Ti, 10; Biod, 11 Ti, 3; Biod, 6
22 articles included in qualitative and quantitative synthesis (metaanalysis)
257 articles screened through titles and abstracts
200 articles excluded due to topic-off
35 of records excluded due to they did not meet inclusion criteria
FIGURE 1. Study screening process.
Abbreviations: Biod, biodegradable; Ti, titanium.
Biod, 0; Ti, 0 Biod, 0; Ti, 0 Biod, 0; Ti, 0 Biod, 1; Ti, 0 — Biod, 1; Ti, 0 — Biod, 5; Ti, 0 Biod, 1; Ti, 1 Biod, 0; Ti, 0 Biod, 0; Ti, 0 Biod, 0; Ti, 0 Biod, 2; Ti, 1 Biod, 1; Ti, 0 Biod, 1; Ti, 1 Biod, 1; Ti, 2 Biod, 11; Ti, 4 Biod, 2; Ti, 3 Dhol et al25 Ferretti and Reyneke15 Harada and Enomoto14 Norholt et al17 Paeng et al28 Stockmann et al27 Tuovinen et al26 Buijs et al1 van Bakelen et al3
Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
Biod,7 plates and 72 screws (75% in Le Fort I); Ti, none — — — — Biod, 4; Ti, 0; (screw head) Biod, 5; Ti, 1; (screw head) — — — Ti, 3; Biod, 2 Biod, 3; Ti, 3 Cheung et al16
Infection
Wound Dehiscence
Intraoperative Plate Fractures
Plate Removal
Plating Timing
300 articles excluded due to duplications
57 articles of full text assessed for eligibility
Study
Table 4. COMPLICATIONS AMONG INCLUDED STUDIES
557 of records identified through electronic database and hand searching
Plate Palpability
Sinus Tract
BIODEGRADABLE VERSUS TITANIUM FIXATION
clinical studies, 6) studies that did not report data (mean and standard deviation) required to perform a meta-analysis, and 7) publications in which the same data were published by the same groups of researchers. The authors carefully assessed the eligibility of all studies retrieved from the databases. From the included studies in the final analysis, the following data were extracted: authors, year of publication, study design, gender (male, female), mean age in years, numbers of patients in groups, type of dentofacial deformities, material used for osteosynthesis, follow-up period, and confounding factors (Table 2).1,3,8,11,14-31 The selected articles were used to compare the primary outcome variables and skeletal stability (using cephalometrics) and material-related problems (predictor variables) for orthognathic surgery. A methodologic quality rating was performed by combining the proposed criteria of the Meta-Analysis of Observational Studies in Epidemiology statement (MOOSE),32 the Strengthening the Reporting of Observational Studies in Epidemiology statement (SROSES),33 and the PRISMA34 to verify the strength of scientific evidence in clinical decision making. The classification of risk for bias potential for each study was based on the following 5 criteria: random selection in the population, definition of inclusion and exclusion criteria, report of losses to follow-up, validated measurements, and statistical analysis. A study that included all these criteria
7
AL-MORAISSI AND ELLIS
Table 5. CRITICAL APPRAISAL (QUALITY ASSESSMENT) OF INCLUDED STUDIES
Study Harada and Enomoto14 Ferretti and Reyneke15 Cheung et al16 Norholt et al17 Ueki et al18 Costa et al19 Landes and Ballon20 Turvey et al21 Ueki et al22 Landes et al23 Oba et al24 Dhol et al25 Tuovinen et al26 Stockmann et al27 Paeng et al28 Ballon et al33 Buijs et al1 Ueki et al8 van Bakelen et al3 van Bakelen et al11 Landes et al30 Blakey et al31
Year of Publication
Random Selection in Population
Defined Inclusion and Exclusion Criteria
Loss to Follow-Up
Validated Measurement
Statistical Analysis
Estimated Potential Risk of Bias
1997
no
yes
yes
yes
yes
moderate
2002
no
yes
yes
yes
yes
moderate
2004 2004 2005 2006 2006
yes yes yes yes no
yes yes yes yes yes
yes yes yes yes yes
yes yes yes yes yes
yes yes yes yes yes
low low low low moderate
2006 2006 2007 2008 2008 2010 2010
no no no no no no yes
yes yes yes yes yes yes yes
yes yes yes yes yes yes yes
yes yes yes yes yes yes yes
yes yes yes yes yes yes yes
moderate moderate moderate moderate moderate moderate low
2012 2012 2012 2012 2013
yes no yes no yes
yes yes yes yes yes
yes yes yes yes yes
yes yes yes yes yes
yes yes yes yes yes
low moderate low moderate low
2014
yes
yes
yes
yes
yes
low
2014 2014
no no
yes yes
yes yes
yes yes
yes yes
moderate moderate
Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
was classified as having a low risk of bias, and a study that did not include 1 of these criteria was classified as having a moderate risk of bias. When at least 2 criteria were missing, the study was considered to have a high risk of bias. ANALYSIS OF SELECTED STUDIES
Meta-analyses were conducted only if there were studies of similar comparisons and reporting the
same outcome measurements. For binary outcomes, the authors planned to calculate a standard estimation of risk difference (RR) by the random-effects model if heterogeneity was detected. Otherwise a fixed-effect model with a 95% confidence interval (CI) was performed. Weighted mean difference (WMD) or standard mean difference (SMD; if the studies used different instruments to measure outcomes) was used to construct forest plots of continuous data. In addition, benefit-and-risk analyses were performed in which the
FIGURE 2. Forest plots for the angle formed by the sella, nasion, and B point (degrees; angular measurement; continuous data) after bilateral sagittal split osteotomy using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
8
BIODEGRADABLE VERSUS TITANIUM FIXATION
FIGURE 3. Forest plots for horizontal changes (millimeters; linear measurement; continuous data) after bilateral sagittal split osteotomy using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
number needed to treat, with 95% CIs, was calculated for persistent inferior alveolar nerve disturbances. The data were analyzed using the statistical software Review Manager 5.2.6 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark, 2012).26 For those studies that had heterogeneity of their data, no attempt was made to perform a metaanalysis. The means of surgical movements and relapse were calculated by weighted means (Table 3). Postoperative complications, including infection, wound dehiscence, intraoperative plate fractures, plate removal, plate palpability, plating timing, and sinus tract, were recorded and are presented in Table 4. ASSESSMENT OF HETEROGENEITY
The importance of any discrepancies in the estimates of the treatment effects of the different trials was assessed by the Cochran test for heterogeneity and the I2 statistic, which describes the percentage
of total variation across studies that is due to heterogeneity rather than chance. Heterogeneity was considered statistically significant at a P value less than .1. A rough guide to the interpretation of I2 given in the Cochrane handbook35 is as follows: 1) from 0 to 40%, the heterogeneity might not be important; 2) from 30 to 60%, there might be moderate heterogeneity; 3) from 50 to 90%, there might be substantial heterogeneity; and 4) from 75 to 100%, there is considerable heterogeneity. Ideally, all studies should be performed in the same manner with the same experimental protocols. If not, heterogeneity increases. Heterogeneity refers to the variation in study outcomes between studies. When high, different statistics must be applied (random-effects model).
Results The final number of articles selected according to the initial and final selection criteria are presented in
FIGURE 4. Forest plots for vertical changes (millimeters; linear measurement; continuous data) after bilateral sagittal split osteotomy using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
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AL-MORAISSI AND ELLIS
FIGURE 5. Forest plots for the angle formed by the sella, nasion and A point (degrees; angular measurement; continuous data) after bimaxillary surgery using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
Figure 1. The search strategy resulted in 557 articles on biodegradable versus titanium fixation in orthognathic surgical procedures, namely BSSO, Le Fort I, and bimaxillary surgery (advancement or setback surgery or both). After selection according to the inclusion and exclusion criteria, 22 articles1,3,8,11,14-31 qualified for the final review. Eight studies11,14,15,18,21,24,27,28 compared biodegradable and titanium fixation osteosynthesis after BSSO advancement (6 studies) and setback (2 studies). Thirteen studies1,3,8,16,17,19,20,22,23,26,29-31 compared biodegradable and titanium fixation osteosynthesis after bimaxillary surgery in which BSSO and Le Fort I osteotomies was performed for advancement or setback (according to the deformities). Two studies25,31 examined isolated Le Fort I maxillary surgery, 1 examined maxillary impactions,25 and 1 examined maxillary advancement.31 Twenty studies8,11,14-31 assessed the postoperative stability between biodegradable and titanium fixation. Ten studies1,3,14-17,25-28 compared intraoperative and postoperative complications after various orthognathic surgeries when using biodegradable or titanium fixation. Ten studies were controlled clinical trials,14,15,21,22,24,25,28,29 8 were randomized controlled trials,1,3,16-18,25-27 and 4 were retrospective studies.19,23,30,31 Concerning the quality assessment of the included studies, 10 studies1,3,11,16-19,27,28 showed a low risk of bias and 13 studies8,14,15,20-26,29,31 showed a moderate risk of bias. The scores are listed in Table 5.
RESULTS OF INDIVIDUAL VARIABLES
Skeletal Stability BSSO—biodegradable versus titanium osteosynthesis. Angular measurement—sella, nasion, and B point (degrees). Three studies8,18,28 of 130 patients (titanium, n = 65; biodegradable, n = 65) compared changes in the angle formed by the sella, nasion, and B point after BSSO at follow-up periods ranging from 12 to 17.8 months. There was no significant difference between the 2 groups (random: WMD = 0.03 ; 95% CI, 0.38 to 0.44 mm; P = .88). The test of heterogeneity among all studies showed homogeneity (c2 = 1.57; df = 2; P < .46; I2 = 0%; Fig 2). Linear measurements—horizontal changes in millimeters. Eight studies11,14,15,18,21,24,28,30 of 338 patients (biodegradable, n = 171; titanium, n = 167) compared horizontal skeletal changes after BSSO at follow-up periods ranging from 6 months to 1 year. There was no significant difference between the 2 groups, but the result still favored the titanium group (random: SMD = 0.11 mm; 95% CI, 0.52 to 0.30; P = .59). The test of heterogeneity among all studies showed heterogeneity (c2 = 91.56; df = 14; P < .001; I2 = 85%); therefore, a random-effects model was used (Fig 3). Linear measurements—vertical changes in millimeters. Six studies8,11,14,21,24,30 of 225 patients (biodegradable, n = 110; titanium, n = 115) compared vertical skeletal changes after BSSO at follow-up periods to 1 year. There was no significant
FIGURE 6. Forest plot for occlusal cant (millimeters; angular measurement; continuous data) after bimaxillary surgery using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
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BIODEGRADABLE VERSUS TITANIUM FIXATION
FIGURE 7. Forest plot for horizontal changes (millimeters; angular and linear measurements; continuous data) after bimaxillary surgery using biodegradable versus titanium osteosynthesis. CI, confidence interval; IV, inverse variance; SD, standard deviation. Al-Moraissi and Ellis. Biodegradable Versus Titanium Fixation. J Oral Maxillofac Surg 2015.
difference between the 2 groups, but the results still favored the titanium group (random: SMD = 0.06 mm; 95% CI, 0.44 to 0.31; P = .74). The test of heterogeneity among all studies showed heterogeneity (c2 = 48.75; df = 11; P < .001; I2 = 77%); therefore, a random-effects model was used (Fig 4). Bimaxillary surgery—biodegradable versus titanium osteosynthesis. Angular measurement—sella, nasion, and A point (degrees). Three studies8,19,22 of 86 patients (titanium, n = 44; biodegradable, n = 42) compared changes in the angle formed by the sella, nasion, and A point after bimaxillary surgery at follow-up periods of 1 year. There was no significant difference between the 2 groups, but the results favored the titanium group (random: WMD = 0.95 ; 95% CI, 1.98 to 0.08 mm; P = .07). The test of heterogeneity among all studies showed homogeneity (c2 = 0.20; df = 2; P < .91; I2 = 0%; Fig 5). Angular measurement—occlusal cant in millimeters. Three studies8,17,22 of 119 patients (titanium, n = 60; biodegradable, n = 59) compared occlusal canting after bimaxillary surgery at follow-up periods of 1 year. There was no significant difference between the 2 groups (random: WMD = 0.17 ; 95% CI, 1.86 to 1.53 ; P = .84). The test of heterogeneity among all studies showed heterogeneity (c2 = 36.20; df = 2; P
