Bone-borne Device Research Articles

In-silico evaluation of orthodontic miniscrew-assisted rapid palatal expanders for patients with various stages of skeletal maturation

This study aimed to use a finite element method to assess the stress on the miniscrews, skeletal and dental changes resulting from maxillary expansion using either a tooth-bone-borne (TBB) or a bone-borne (BB) device on patients with various skeletal maturation. Two types of expanders were modeled using SolidWorks. The design of the 2 expanders was similar, with the exception that the BB appliance lacked support for teeth (rods and bands). Both were placed on the palatal bones with the help of 4 miniscrews as bony anchorage. Five skeletal maturation stages were examined using suture maturation classification by Angelieri. A lateral displacement of 0.2 mm was applied to simulate 1 turn of jackscrew per day. The dental and skeletal changes from the treatment were quantified. Stage A sutural maturation exhibited the greatest skeletal movement (0.13 mm/d) with a V-shaped displacement pattern. Stages B and C exhibited a more parallel expansion pattern. Stages D and E exhibited the least amount of skeletal movement with either device. Compared with the BB device, TBB demonstrated greater dental displacement. On average, the BB device exhibited a skeletal-to-dental expansion ratio of 70% from stage A to C compared with 49% with the TBB device. BB device showed more skeletal displacement than TBB, and the latter showed more dental side effects, particularly during stages B and C. The miniscrew-assisted rapid palatal expansion appliance was effective with sutural maturation stages A to C using the classification by Angelieri with a more parallel separation of the midpalatal sutures in stages B and C.

Comparison of the effects of different rapid maxillary expansion techniques on craniofacial structures: a finite element analysis study

AimTo compare the effects of three different maxillary expansion appliances with five different types of expansion modalities on stress distribution and displacement on the maxilla and its adjacent craniofacial structures using the finite element method (FEM).Materials and methodsCone-beam computed tomography data of a patient with maxillary transverse deficiency were rendered into a three-dimensional model of craniomaxillary structures. The expansion appliances included tooth-borne, hybrid, and bone-borne expanders. Five different expansion modalities were applied to each expander [conventional Rapid Maxillary Expansion (RME) (type 1), midpalatal suture cortico-puncture-assisted RME (type 2), LeFort l cortico-puncture-assisted RME (type 3), surgically assisted RME (SARME) without pterygomaxillary junction (PMJ) separation (type 4), and SARME with bilateral PMJ separation (type 5)]. The numerical and visual data were analyzed.ResultsThe highest amount of stress accumulation on teeth was found in the tooth-borne and hybrid groups. On the other hand, more stress concentration on the maxilla was observed in the bone-borne group. SARME cuts with PMJ separation increased total movement by reducing the stress on the midpalatal suture in all groups. While types 1, 2, and 3 were similar in terms of the amounts of displacement, types 4 and 5 increased the total amount of displacement in all groups. The total amounts of displacements from the highest value to the lowest value for the anterior and posterior maxilla were in the bone-borne, tooth-borne, and hybrid groups.ConclusionsSARME cuts were effective in reducing stress on the teeth, but the cortico-puncture application affected neither the stress values on the teeth nor the transverse displacement in the tooth-borne expanders. Surgical procedures such as SARME and corticotomy should be used with bone-borne devices to improve the outcomes of maxillary expansion procedures.

Short-Term and Long-Term Changes of Nasal Soft Tissue after Rapid Maxillary Expansion (RME) with Tooth-Borne and Bone-Borne Devices. A CBCT Retrospective Study.

The objective of the study was to assess the changes in nasal soft tissues after RME was performed with tooth-borne (TB) and bone-borne (BB) appliances. Methods. This study included 40 subjects with a diagnosis of posterior cross-bite who received tooth-borne RME (TB, average age: 11.75 ± 1.13 years) or bone-borne RME (BB, average age: 12.68 ± 1.31 years). Cone-beam computed tomography (CBCT) was taken before treatment (T0), after a 6-month retention period (T1), and one year after retention (T2). Specific linear measurements of the skeletal components and of the soft-tissue region of the nose were performed. All data were statistically analyzed. Results. Concerning skeletal measurements, the BB group showed a greater skeletal expansion of the anterior and posterior region of the nose compared to the TB group (p < 0.05) immediately after RME. Both TB and BB RME induce a small increment (>1 mm) of the alar base and alar width, without significant differences between the two expansion methods (p > 0.05). A high correlation was found between skeletal and soft-tissue expansion in the TB group; instead, a weaker correlation was found in the BB group. Conclusion. A similar slight increment of the alar width and alar base width was found in both TB and BB groups. However, the clinical relevance of these differences, in terms of facial appearance, remains questionable.

Comparison of Tooth- and Bone-Borne Appliances on the Stress Distributions and Displacement Patterns in the Facial Skeleton in Surgically Assisted Rapid Maxillary Expansion-A Finite Element Analysis (FEA) Study.

The aim of this study was to compare the reduced stresses according to Huber’s hypothesis and the displacement pattern in the region of the facial skeleton using a tooth- or bone-borne appliance in surgically assisted rapid maxillary expansion (SARME). In the current literature, the lack of updated reports about biomechanical effects in bone-borne appliances used in SARME is noticeable. Finite element analysis (FEA) was used for this study. Six facial skeleton models were created, five with various variants of osteotomy and one without osteotomy. Two different appliances for maxillary expansion were used for each model. The three-dimensional (3D) model of the facial skeleton was created on the basis of spiral computed tomography (CT) scans of a 32-year-old patient with maxillary constriction. The finite element model was built using ANSYS 15.0 software, in which the computations were carried out. Stress distributions and displacement values along the 3D axes were found for each osteotomy variant with the expansion of the tooth- and the bone-borne devices at a level of 0.5 mm. The investigation showed that in the case of a full osteotomy of the maxilla, as described by Bell and Epker in 1976, the method of fixing the appliance for maxillary expansion had no impact on the distribution of the reduced stresses according to Huber’s hypothesis in the facial skeleton. In the case of the bone-borne appliance, the load on the teeth, which may lead to periodontal and orthodontic complications, was eliminated. In the case of a full osteotomy of the maxilla, displacements in the buccolingual direction for all the variables of the bone-borne appliance were slightly bigger than for the tooth-borne appliance.

Resident Commentary: Is There a Significant Difference in Relapse and Complication Rate of Surgically Assisted Rapid Palatal Expansion Using Tooth-Borne, Bone-Borne, and Orthodontic Mini-Implant-Borne Appliances (Ploder et al, 2020)?

Resident Commentary: Is There a Significant Difference in Relapse and Complication Rate of Surgically Assisted Rapid Palatal Expansion Using Tooth-Borne, Bone-Borne, and Orthodontic Mini-Implant-Borne Appliances (Ploder et al, 2020)?

The impact of tooth-borne vs computer-guided bone-borne rapid maxillary expansion on pain and oral health–related quality of life: A parallel cohort study

The primary aim of this study was to investigate and compare perceived pain intensity and oral health-related quality of life (OHRQOL) results during the activation phase of rapid maxillary expansion (RME), with tooth-borne and bone-borne devices. In addition, a secondary aim of this study was to evaluate the correlation between pain scales and the shortened Oral Health Impact Profile (OHIP-14) questionnaire. Thirty-six subjects (16 girls and 20 boys) with a mean age of 12.3years (standard deviation, 0.82years) were randomized into 2 groups. Group A received treatment with hyrax appliance, and group B received a computer-guided skeletal RME appliance. The same type of expansion screw and screw activation or expansionprotocol were used. Two rating scales were used to assess the subject's pain during the activation phase of RME: a Graphic Rating Scale for Pain (GRS) and the Wong-Baker Faces Pain Scale (FPS). The OHIP-14 was used to evaluate the impact of RME on OHRQOL before the beginning of the treatment at day 3 and day 7 follow-ups. Painkillers were forbidden during the active phase of RME. Descriptive statistics, Student t test, and Pearson correlation were used. Significance was set at P≤0.05. A total of 36 subjects, divided into 2 groups, were treated in the study. Regarding the level of pain, the Student t test showed statistically significant higher pain in group B-although only on the first day of screw activation (GRS, P=0.01; FPS, P<0.01). For the following days, there were no significant differences in pain levels between groups. The OHIP-14 showed no statistically significant difference at baseline (P=0.32) and day 3 (P=0.88) and day 7 (P=0.85) follow-ups between the 2 groups. The Pearson correlation coefficient showed a statistically significant association between the 2 different scales of pain (GRS and FPS) but not a statistically significant correlation between GRS and FPS scales and OHIP-14. A higher perceived pain intensity in the patients treated using a bone-borne computer-guided skeletal RME appliance was limited to the first day of screw activation. There were no statistically significant differences between the 2 types of treatment in terms of their impact on OHRQOL and no statistically significant correlation between pain scales and the OHIP-14 questionnaire.

Tooth-borne versus bone-borne rapid maxillary expansion for transverse maxillary deficiency: A systematic review

The aim of this study was to compare dentoskeletal effects of bone-borne expanders with those of conventional expanders in adolescent and adults having transverse maxillary deficiency. All randomized clinical trials (RCTs) comparing the effects of bone-borne with those of tooth-borne expansion for treatment of maxillary transverse deficiency in adults and adolescents with maxillary transverse deficiency or posterior crossbite were included. The systematic search was irrespective of language and publication type. The electronic search was conducted from 1980 to January 2018. The electronic searches retrieved 713 references after screening for eligibility criteria. Eight studies met the inclusion criteria for this systematic review involving 289 participants. Four studies compared rapid maxillary expansion (RME) between bone-borne and tooth-borne devices and indicated effectiveness of both devices on maxillary expansion. In the first molar region, there was no significant difference between two devices in either skeletal or dental expansion. Two studies compared the effects of bone-borne and tooth-borne device following SARME and suggested no significant difference regarding amount and pattern of expansion at various levels and in molar and premolar region between two groups. Two studies compared bone-borne and tooth-bone-borne devices. Within the limit of the present evidence regarding maxillary expansion, it seems that both tooth-borne and bone-borne devices result in the same outcome in terms of the amount of maxillary expansion, dental tipping, stability and perceived pain both in RME and SARME procedure. PROSPERO registration: CRD42017061078.

Expansión rápida maxilar en pacientes adultos jóvenes: comparación de aparatos dentosoportados y esqueletalmente soportados. Estudio de cohorte.

Introduction: Maxillary constrictions are one of the most frequent abnormalities, regardless of the type of dentition studied. They can be treated either with tooth-borne or bone-borne expander appliances, depending on the biological maturation of the patient. Treatment during prepubertal stages has been shown to be successful, but there is evidence of an open suture even in late adolescence stages. The aim of this study is to compare the effects of a rapid expansion bone-borne device to a tooth-borne device in young adults suffering from maxillary constriction, by means of Cone-Beam Computed Tomography. Materials and methods: A retrospective observational study was conducted in nine patients (three males, six females) with a mean age of 18±5.5 years, who attended the Dentistry Service of Universidad de Chile during 2014-2015. Six patients were treated with tooth-borne appliances (Hyrax type) and three patients with bone-borne appliances (MARPE). Linear measurements of the anterior and posterior transverse dimension and angular measurements of the inclination of molars and incisors were obtained through CBCT for each group in T1 and T2. Results: A significant increase in the posterior transverse dimensions in both groups was observed. Radiolucency of the suture was observed in all patients treated with miniscrews and in half of the patients treated with Hyrax. Greater angulation of molars was shown in the tooth-borne group in comparison with the bone-borne group. Conclusion: Both appliances caused an increase in the posterior transverse dimension, but bone anchored appliances achieved a more parallel and skeletal expansion. Randomized clinical trials with a larger sample and follow-up are needed.

TAD Retained Acrylic Palatal Expander for Sarpe

The TAD retainer acrylic Palatal Expander (TAPE) is presented as a method of distracting cases for patients undergoing Surgically Assisted Rapid Palatal Expansion (SARPE). It is simple to fabricate, applies forces entirely to the alveolus, avoids direct dental expansion, and is well tolerated by patients as it is easy to clean and its low profile is comfortable. Surgically, it shares the advantage with Bone Borne Devices that the appliance is not in place while the maxilla is cut and segmented; thereby this allows the surgeon control that the maxillae are separated and moving equally. Orthodontic therapy can also be started at any time unlike tooth bone appliances.

Extensiometric analysis of strain in craniofacial bones during implant-supported palatal expansion.

Palatal expansion has several orthodontic and orthopedic applications, such as increasing maxillary transverse dimensions and correcting maxillary atresia, oral breathing, and skeletal cross-bites. Little is known about the strain to which craniofacial bones are submitted when a palatal expander is loaded. The objectives of the present work were to propose a new palatal bone-borne titanium device (expansion screw), to determine patterns of strain distribution in craniofacial bones during palatal expansion and to show the clinical results of a new palatal expander supported by implants. For in vitro testing, the palatal expander supported by two commercially pure titanium (cp Ti) implants was inserted parallel to the median palatine suture of four dry adult human skulls. Uniaxial and triaxial strain gauges were attached to craniofacial bones and connected to a signal acquisition system. An expansion screw was turned and strain data were collected during palatal expansion. The results showed that the bone strain distribution in craniofacial bones loaded by the palatal bone-borne titanium device was complex: the strain was tensile in the palatine cortical bone and compressive in pterygopalatine processes, nasal bones, and orbital floor. The maximum compressive strain occurs in the upper portion of the pterygopalatine processes and the strain changes from compressive to tensile in the zygomatic process. The experimental results suggest that the bone strain due to the palatal expander is distributed over all craniofacial bones and that the upper portions of pterygopalatine processes are the main sites of resistance to palatal expansion. The new palatal expander supported by two cp Ti implants proposed was employed on adult patient as an illustrative report, where adequate palatal expansion was achieved. The new protocol proposed was less invasive, risky, painful and costless for the correction of moderate maxillary transverse deficiency.

Changes in transverse tooth and bone dimensions during transversal maxillary hypoplasia treatment by maxillary distraction osteogenesis using a device installed on a bone

Abstract Introduction A transverse maxillary hypoplasia is a deformation often observed in orthodontic patients. Various techniques are used to treat this problem. Aim The aim is to present results of transversal maxillary hypoplasia treatment with a bone-borne device. Material and methods A retrospective analysis included 27 patients, age 17–26 years (17 ± 2.6). Dental casts and X-ray were made before operation period (T1), and post distraction (T2). On the casts were determined points: on cusps of maxillary canines (3-3), first maxillary premolars (4-4) and first maxillary molars (6-6). Angles and distances were measured on standard posterior-anterior (PA) images. Results and discussion At the 3-3 level, the average expansion was 5.8 mm, at the 4-4 level the average expansion was 7.3 mm, at the level of 6-6 palatial cusps the average expansion was 6.11 mm. Measurements in the PA X-ray were performed at the nasal cavity, with the average dimensions being 29.03 mm before treatment, and 31.95 mm post-treatment. The angle was measured between first molars (6-6_ang) and the anterior nasal spine before and after treatment, with a significant change in that angle from 98.93° on average to 102.89° after distraction. Conclusions Use of maxillary distraction osteogenesis with bone-borne device in maxillary expansion is an effective treatment method. Maxillary expansion results in increase of the nasal cavity. Used distractor is easy to operate for the patient.

One-stage tooth-borne distraction versus two stage bone-borne distraction in surgically assisted maxillary expansion (SARME)

To evaluate and compare the effects of tooth-borne and bone-borne distraction devices in surgically assisted maxillary expansion (SARME) on dental and skeletal structures. A sample of 33 skeletally mature patients with transverse maxillary deficiencies was examined with cone beam computed tomography (CBCT) before and 3 months after surgery. Fourteen patients were treated with tooth-borne devices and 19 patients with bone-borne devices. Dental crown expansion in the first premolars did not differ significantly between the two groups, and median expansion was 5.55 mm (interquartile range [IQR] 5.23) in the tooth-borne device group and 4.6 mm (IQR 3.4) in the bone-borne device group. In the first molars, crown expansion and lateral tipping were significantly greater in the tooth-borne device group (P ≤ .02). The median skeletal nasal isthmus increase was significantly more in the bone-borne device group at 3.0 mm than in the tooth-borne device group at 0.98 mm (P ≤ .02). Both tooth-borne and bone-borne devices are effective treatment modalities to correct maxillary transverse deficiencies. Bone-borne devices produced greater widening of the skeletal nasal floor and fewer dental side effects in the first molars.

Transpalatal distraction for the management of maxillary constriction in pediatric patients.

Context:The management of severe maxillary constriction can be challenging. For that purpose surgically assisted maxillary expansion by transpalatal distraction (TPD) can typically be recommended after skeletal maturity. However in selected cases bone borne transpalatal distraction devices can contribute to improve maxillary constriction considerably earlier already during mixed dentition.Aims:To assess the possibility of bone borne transpalatal distraction in pediatric patients.Settings and Design:Clinical paper.Materials and Methods:Since 2010 TPD has been applied to six pediatric patients during mixed dentition when severe maxillary constriction was present and conventional orthodontic widening has already failed. Individually selected devices (Surgitec, Belgium) were inserted in general anaesthesia and distraction was performed according to well known parameters.Results:Maxillary constriction could be improved in all six patients without any drawbacks by bone borne devices during mixed dentition. Skeletal conditions were obviously improved for subsequent orthodontic or orthognathic therapy without functional impairment. Follow-up is up to 36 months after device removal.Conclusions:Transpalatal Distraction is recommendable in selected pediatric patients if massive growth disturbance is present or has to be expected. TPD allows for individually adapted maxillary expansion by selection and positioning of appropriate devices in combination with intraoperative testing of maxillary movements and controlled bone removal.

Abstracts of the IBRA Conference on Surgery of the Head, 6th International Orthognathic Surgery Forum, February 14-15, 2014, Interlaken, Switzerland.

The multi-step treatment of severe dentofacial deformities starts after the termination of skeletal bone growth. In cases of additional transversal discrepancies the SARPE procedure has to be executed at first, followed by the orthodontic alignment of the dental arches. Then the at least three step treatment starts: it consists of the pre- and postoperative orthodontic treatment and the treatment in between surgical correction. This combined treatment may last up to three years and longer. For economic reasons as well as for an increasing motivation of the patient the ‘Surgery First’ concept was developed to reduce treatment time. We take advantage of the Regional Acceleration Procedure (RAP), which is known since Kole published the interdental corticotomy in the crowded lower front to accelerate the orthodontic alignment in the 1950s. Instead of hyrax screws for transversal widening we prefer he application of bone borne devices for SARPE procedures. Fixed appliances treatment starts earlier using RAP effect. Instead of preoperative orthodontic treatment we start with the operation and align the dental arches postoperatively within 6-8 months. Advantages of ‘Surgery First’: • The patient sees the operative results immediately. • Orthodontic treatment is accelerated by RAP effect. • Treatment is completed after 6-8 months, sometimes after 10 months. Disadvantages of ‘Surgery First’: • Orthodontists must be experienced and needs to plan the treatment in advance. • More close cooperation between surgeon and orthodontist is needed. • Orthodontic treatment starts 1-2 weeks after the operation with intervals of two weeks. • RAP effect takes three to four months. The ‘Surgery First’ concept can be performed easily with stable results in Angle Class II and III cases with crowding, frontal compensation and pronounced Spee curve. (Segmented) Bimaxillary osteotomies with or without CWR or CCWR can be performed with additional procedures as chin correction or jaw bone augmentation. The ‘Surgery First’ concept delivers safe results also in open bite cases, elongated front regions, minor transversal discrepancies and asymmetries. In cases of severe facial deformities and transversal discrepancies ‘Surgery First’ cannot be recommended yet.

Short-term skeletal and dental changes following bone-borne versus tooth-borne surgically assisted rapid maxillary expansion: A randomized clinical trial study

AimTo evaluate and compare the short-term (post-retention) skeletal and dental changes following bone-borne and tooth-borne surgically assisted rapid maxillary expansion (SARME) using cone beam computed tomography (CBCT). Subjects and methodsIn this randomized clinical study, 30 patients with transverse maxillary deficiency underwent either tooth-borne (n = 15) or bone-borne (n = 15) SARME. Before treatment and immediately after the consolidation period, CBCT was obtained and the nasal floor width, interdental root distance, palatal bone width and interdental cusp distance were measured at first premolar and first molar regions of maxilla. ResultsTwenty eight patients completed the study protocol. In both tooth-borne (n = 13) and bone-borne (n = 15) groups the highest degree of expansion occurred in the dental arch, followed by palatal bone, and nasal floor (V-shaped widening in coronal dimension). The amount and pattern of expansion was comparable between anterior and posterior maxillary regions in each group (parallel posteroanterior expansion) and between the two groups. ConclusionDental and skeletal effects of tooth-borne and bone-borne devices were comparable. The overall complication rate was negligible. Selection of an expansion device should be based on each individual patient's requirements. Future long-term clinical trial studies to evaluate the stability and relapse of these two techniques are recommended.

Volumetric changes of the nose and nasal airway 2 years after tooth‐borne and bone‐borne surgically assisted rapid maxillary expansion

This study aimed to assess the effects of bone-borne and tooth-borne surgically assisted rapid maxillary expansion on the volumes of the nose and nasal airway 2 yr after maxillary expansion. This prospective cohort study included 32 patients with transverse maxillary hypoplasia. Expansion was performed with a tooth-borne distractor (Hyrax) in 19 patients and with a bone-borne distractor [transpalatal distractor (TPD)] in the remaining 13. Cone beam computed tomography scans and three-dimensional (3D) photographs of the face were acquired before treatment and 22 ± 7 months later, and were used to evaluate the volumes of the nose and nasal airway. Nasal volume increased by 1.01 ± 1.6% in the Hyrax group and by 2.39 ± 2.4% in the TPD group. Nasal airway volume increased by 9.7 ± 5.6% in the Hyrax group and by 12.9 ± 12.7% in the TPD group. Changes in the nasal volume and in the nasal airway volume between the pre- and post-treatment measurements were statistically significant, whereas differences between the treatment groups were not; 22 months after surgically assisted rapid maxillary expansion, the increases in the nasal volume and in the nasal airway volume were comparable between tooth-borne and bone-borne devices.

One-Step Transversal Palatal Distraction and Maxillary Repositioning

Transversal maxillary hypoplasia in adolescence is a frequently seen pathology, which can be treated with a combination of surgery and orthodontic treatment to widen the maxilla in skeletally matured patients.We evaluated the advantages of a new surgical technique: Le Fort I distraction osteogenesis using a bone-borne device. Because relapse is one of the main problems in surgical maxillary expansion, long-term stability of this new technique was evaluated. Data from 4 adult patients with maxillary restriction, class III malocclusion, or maxillary malposition were collected preoperatively, 4 months after distraction, and 5 years after distraction. Measurements were recorded on dental models to detect palatal expansion at dental level; cephalograms by lateral and posteroanterior plane were analyzed to detect maxillary movements. Maxillary measurements were substantially stable 5 years after distractions. Only minor dental movements occurred at the dental analysis after 5 years related to a lack of orthodontic contention without any compromise of the dental result (no crossbite relapse and class I stability). Le Fort I with down-fracture for expansion and repositioning by bone-borne distractor device can [corrected] be used to simultaneously widen, advance, and vertically reposition the maxilla without causing healing problems, particularly using a rigid distraction device. Long-term stability can be achieved; however, further studies with a larger number of patients will be necessary for better evaluation.

Assessment of Surgically Assisted Rapid Maxillary Expansion Regarding Pterygomaxillary Disjunction Using Thin Volume-Rendering Technique: In Variance Analysis and in Reliability, Accuracy, and Validity

To assess surgically assisted rapid maxillary expansion (SARME) with or without pterygomaxillary disjunction using a thin volume-rendering technique in variance analysis and in reliability, accuracy, and validity. Thin volume-rendered images of 68 patients were evaluated preoperatively and 2.87 ± 1.59 months after expansion with respect to dentoskeletal effects. Variance analysis of SARME with pterygomaxillary disjunction showed an important decrease in transverse widening and segmental outward inclination and an increase in vestibular bone plate thickness (premolars) in patients younger than 20 years with bone-borne devices; the greatest increase in transverse widening was in patients with 3-segment osteotomy and tooth-borne devices. Analysis of SARME without pterygomaxillary disjunction showed an important decrease in transverse widening and segmental inward inclination in patients older than 20 years with bone-borne devices; the greatest pterygoid lateral bending was in patients with 2-segment osteotomy and bone-borne devices. The performance of pterygomaxillary disjunction should depend on patient age (ie, treatment with pterygomaxillary disjunction in those >20 years old; treatment without pterygomaxillary disjunction in those <20 years old). Patients with pterygomaxillary disjunction, 3-segment osteotomy, and tooth-borne devices tended to show an increase in transverse widening but at the price of greater attachment loss. Patients younger than 20 years with pterygomaxillary disjunction and bone-borne devices tended to show an increase in vestibular bone plate (premolars) but at the price of decrease in transverse widening.

Analysis of the performance of different orthodontic devices for mandibular symphyseal distraction osteogenesis

The aim of this study was to investigate the performance of different orthodontic devices for mandibular symphyseal distraction osteogenesis (MSDO). Two performance parameters were analysed, the first of which concerned the stability guaranteed by a distractor in the fracture gap under mastication loads and the second the level of reliability with which a distractor transfers a given expansion to the mandibular bone, inasmuch as the more reliable the device the smaller the difference between the degree of expansion provided to the device and the displacement achieved on the mandibular arch. Hence, a non-linear finite element (FE) model of a human mandible with different devices (tooth-borne, bone-borne, and hybrid) was constructed and then utilized to assess the structural behaviour of the mandibular bone under distraction and mastication loads. An ad hoc algorithm was developed to simulate progressive expansion of the devices; a distraction protocol comprising a 10 day latency period and a 6 day distraction period was hypothesized. The first hypothetical expansion given to the device was 2 mm, and the five subsequent expansions were 1 mm. The results showed that the hybrid device was the most stable appliance under mastication loads, followed by the tooth- and bone-borne devices. However, parasitic rotations of the mandibular arms caused by mastication might counteract the benefits of distraction. The tooth-borne device was found to have the highest reliability in transferring expansion to the mandibular bone. For this device, mandibular expansion was less than the nominal aperture of the distractor by no more than 15 per cent. Lower values of reliability were achieved with the bone-borne device. As the values of the aperture of the appliances increased, the stability guaranteed in the fracture gap increased while the reliability in transferring expansion to the mandibular arch decreased.

Prostaglandin E2 levels in gingival crevicular fluid during tooth- and bone-borne expansion

The purpose of this study was to compare Prostaglandin E(2) (PGE(2)) levels in gingival crevicular fluid (GCF) of young adults with maxillary constriction during tooth- and bone-borne expansion. Thirty patients, 15 females and 15 males, with a mean age of 17.3 +/- 2.8 years were divided into three groups. Group I consisted of 10 patients, five females and five males, treated by transpalatal distraction (TPD) as a bone-borne device, group II 10 patients, five females and five males, with a Hyrax appliance as a tooth-borne device, and a control group of 10 patients, five females and five males, without any expansion appliances. GCF samples were collected with filter paper strips at six observation periods in order to evaluate the effect of heavy orthopaedic forces in both groups. In group II, the samples were additionally collected at two pre-treatment time points in order to evaluate the effect of the forces generated by the separators. An automated enzyme immunoassay was used to measure PGE(2) in the GCF. The differences within the groups were evaluated with a pairwise t-test and the differences between the groups were determined by the Mann-Whitney U-test. The mean PGE(2) level was significantly elevated on day 4 after placement of the separators in group II (P < 0.05). The PGE(2) values in group II were significantly different to those in group I and the controls at all observation periods. Lower PGE(2) levels were observed in group I compared with group II and the controls. Expansion using the TPD method could potentially enhance the prognosis of the teeth by inducing more skeletal dental changes when compared with the Hyrax appliance.