|Year : 2020 | Volume
| Issue : 4 | Page : 258-265
Comparison of strengths of five internal fixation methods used after bilateral sagittal split ramus osteotomy: An in vitro study
Farzin Sarkarat1, Atiye Ahmady2, Farzam Farahmand2, Ali Fateh3, Roozbeh Kahali1, Amir Nourani4, Vahid Rakhshan2
1 Department of Oral and Maxillofacial Surgery; Craniomaxillofacial Research Center, Islamic Azad University of Medical Sciences, Tehran, Iran
2 Private Practice, School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
3 Craniomaxillofacial Research Center, Islamic Azad University of Medical Sciences, Tehran, Iran
4 Department of Mechanical Engineering, School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
|Date of Web Publication||14-Aug-2020|
Dr. Farzin Sarkarat
#4, Neyestan 10th, Pasdaran Ave., Tehran
Source of Support: None, Conflict of Interest: None
Background: Results on the strength and displacement of internal fixation methods for bilateral sagittal split ramus osteotomy are controversial, and some designs have not been adequately studied. Therefore, this study was conducted to compare techniques using bicortical or monocortical screws.
Materials and Methods: In this in vitro study, 35 sheep hemi-mandibles were randomly assigned to five groups of seven each: fixation using (1) a 13 × 2 screw, (2) two 13 × 2 screws (arranged vertically), (3) three 13 × 2 screws, (4) 1 plate with 4 holes and four monocortical screws, and (5) a Y-shaped plate and five monocortical screws. Specimens underwent vertical forces until failure. Breakage forces and displacements of groups were recorded and compared statistically. Using one-way analysis of variance (ANOVA) with a Tukey's post hoc test and Kruskal–Wallis test. Level of significance was predetermined as 0.05.
Results: Strengths of Groups 1–5 were, respectively, 14.43 ± 4.35, 28.00 ± 8.89, 28.29 ± 8.01, 29.43 ± 8.24, and 61.29 ± 12.38 N, respectively (P = 0.000, analysis of variance). The corresponding displacement extents were 7.98 ± 0.04, 7.85 ± 0.26, 8.00 ± 0.00, 7.35 ± 1.73, and 6.79 ± 2.03 mm (P = 0.298, Kruskal–Wallis test).
Conclusion: Use of a single bicortical screw is the weakest method, while Y-shaped plates might provide the highest strength. Using two or three bicortical screws or 4-hole plates might deliver similar strengths.
Keywords: Bone plates, fracture fixation, internal, sagittal split ramus osteotomy, surgical fixation devices
|How to cite this article:|
Sarkarat F, Ahmady A, Farahmand F, Fateh A, Kahali R, Nourani A, Rakhshan V. Comparison of strengths of five internal fixation methods used after bilateral sagittal split ramus osteotomy: An in vitro study. Dent Res J 2020;17:258-65
|How to cite this URL:|
Sarkarat F, Ahmady A, Farahmand F, Fateh A, Kahali R, Nourani A, Rakhshan V. Comparison of strengths of five internal fixation methods used after bilateral sagittal split ramus osteotomy: An in vitro study. Dent Res J [serial online] 2020 [cited 2021 Mar 8];17:258-65. Available from: https://www.drjjournal.net/text.asp?2020/17/4/258/292061
| Introduction|| |
Bilateral sagittal split ramus osteotomy (BSSRO) is commonly practiced and benefitted from a broad contact between the osteotomized segments, allowing a sufficient and accurate contact, and enhancing stability and repair. The osteotomized sections should be fixed in order to allow repair to occur; they can be successfully fixed with various techniques and tools such as metal plates and/or screws,,,, namely stable internal fixation which is positioned in direct contact with the bone, enabling it to function during repair, which reduces the need for maxillomandibular blocks.,, This technique needs varying sizes and types of instruments such as positional or compressive screws, monocortical plates, or their combination.,,,,
However, there are cases in which bicortical screws are not advisable; these include extreme advancements of the mandible, or asymmetrical mandibular motions, which might decrease the bone contact between the osteotomized segments. Although less severe cases can be managed by grafting or compensatory wear and tear, severe extents of mandibular movement might be the cases of using altered designs such as plates and monocortical screws (or a combination of mono- and bi-cortical screws), which might have some advantages; for example, they are easier to install/correction/removal, do not need skin incisions, can exert smaller torques to the proximal segment, and reduce the probability of neurovascular damage.,,,
Various combinations of plates and screws have been compared inin vitro studies,,,,,, which have shown controversial results. Moreover, some designs have not been studied adequately. Therefore, thisin vitro study was conducted to comparatively evaluate the strength and displacement of five different designs of internal fixations in BSSRO of sheep mandibles.
| Materials and Methods|| |
In this experimentalin vitro study, 35 hemimandibles of sheep (aged between 1 and 2 years old with an average of 1.7 years) were obtained and cleaned off all soft tissues. The sample size was predetermined as five groups of seven specimens each (based on the results of the study of Olivera et al.).
Jaws were obtained in frozen and complete form. Their sizes and widths were subjectively checked to be similar. Each jaw was dissected into two left and right hemimandibles from the mandibular symphysis. BSSRO was performed using the standard method in order to move the anterior segment for 5 mm. The specimens were randomly assigned to five fixation groups of seven specimens each: in Group 1, fixation of osteotomy was performed using a 13 × 2 screw placed 20 mm above the mandibular border (taking into account the intra-alveolar canal) and 5 mm posterior to the osteotomy site [Figure 1] and in Group 2, fixation was performed using two 13 × 2 screws (in a vertical linear formation, 10 mm away) positioned 20 and 30 mm above the mandibular border and 5 mm posterior to the osteotomy [Figure 2]. In Group 3, fixation was performed using three 13 × 2 screws at least 5 mm posterior to the osteotomy site, at least 20 mm above the mandibular border, and 10 mm away from each other [Figure 3]. In Group 4, monocortical fixation was performed using 1 plate with 4 holes which was screwed onto the mandible 20 mm above its border, using four 9 × 2 screws [Figure 4]. In Group 5, monocortical fixation was carried out using a Y-shaped plate 20 mm above the border, using five 9 × 2 screws [Figure 5]. Fixations were done with titanium pieces (Behin Ideh Ortoped, Tehran, Iran).
About 7 mm superior to the gonial angle, two 5-mm holes 10 mm away from each other (vertically) were drilled in order to be able to fix the specimens to the testing machine (Zwick Roell, Amsler HCT 25-400, Ulm, Germany). The specimens were attached to the machine, using a metal support in a way that the occlusal plane of the hemimandible and the horizontal plane of the machine were aligned parallel. In the area of force application, the hemimandible was supported so that the power cell did not slip and there could be no errors when performing the test. Testing was performed by exerting a progressive vertical force on the second molar [Figure 6] until failure and breakage of the fixation or fractures occur through the mandible [Figure 7]. At the end, the maximum values of the registered forces in the groups as well as their corresponding displacements were measured and reported. In case the specimen did not break, a force equal to 8 mm of displacement would be recorded. The failure threshold was considered as 8 mm displacement. Cases with <8 mm displacement which had fractures were considered unsuccessful as well.
Descriptive statistics and 95% confidence intervals (CI) were calculated for force and distribution values of each group. Kolmogorov–Smirnov test was used to check the normality of data. Data regarding force were normally distributed, but displacement data did not follow a normal distribution. Therefore, data force values of five groups were compared using one-way analysis of variance (ANOVA) with a Tukey's post hoc test. Displacement values were compared using a Kruskal–Wallis test and a Dunn post hoc test (in the case if there is significance of Kruskal–Wallis test). Level of significance was predetermined as 0.05.
| Results|| |
The average extents of displacement of all groups except Y-shaped plates were above 7 mm. The average force was similar in the groups “2 screws, 3 screws, and 4-hole plates” around 28 and 29 N. The average force of the group “1 screw” was half of this extent. On the other hand, the average force of Y-shaped plates was about twice larger than the average of the mentioned three groups. Detailed descriptive statistics and 95% CIs are presented in [Table 1].
|Table 1: Descriptive statistics and 95% confidence intervals for breakage force and displacement values|
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ANOVA showed a significant difference between the five force groups (P = 0.000). Tukey's test showed that there were significant differences between all groups, except between specimens fixed with 2 screws versus those fixed with 3 screws, specimens fixed with 2 screws versus those fixed with 4-hole plates, and specimens fixed with 3 screws versus those fixed with 4-hole plates [Table 2] and [Figure 8]. Comparison of displacement data using Kruskal–Wallis test did not show a significant difference between the five groups (P = 0.298).
|Figure 8: Boxplots presenting nonparametric descriptive statistics for breakage forces (N).|
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| Discussion|| |
In this study, the strengths of five types of mandibular split osteotomy fixation in sheep mandibles were compared in vitro. According to the results, all of the fixation techniques succeeded to provide proper stability and strength in the mandible following the application of vertical forces (both in terms of the strengths against the forces and the amount of displacements of fixed parts). However, the highest strength values were found to be in the Y-shaped plate fixation method (mean 61.29 N), which was significantly higher than all the other fixation methods. Furthermore, the least strength values against force application were observed in fixation with 1 screw (mean 14.43 N), which was significantly lower than other fixation methods. On the other hand, fixations with 2 screws, 3 screws, and 4-hole plates had similar breakage strengths. These observations were in line with displacement extents, with the Y-shaped fixation method having the highest strength values, also showing the least displacement (average displacement of 6.79 mm), although no overall significant difference was observed between the methods, probably because of the maximum limit of 8 mm imposed in the measurement of displacement. In order for the fixation or bone to fail, a sudden drop in the biomechanical resistance might be needed. In some specimens, the applied forces increased gradually and the displacement occurred without reaching the maximum force values, hence no failure. In such specimens, the final displacement (at 8 mm) was considered as the point of failure. Nonetheless, the 8-mm displacement might not accord with clinical evidence; Ardary et al. argued that the range of failure should be considered to be 1 mm, instead of the currently mentioned value of 8 mm.In vitro biomechanical tests are a useful tool for evaluating the strength of fixations and the extent of displacement of osteosynthesis materials before their clinical applications. Although the anatomy of sheep or cow mandible differs from that of human mandible, they can provide high reproducibility, they are economic, their resistance might not change by months of freezing, and their use is one of the best options.,,,,, To simulate the effects of human osteotomy on the sheep's mandible, changes to the surgical protocol should be made, such as the medial inclination of the incision and the incision under the mandibular foramen. However, it should be taken into account that the data obtained from biomechanical tests combined with the use of bone-like human bones cannot be used directly for clinical applications in humans. Obviously, further clinical studies should be undertaken to verify their results. In addition, in many clinical situations, the surgeon might chose the fixation method based on other factors such as the type of displacement (advance, asymmetry, and rebound) and its extent, as well as the balance between the proximal and distal segments or the type of fracture.
The use of positional screws is the most common method for fixation of sagittal osteotomy. On the other hand, the use of monocortical screws and plates for fixation of sagittal osteotomy has become very common in recent years, and with appropriate results.,,,, Furthermore, the use of plates with bicortical screws is also recommended.,,,, The rigidity and strength of linear systems fixed using bicortical positional screws might be stronger compared to that of miniplate systems with quadruple screws., Furthermore, some studies have reported that fixation with bicortical screws has more resistance to displacement.,,
The usage of bicortical screws may pose a risk of damage to the lingual nerve, while monocortical systems might least likely damage the nerve. Still, some surgeons prefer bicortical screws because of lower stability, strength, breakage resistance, and rigidity of plates fixed using monocortical screws and their lower resistance to breakage.,,,,, This can be due to the smaller involvement of the bone and/or the smaller surface area of the miniplate exerting a greater pressure. On the other hand, in some studies, the fixation stability of the microplate has been reported as similar to that of bicortical fixation,,, which might be attributed to methodological differences such as the demographics of the samples or techniques of measurements, or the expertise of the surgeons. Recent meta-analyses have shown that skeletal stability obtained by bicortical screws might not differ from miniplate fixation., It seems that even the lower strengths of miniplates might suffice to endure clinical stresses because the masticatory forces are much weaker in the recovery period right after the surgery.
A method for increasing the biomechanical strength of fixations is the use of 4-hole miniplates, in which there are two proximal holes fixed with bicortical screws and two distal holes with monocortical screws. Ozden et al. showed that the use of this technique has a greater resistance compared to miniplates fixed with monocortical screws. In the present study, fixation with a 4-hole plate yielded breakage strength comparable to those of using 2 or 3 screws, which was a different protocol from that of Ozden et al. Our findings were in line with those of Atik et al. who showed that 4-hole plates could provide adequate stability compared to other fixation models. On the other hand, findings of Albougha et al. do not agree with these research; instead, they indicated that miniplates with T and Y forms had the greatest von Mises stress levels. Sarkarat et al. reported that parallel miniplates and 4-hole plates might have the highest stability values, while single screws and 2-hole miniplates had the lowest resistance to posterior forces. This was consistent with the findings of this study. Our results regarding the relative weakness of single-screw fixations were in line with the research of Bohluli et al., Hammer et al., and Sarkarat et al., who demonstrated that single-screw could have the least resistance to breakage. In the present study, breakage forces were similar in fixations using 2 or 3 screws or using 4-hole plates. As well, Olivera et al. did not find significant differences between three methods of reverse L pattern with 3 screws, a hybrid of a plate and 4 screws, and two plates fixed using 8 screws.
This study was limited by some factors. In single-screw fixation, the segment should torque or rotate on the axis of screw, which is not a determinant for the strength, while in two or more point fixation, fracture of bone/screw or plate should occur. This was a constraint of all such studies. Although the sample size was predetermined based on a previous study, larger samples could allow detection of more failures and therefore a better estimation of skeletal strength. Moreover, pure vertical forces applied in allin vitro studies (like Nieblerova et al.) cannot reflect clinical conditions, with mandible movements rapidly changing in magnitude and direction, against which the fixation device should resist. In addition, generalizability of this and similar designs is limited because we have checked the strength under vertical forces only, but BSSO segments are also prone to horizontal and multidirectional stresses in clinical conditions. It should be noted that in clinical conditions, factors such as muscle strength, diet, or demographics as well as surgical protocol and matching the segments can play crucial roles. The distance from the osteotomy site to the area of force application can influence the recorded maximum values of the registered forces. It is better to apply the forces on the occlusal surface instead of a point, if technically possible. The minimum–maximum ranges of the measured forces were very large. However, it was mostly due to outliers because the variations existing in the data were reasonable, as indicated by coefficients of variation.
| Conclusion|| |
Within the limitations of this study, it was concluded that using a single bicortical screw for fixation of BSSO might be the weakest method, while using the Y-shaped plate attached with monocortical screws could provide the highest strength among the assessed techniques. The use of 2 or 3 bicortical screws or 4-hole plates and monocortical screws might provide similar strengths.
Financial support and sponsorship
The study was self-funded by the authors.
Conflicts of interest
The authors of this manuscript declared that they have no conflicts of interest, real or perceived, and financial or nonfinancial in this article.
| References|| |
Olivera LB, Sant' Ana E, Manzato AJ, Guerra FL, Arnett GW. Biomechanicalin vitro
evaluation of three stable internal fixation techniques used in sagittal osteotomy of the mandibular ramus: A study in sheep mandibles. J Appl Oral Sci 2012;20:419-26.
Hammer B, Ettlin D, Rahn B, Prein J. Stabilization of the short sagittal split osteotomy:In vitro
testing of different plate and screw configurations. J Craniomaxillofac Surg 1995;23:321-4.
Rubens BC, Stoelinga PJ, Blijdorp PA, Schoenaers JH, Politis C. Skeletal stability following sagittal split osteotomy using monocortical miniplate internal fixation. Int J Oral Maxillofac Surg 1988;17:371-6.
Shetty V, Freymiller E, McBrearty D, Caputo AA. Functional stability of sagittal split ramus osteotomies: Effects of positional screw size and placement configuration. J Oral Maxillofac Surg 1996;54:601-9.
Uckan S, Schwimmer A, Kummer F, Greenberg AM. Effect of the angle of the screw on the stability of the mandibular sagittal split ramus osteotomy: A study in sheep mandibles. Br J Oral Maxillofac Surg 2001;39:266-8.
Ellis E 3rd
, Dean J. Rigid fixation of mandibular condyle fractures. Oral Surg Oral Med Oral Pathol 1993;76:6-15.
Stoelinga PJ, Borstlap WA. The fixation of sagittal split osteotomies with miniplates: The versatility of a technique. J Oral Maxillofac Surg 2003;61:1471-6.
Blomqvist JE, Ahlborg G, Isaksson S, Svartz K. A comparison of skeletal stability after mandibular advancement and use of two rigid internal fixation techniques. J Oral Maxillofac Surg 1997;55:568-74.
Watzke IM, Tucker MR, Turvey TA. Lag screw versus position screw techniques for rigid internal fixation of sagittal osteotomies: A comparison of stability. Int J Adult Orthodon Orthognath Surg 1991;6:19-27.
Schwartz HC, Relle RJ. Bicortical-monocortical fixation of the sagittal mandibular osteotomy. J Oral Maxillofac Surg 1996;54:234-5.
Turvey TA. Resorbable osteosynthesis in orthognathic surgery. J Oral Maxillofac Surg 2006;64:18-9.
Tulasne JF, Schendel SA. Transoral placement of rigid fixation following sagittal ramus split osteotomy. J Oral Maxillofac Surg 1989;47:651-2.
Shetty V, Freymiller E, McBrearty D, Caputo AA. Experimental analysis of functional stability of sagittal split ramus osteotomies secured by miniplates and position screws. J Oral Maxillofac Surg 1996;54:1317-24.
Peterson GP, Haug RH, Van Sickels J. A biomechanical evaluation of bilateral sagittal ramus osteotomy fixation techniques. J Oral Maxillofac Surg 2005;63:1317-24.
Ozden B, Alkan A, Arici S, Erdem E.In vitro
comparison of biomechanical characteristics of sagittal split osteotomy fixation techniques. Int J Oral Maxillofac Surg 2006;35:837-41.
Foley WL, Beckman TW.In vitro
comparison of screw versus plate fixation in the sagittal split osteotomy. Int J Adult Orthodon Orthognath Surg 1992;7:147-51.
Van Sickels JE, Flanary CM. Stability associated with mandibular advancement treated by rigid osseous fixation. J Oral Maxillofac Surg 1985;43:338-41.
Bohluli B, Motamedi MH, Bohluli P, Sarkarat F, Moharamnejad N, Tabrizi MH, et al.
Biomechanical stress distribution on fixation screws used in bilateral sagittal split ramus osteotomy: Assessment of 9 methods via finite element method. J Oral Maxillofac Surg 2010;68:2765-9.
Sarkarat F, Motamedi MH, Bohluli B, Moharamnejad N, Ansari S, Shahabi-Sirjani H, et al.
Analysis of stress distribution on fixation of bilateral sagittal split ramus osteotomy with resorbable plates and screws using the finite-element method. J Oral Maxillofac Surg 2012;70:1434-8.
Ardary WC, Tracy DJ, Brownridge GW 2nd
, Urata MM. Comparative evaluation of screw configuration on the stability of the sagittal split osteotomy. Oral Surg Oral Med Oral Pathol 1989;68:125-9.
Bouwman JP, Tuinzing DB, Kostense PJ. A comparativein vitro
study on fixation of sagittal split osteotomies with würzburg screws, champy miniplates, and biofix (biodegradable) rods. Int J Oral Maxillofac Surg 1994;23:46-8.
Suuronen R, Pohjonen T, Vasenius J, Vainionpää S. Comparison of absorbable self-reinforced multilayer poly-l-lactide and metallic plates for the fixation of mandibular body osteotomies: An experimental study in sheep. J Oral Maxillofac Surg 1992;50:255-62.
Ueki K, Nakagawa K, Takatsuka S, Yamamoto E. Plate fixation after mandibular osteotomy. Int J Oral Maxillofac Surg 2001;30:490-6.
Assael LA, Prein J. Stable internal fixation of osteotomies of the facial skeleton. Manual of Internal Fixation in the Cranio-Facial Skeleton. Berlin, Germany: Springer Berlin Heidelberg; 1998. p. 185-98.
Van Sickels JE, Peterson GP, Holms S, Haug RH. Anin vitro
comparison of an adjustable bone fixation system. J Oral Maxillofac Surg 2005;63:1620-5.
Murphy MT, Haug RH, Barber JE. Anin vitro
comparison of the mechanical characteristics of three sagittal ramus osteotomy fixation techniques. J Oral Maxillofac Surg 1997;55:489-94.
Pereira FL, Janson M, Sant'Ana E. Hybrid fixation in the bilateral sagittal split osteotomy for lower jaw advancement. J Appl Oral Sci 2010;18:92-9.
Anucul B, Waite PD, Lemons JE.In vitro
strength analysis of sagittal split osteotomy fixation: Noncompression monocortical plates versus bicortical position screws. J Oral Maxillofac Surg 1992;50:1295-9.
Matsushita Y, Nakakuki K, Kosugi M, Kurohara K, Harada K. Does intraoral miniplate fixation have good postoperative stability after sagittal splitting ramus osteotomy? Comparison with intraoral bicortical screw fixation. J Oral Maxillofac Surg 2016;74:181-9.
Fujioka M, Fujii T, Hirano A. Comparative study of mandibular stability after sagittal split osteotomies: Biocortical versus monocortical osteosynthesis. Cleft Palate Craniofac J 2000;37:551-5.
Ochs MW. Bicortical screw stabilization of sagittal split osteotomies. J Oral Maxillofac Surg 2003;61:1477-84.
Sato FR, Asprino L, Noritomi PY, da Silva JV, de Moraes M. Comparison of five different fixation techniques of sagittal split ramus osteotomy using three-dimensional finite elements analysis. Int J Oral Maxillofac Surg 2012;41:934-41.
Fujioka M, Hirano A, Fujii T. Comparative study of inferior alveolar disturbance restoration after sagittal split osteotomy by means of bicortical versus monocortical osteosynthesis. Plast Reconstr Surg 1998;102:37-41.
Sato FR, Asprino L, Consani S, de Moraes M. Comparative biomechanical and photoelastic evaluation of different fixation techniques of sagittal split ramus osteotomy in mandibular advancement. J Oral Maxillofac Surg 2010;68:160-6.
Chuong CJ, Borotikar B, Schwartz-Dabney C, Sinn DP. Mechanical characteristics of the mandible after bilateral sagittal split ramus osteotomy: Comparing 2 different fixation techniques. J Oral Maxillofac Surg 2005;63:68-76.
Hu J, Zhao Q, Tang J, Zheng Z, Qi MC. Changes in the inferior alveolar nerve following sagittal split ramus osteotomy in monkeys: A comparison of monocortical and bicortical fixation. Br J Oral Maxillofac Surg 2007;45:265-71.
Choi BH, Min YS, Yi CK, Lee WY. A comparison of the stability of miniplate with bicortical screw fixation after sagittal split setback. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;90:416-9.
Kabasawa Y, Sato M, Kikuchi T, Sato Y, Takahashi Y, Higuchi Y, et al.
Analysis and comparison of clinical results of bilateral sagittal split ramus osteotomy performed with the use of monocortical locking plate fixation or bicortical screw fixation. Oral Surg Oral Med Oral Pathol Oral Radiol 2013;116:e333-41.
Al-Moraissi EA, Al-Hendi EA. Are bicortical screw and plate osteosynthesis techniques equal in providing skeletal stability with the bilateral sagittal split osteotomy when used for mandibular advancement surgery? A systematic review and meta-analysis. Int J Oral Maxillofac Surg 2016;45:1195-200.
Al-Moraissi EA, Ellis E. Stability of bicortical screw versus plate fixation after mandibular setback with the bilateral sagittal split osteotomy: A systematic review and meta-analysis. Int J Oral Maxillofac Surg 2016;45:1-7.
Atik F, Atac MS, Özkan A, Kılınc Y, Arslan M. Biomechanical analysis of titanium fixation plates and screws in sagittal split ramus osteotomies. Niger J Clin Pract 2016;19:140-4.
] [Full text]
Albougha S, Darwich K, Darwich MA, Albogha MH. Assessment of sagittal split ramus osteotomy rigid internal fixation techniques using a finite element method. Int J Oral Maxillofac Surg 2015;44:823-9.
Nieblerová J, Foltán R, Hanzelka T, Pavlíková G, Vlk M, Klíma K, et al.
Stability of the miniplate osteosynthesis used for sagittal split osteotomy for closing an anterior open bite: An experimental study in mini-pigs. Int J Oral Maxillofac Surg 2012;41:482-8.
Khosravanifard B, Rakhshan V, Araghi S, Parhiz H. Effect of ascorbic acid on shear bond strength of orthodontic brackets bonded with resin-modified glass-ionomer cement to bleached teeth. J Dent Res Dent Clin Dent Prospects 2012;6:59-64.
Rues S, Lenz J, Türp JC, Schweizerhof K, Schindler HJ. Forces and motor control mechanisms during biting in a realistically balanced experimental occlusion. Arch Oral Biol 2008;53:1119-28.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
[Table 1], [Table 2]