Bone Borne Research Articles

Treatment of severe skeletal Class III patient with buccally impacted canines and severe crowding using a bone-anchored facemask and Alt-RAMEC protocol: A case report

A 14-year-10-month-old female patient presented with a chief complaint of being dissatisfied with the looks of her teeth and face. She had a pronounced misalignment of her dentition, defined by a Class III skeletal relationship and an average vertical proportion of the face. The patient had an anterior crossbite and bilateral posterior crossbites, with the upper left canine impacted in a buccal position. After a comprehensive consultation with the patient and her parents, we decided to implement a treatment strategy that entailed utilizing a maxillary bone borne expander in conjunction with a facemask. This treatment followed a protocol that consisted of alternating between rapidly expanding and contracting the maxilla. The purpose of this was to stimulate the advancement of the midface. After the treatment was carried out to treat the crossbites, a fixed appliance (MBT prescription) was bonded on the maxillary and mandibular arches. In addition, four premolars were extracted, and the upper left canine was brought to occlusion. Temporary anchorage devices were used in the lower arch to provide skeletal anchorage. The patient underwent active treatment for a period of 24 months following which we were able to achieve satisfactory occlusal and esthetic results.

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.

Pediatrics, Craniofacial and Orthognathic Surgery Track: Use of a Bone Borne Palatal Distractor for Maxillary Expansion: A 20-year Single Surgeon Retrospective

Pediatrics, Craniofacial and Orthognathic Surgery Track: Use of a Bone Borne Palatal Distractor for Maxillary Expansion: A 20-year Single Surgeon Retrospective

External root resorption and rapid maxillary expansion in the short-term: a CBCT comparative study between tooth-borne and bone-borne appliances, using 3D imaging digital technology

BackgroundThe aim of the study was to analyze and compare external root resorption (ERR) in patients treated with tooth-borne (TB) and bone-borne (BB) rapid maxillary expansion (RME).MethodsThe sample included 40 subjects who received tooth-borne RME (TB group, average age: 13.1 ± 1.08 years) or bone-borne RME (BB group, average age: 14.5 ± 1.11 years) and Cone-beam computed tomography (CBCT) scans before treatment (T0) and after 3-month of retention (T1). A specific 3D Imaging technology was used to generate 3D models of posterior dentition (M1 = maxillary first molars, P2 = second premolars, P1 = first premolar) and calculate volumetric data (mean and percentage values) and shape changes, the latter obtained from deviation analysis between the radicular models at different time points. Evaluation of radicular length changes was performed for each tooth. Data were statistically analysed to perform intra-timing and inter-groups comparisons.ResultsA significant reduction of radicular volume and length was found in posterior dentition in both groups (p < 0.05), and the M1 (volume) and its palatal root (length) were mostly involved in this response. No differences were found between M1, P1 and P2 (p > 0.05) when volumetric changes were calculated as percentage of the total volume. Deviation analysis revealed that the radicular areas mostly affected by shape change were the apex and bucco-medial side. The amount of ERR was significantly greater in TB group compared to BB group.ConclusionsBB-RME treatment could reduce the amount of ERR at the post-expansion stage.

External root resorption (ERR) and rapid maxillary expansion (RME) at post-retention stage: a comparison between tooth-borne and bone-borne RME

BackgroundThe study aimed to compare external root resorption (ERR) three-dimensionally in subjects treated with tooth-borne (TB) versus bone-borne (BB) rapid maxillary expansion (RME). Forty subjects who received tooth-borne RME (TB group, average age 13.3 years ± 1.10 years) or bone-borne RME (BB group, average age 14.7 ± 1.15 years) were assessed using CBCT imaging before treatment (T0) and after a 6-month retention period (T1). 3D reconstructions of the radicular anatomy of maxillary first molars (M1), first and second premolars (P1 and P2) were generated to calculate volumetric (mean and percentage values) and shape changes (deviation analysis of the radicular models) obtained at each time point. 2D assessment of radicular length changes was also performed for each tooth. Data were statistically analyzed to perform intra-group (different teeth) and inter-group comparisons.ResultsIn both groups, all the investigated teeth showed a significant reduction in radicular volume and length (p < 0.05), with the first molars being the teeth most affected by the resorption process (volume and palatal root length). When volumetric radicular changes were calculated as a percentage of the pre-treatment volumes, no differences were found among the investigated teeth (p > 0.05). Based on the deviation analysis from radicular models superimposition, the areas most affected by shape change were the apex and bucco-medial root surface. Overall, the amount of ERR was significantly greater in the TB group (mm3: M1 = 17.03, P1 = 6.42, P2 = 5.26) compared to the BB group (mm3: M1 = 3.11, P1 = 1.04, P2 = 1.24).ConclusionsDespite the statistical significance, the difference in the amount of ERR of the posterior maxillary dentition between TB-RME and BB-RME remains clinically questionable.

Nasal Septum Changes in Adolescents Treated with Tooth-Borne and Bone-Borne Rapid Maxillary Expansion: A CBCT Retrospective Study Using Skeletal Tortuosity Ratio and Deviation Analysis.

Using three-dimensional (3D) images, this study evaluated the impact of Rapid Maxillary Expansion (RME) on changes in Nasal Septal Deviation (NSD). Cone-beam computed tomography (CBCT) scan of 40 children with transverse maxillary deficiency, who received tooth-borne (TB) RME or bone-borne (BB) RME, were included in this investigation. Two CBCT scans were performed: one before to appliance installation (T0) and one after a 6-month retention period (T1). The analysis was performed by dividing the actual length of the septum by the desired length in the mid-sagittal plane to measure NSD based on the tortuosity ratio (TR). Subjects in the TB group showed a statistically significant reduction (p &lt; 0.05) of the TR value from T0 to T1, according to the paired Student t test. Subjects in the BB group showed similar findings, with a statistically significant reduction (p &lt; 0.05) of the TR value from T0. No statistically significant differences were found between the mean changes of TR between TB group and BB group. RME may have some effects in reducing the degree of NSD; however, no differences were found between RME performed with TB and BB anchorage systems.

Virtual surgical planning of inferior alveolar nerve microsurgery and benign pathology of the mandible: case reports

: With the aid of virtual surgical planning (VSP) software as well as 3-dimensional printing technology, custom surgical guides can be created utilizing the pre-operative data of patients, including both computed tomography and intraoral scans. VSP technology allows for the customization of surgical guides which can provide an array of benefits that aid in improving patient care. Surgical guides can be designed as occlusal borne, bone borne, or a combination of the two. Though an intraoral scan is beneficial to bolster surgical guide accuracy, it is not necessary, as demonstrated in the following case presentations. This manuscript will demonstrate the use of custom occlusal and bone borne surgical guides that were used for access to the inferior alveolar nerve for exploratory microsurgery as well as two cases necessitating removal of benign pathology within the mandible. Surgical guides aid in improving intraoperative efficiency, in decreasing operating time and in reducing potential surgical trauma. Overall, we expect a decrease in morbidity due to the more predictable nature of guided surgeries. The use of custom surgical guides allows for a more precise and conservative osteotomy, thereby decreasing morbidity. The more efficient and predictive nature of guided surgery aids in patient recovery and surgical outcomes, as well.

THE EFFICIENCY OF TOOTH-ANCHORED VERSUS BONEANCHORED RAPID MAXILLARY EXPANSION IN YOUNG AND LATE ADOLESCENT PATIENTS

Relevance of the problem. Incidence of posterior cross­bite has been reported to be 8–23% and it is a com­mon problem often seen in children and adolescents. An effective treatment of the skeletal transversal maxillary deficiency usually involves rapid maxillary expansion (RME). The expansion can be achieved using different types of expanders: bone anchored, tooth anchored or hybrid. The variety of clinical results comparing bone-borne and tooth-borne RME influence lack of unanimous treatment plan for adolescents. Aim. To compare the efficiency of tooth-borne expanders with bone-borne expanders by comparing dentoskeletal changes evaluated by CBCT. Material and methods. Electronic database search was carried out according to PRISMA principles. Five electro­nic research databases were searched including Medline (via PubMed), Cochrane Library, ProQuest, Wiley On­line Library and Web of Science. PICOS framework was used to form a focused question and the risk of bias was assessed using the Cochrane tool for randomized trials (RoB 2) by two individual researchers. Included studies were randomized clinical trials, published less than 10 years ago, with minimum follow-up period of 9 months with CBCT. Results. Two studies proved that bone borne RME produ­ced greater results in skeletal expansion, however other two studies failed to confirm these findings. Regarding alveolar bone loss, the results were also contradictory: two studies found no significant difference in both RME groups, however, other two studies found that bone borne RME exhibit less alveolar bone loss. As for den­tal tipping, the results were also different in all studies: In a study performed by Lagravere et al (2013), dental tipping occurred regardless of RME treatment for molar teeth, however in the premolar group, increased tipping was noticed in the tooth-anchored group. Another study by the same author concluded similar results: in the to­oth borne RME group no significant tipping in molars was seen, while in premolars, buccal crown tipping was observed, which was significant (p&lt;0.003). In the bone borne RME group significant dental tipping was obser­ved in molars. Contrary to these findings, two studies concluded that dental tipping is experienced significantly less in the bone-borne RME group and one study per­formed by Davami et al found no significant difference in both groups. Conclusion. To conclude, current evidence suggests contradictory results in maxillary expansion using bone borne or tooth borne RME devices. Though the evidence is limited, both types of RME have similar outcomes. More studies with a higher number of patients are nee­ded to determine conclusive results.

Three-dimensional assessment of palatal area changes after posterior crossbite correction with tooth-borne and tooth bone-borne rapid maxillary expansion.

To assess and compare the three-dimensional treatment changes in palatal surface area and volume using either tooth-borne (TB) or tooth bone-borne (TBB) rapid maxillary expanders and to evaluate the long-term effects of the two devices and the incidence of the relapse between the groups. A total of 52 consecutive patients who met the eligibility criteria were recruited and allocated to either the TB group, mean age 9.3 years (standard deviation [SD], 1.3), or the TBB group, mean age 9.5 years (SD, 1.2). Study casts were taken before, directly after, 1 year after, and 5 years after expansion. Study casts were digitized, superimposed, and evaluated. Participants were randomly allocated in blocks of different sizes using the concealed allocation principle in a 1:1 ratio. Changes in palatal volume, palatal surface area, and palatal projection area within and between the groups up to 5 years after expansion followed the same pattern and did not show any statistically significant differences between the groups. Relapse was seen in 15% of the patients. It seemed that open-bite and a Class III growth pattern could be assumed as prognosis-deteriorating factors in regard to stability of the treatment. There were no significant differences between the TB and TBB groups in palatal volume, palatal shell area, or palatal projection area directly after expansion or at 1 year and 5 years after expansion, which implies that the two devices gave rise to the same immediate and long-term outcomes.

Three-dimensional comparison of bone-borne and tooth-bone-borne maxillary expansion in young adults with maxillary skeletal deficiency.

To compare the transverse dental and skeletal changes in patients treated with bone-anchored palatal expander (bone-borne, BB) compared to patients treated with tooth and bone-anchored palatal expanders (tooth-bone-borne, TBB) using cone-beam computer tomography (CBCT) and 3D image analysis. The sample comprised 30 patients with transverse maxillary discrepancy treated with two different types of appliances: bone-borne (Group BB) and tooth-bone-borne (Group TBB) expanders. CBCT scans were acquired before (T1) and after completion of maxillary expansion (T2); the interval was 5.4 ± 3.4 and 6.2 ± 2.1months between the T1 and the T2 scans of Group TBB (tooth-bone-borne) and Group BB (bone-borne), respectively. Transverse, anteroposterior and vertical linear and angular three-dimensional dentoskeletal changes were assessed after cranial base superimposition. Both groups displayed marked transverse skeletal expansion with a greater ratio of skeletal to dental changes. Greater changes at the nasal cavity, zygoma and orbital levels were found in Group BB. A relatively parallel sutural opening in an anterior-posterior direction was observed in Group TBB; however, the Group BB presented a somewhat triangular (V-shaped) opening of the suture that was wider anteriorly. Small downward-forward displacements were observed in both groups. Asymmetric expansion occurred in approximately 50% of the patients in both groups. Greater skeletal vs dental expansion ratio and expansion of the circummaxillary regions were found in Group BB, the group in which a bone-borne expander was used. Both groups presented skeletal and dental changes, with a similar amount of posterior palate expansion. Asymmetric expansion was observed in both groups.

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.

Evaluation of the effects of different rapid maxillary expansion appliances on airway by acoustic rhinometry: A randomized clinical trial

ObjectiveThe purpose of this 3-arm parallel trial was to compare the effects of tooth tissue-borne (TTB), tooth-borne (TB) and bone-borne (BB) rapid maxillary expansion (RME) appliances on nasal airway with acoustic rhinometry (AR). Setting and sample populationForty-six 12- to 14-year-old patients with narrow maxilla were randomly allocated into 3 study groups accordingly the type of expander: TTB, TB and BB. The participants were recruited from the Department of Orthodontics, Izmir Katip Celebi University. Materials and methodsAll patients had RME with an initial activation of two-quarter turns a day (0.5 mm) for an average of 8 days followed by 1 quarter turns per day for an average of 10 days. Disguised group allocation using opaque sealed envelopes was made with a computer-generated randomization program. The primary outcome was changes on the minimal nasal cross-sectional area (MCA). Secondary outcome included the assessment of nasal cavity volume. AR measurements were obtained at baseline (T0), immediately after the expansion (T1), and at 3 months-follow-up (T2). One-way analysis of variance (ANOVA) and Bonferroni test were used for inter-group comparison and two-way ANOVA was used for intra-group evaluation. ResultsThere were significant increases in MCA 1, 2 and nasal Vol in all groups after the treatment (95% [CI], P < 0.05) whereas in inter-group comparisons; MCA 1, 2 and nasal Vol, the changes were found to be similar (95% [CI], P > 0.05). HarmsNo serious harm was observed except for mild gingivitis due to plaque accumulation. ConclusionsRME treatment increased minimal nasal cross-sectional areas and nasal volume irrespective of appliance design. Trial registrationThis trial was registered at Clinicaltrials.gov (Identifier NCT04529057). ProtocolThe protocol was not published. FundingThis trial was financed by Izmir Katip Celebi University, Scientific Research Projects Unit [grant number 2016-TDR-SABE-0024].

MARPE

Contracted maxillary arch has always been a major concern to those who have interested themselves in regulation of teeth. Rapid expansion of maxilla by forceful separation has been discussed in orthodontic literature revealing considerable controversy over the desire and possibility of splitting the hard palate at the midsagittal suture as a mean of widening the dental arch and nasal cavity. Incorporation of mini screws in a conventional RPE appliance transforms it into a MARPE appliance. Mini screws ensure maximum skeletal expansion, keeping the dental expansion and resultant side effects to a minimum. Various designs have been recommended by authors around the globe; exclusively bone borne, teeth-bone borne and tissue-bone borne with two/ four mini screws in the assembly. Paramedian area 3 mm lateral to the suture in 1st premolar region is considered the most appropriate site for placement of mini screws. Anterior screws are placed in the rugae area while posterior screws in the para-midsagittal area.

Geometry of anchoring miniscrew in the lateral palate that support a tissue bone borne maxillary expander affects neighboring root damage

Anchoring miniscrews used for a tissue bone borne maxillary expander (C-expander) can fail if they contact tooth roots or perforate the maxillary sinus. Cone beam computed tomography images were reviewed retrospectively to evaluate the geometric factors of miniscrew placement in the palate that contribute to root proximity (RP) and sinus perforation (SP), and to investigate the differences of miniscrew placement depth (PD) and placement angle (PA) among the groups in each variable from 340 anchoring miniscrews on 70 patients whose C-expanders showed sufficient stability after palatal expansion for orthodontic treatment. Two types of miniscrews were used: a self-tapping miniscrew with 1.8 mm-in-diameter, and a self-drilling miniscrew with 1.6 mm-in-diameter. While the self-tapping larger diameter miniscrew influenced root proximity significantly, the screw location and PD affected the rate of sinus perforation. PA was significantly different between the right and left sides of the palate. The results of this study confirmed that root proximity and sinus perforation of anchoring miniscrews in a tissue bone borne palatal expander occurred due to certain risk factors, even when the palates were expanded successfully. Knowledge of these factors can help the clinician place miniscrews with less risk of root proximity or sinus perforation.

Biomechanical evaluation of maxillary protraction with an orthodontic anchor screw: a three-dimensional finite element analysis

ABSTRACT Purpose The purpose of this study was to biomechanically evaluate maxillary protraction using an orthodontic anchor screw. We conducted three-dimensional finite element analysis to determine the initial displacement and stress distribution during maxillary protraction by comparing a conventional method involving fixation on teeth with maxillary protraction using an orthodontic anchor screw. Materials and methods We used X-ray computed tomography data obtained from Hellman Dental Age IIIA dry human skulls to create a skeletal anchorage model and a dental anchorage model as finite element models. In each model, a load of 6 N was applied in the anteroinferior direction at 0°, 10°, 20°, 30°, and 40° to the occlusal plane by means of a traction hook and the initial displacement and stress distribution were analysed. Results For the anterior nasal spine (ANS) sagittal displacement was greater in the skeletal anchorage model than in the dental anchorage model. In the central incisors and first molars, greater sagittal displacement was observed in the dental anchorage model compared with the skeletal anchorage model. In both models, vertical displacement was 20°, indicating maximum suppression of rotation in the maxilla. The zygomaticomaxillary and zygomaticofrontal sutures demonstrated high stress at 0° and 10° in the dental anchorage model, and at 20°, 30°, and 40° in the skeletal anchorage model. Conclusions These results indicate that tooth and bone–borne maxillary protraction using an orthodontic anchor screw inserted in the palatal region may be of value for the early mixed dentition period in patients with maxillary deficiency.

Three-dimensional assessment of the spheno-occipital synchondrosis and clivus after tooth-borne and bone-borne rapid maxillary expansion.

To assess changes in spheno-occipital synchondrosis after rapid maxillary expansion (RME) performed with conventional tooth-borne (TB) and bone-borne (BB) appliances. This study included 40 subjects with transverse maxillary deficiency who received TB RME or BB RME. Cone-beam computed tomography images (CBCT) were taken before treatment (T0), and after a 6-month retention period (T1). Three-dimensional surface models of the spheno-occipital synchondrosis and basilar part of the occipital bone were generated. The CBCTs taken at T0 and T1 were registered at the anterior cranial fossa via voxel-based superimposition. Quantitative evaluation of Basion displacement was performed with linear measurements and Euclidean distances. The volume of the synchndrosis was also calculated for each time point as well as the Nasion-Sella-Basion angle (N-S-Ba°). All data were statistically analyzed to perform inter-timing and intergroup comparisons. In both groups, there was a small increment of the volume of the synchondrosis and of N-S-Ba° (P < .05). Basion showed a posterosuperior pattern of displacement. However, no significant differences (P > .05) were found between the two groups. Although TB and BB RME seemed to have some effects on the spheno-occipital synchondrosis, differences were very small and clinically negligible.

Does Mini Screw Assisted Rapid Palatal Expansion (MARPE) have an influence on airway and breathing in middle-aged children and adolescents? A systematic review

This systematic review assessed the effects of tooth-borne (TB), tooth-bone-borne (TBB) and bone-borne (BB) micro-implant assisted rapid maxillary expansion (RPE) on airway dimensions and function in young children and adolescents (10- to 17-years-old). Unrestricted search in 5 electronic databases until June 6th, 2020 was undertaken. This was supplemented with search in 6 additional resources for published, unpublished and ongoing trials up. Randomized (RCT) and non-randomized (Non-RCT) prospective studies that assessed the influence of the mini-screw-assisted rapid palatal expansion (MARPE) approach on airway and breathing in young children and adolescents were included. Two reviewers performed the study selection and data extraction blindly and in duplicate by two authors while disagreements. A random-effects model with a 95% confidence interval (CI), I2 and Chi2 tests were done. ROBINS-I, Cochrane Risk of Bias and GRADE tools were used. Reporting of this review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Overall, 518 articles were retrieved; only 3 studies (2 RCT and one non-RCT) met the inclusion criteria. Both TB RPE and BB RPE improved on a short-term basis the dimensions of the airway, though the difference was not significant (P>0.05). TBB RPE significantly improved nasal airflow [(Mean difference (MD) 52.7 cm3/s, 95% confidence interval (95% CI) 9.0-96.4), P=0.020)], reduced nasal resistance (MD -0.20Pa/cm3, 95% (-0.38)-(-0.02), P=0.028), and changed respiratory muscle strength variables (P>0.05). No correlation was found between the anatomical dimensions of the airway and the functional airway parameters (P>0.05). The short-term airway volumetric changes secondary to MARPE were not significant. The influence of MARPE appliances on breathing is still not clear. Registration PROSPERO database (CRD42020183340).

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)?

Evaluation of the changes of orbital cavity volume and shape after tooth-borne and bone-borne rapid maxillary expansion (RME)

ObjectiveTo assess and compare volumetric and shape changes of the orbital cavity in patients treated with tooth-borne (TB) and bone-borne (BB) rapid maxillary expansion (RME).Study designForty adolescents with bilateral maxillary cross-bite received tooth-borne (TB group = 20; mean age 14.27 ± 1.36 years) or bone-borne (BB group = 20; mean age of 14.62 ± 1.45 years) maxillary expander. Cone-beam computed tomography (CBCT) were taken before treatment (T1) and 6-month after the expander activation (T2). Volumetric and shape changes of orbital cavities were detected by referring to a specific 3D digital technology involving deviation analysis of T1/T2 CBCT-derived models of pulp chamber. Student’s t tests were used to 1) compare T1 and T2 volumes of orbital cavities in TB and BB groups, 2) compare volumetric changes and the percentage of matching of 3D orbital models (T1-T2) between the two groups.ResultsBoth TB and BB groups showed a slight increase of the orbital volume (0.64 cm3 and 0.77 cm3) (p < 0.0001). This increment were significant between the two groups (p < 0.05) while no differences were found in the percentage of matching of T1/T2 orbital 3D models (p > 0.05). The areas of greater changes were detected in the proximity of the frontozygomatic and frontomaxillary sutures.ConclusionTB-RME and BB-RME would not seem to considerably affect the anatomy or the volume of the orbital cavity in adolescents.

Transverse dentoalveolar response of mandibular arch after rapid maxillary expansion (RME) with tooth-borne and bone-borne appliances.

To assess and compare spontaneous expansion of mandibular posterior teeth between tooth-borne (TB) and bone-borne (BB) rapid maxillary expansion (RME). This study included 36 adolescents with bilateral maxillary crossbite receiving tooth-borne (average age: 14.4 ± 1.3 years) or bone-borne (average age: 14.7 ± 1.4 years) maxillary expansion. Cone beam computed tomography was acquired before expansion (T1) and after 6 months' retention (T2). Specific linear and angular measurements were performed in the coronal view to assess buccal inclinations and widths of mandibular posterior units. All data were statistically analyzed. In both groups there was a significant increase in buccal-lingual inclination of mandibular posterior teeth ranging from 1.67° to 2.30° in the TB group and from 1.46° to 2.11° in BB group. Mandibular posterior widths showed an increase ranging from 0.80 mm to 1.33 mm in TB group and from 0.64 mm to 0.96 mm in the BB group. No differences between groups were found for linear or angular measurements. A clinically significant gain of space in the mandibular arch should not be expected after RME.