Changes in the midpalatal and pterygopalatine sutures induced by micro-implant-supported skeletal expander, analyzed with a novel 3D method based on CBCT imaging.

BackgroundMini-implant-assisted rapid palatal expansion (MARPE) appliances have been developed with the aim to enhance the orthopedic effect induced by rapid maxillary expansion (RME). Maxillary Skeletal Expander (MSE) is a particular type of MARPE appliance characterized by the presence of four mini-implants positioned in the posterior part of the palate with bi-cortical engagement. The aim of the present study is to evaluate the MSE effects on the midpalatal and pterygopalatine sutures in late adolescents, using high-resolution CBCT. Specific aims are to define the magnitude and sagittal parallelism of midpalatal suture opening, to measure the extent of transverse asymmetry of split, and to illustrate the possibility of splitting the pterygopalatine suture.MethodsFifteen subjects (mean age of 17.2 years; range, 13.9-26.2 years) were treated with MSE. Pre- and post-treatment CBCT exams were taken and superimposed. A novel methodology based on three new reference planes was utilized to analyze the sutural changes. Parameters were compared from pre- to post-treatment and between genders non-parametrically using the Wilcoxon sign rank test. For the frequency of openings in the lower part of the pterygopalatine suture, the Fisher's exact test was used.ResultsRegarding the magnitude of midpalatal suture opening, the split at anterior nasal spine (ANS) and at posterior nasal spine (PNS) was 4.8 and 4.3 mm, respectively. The amount of split at PNS was 90% of that at ANS, showing that the opening of the midpalatal suture was almost perfectly parallel antero-posteriorly. On average, one half of the anterior nasal spine (ANS) moved more than the contralateral one by 1.1 mm. Openings between the lateral and medial plates of the pterygoid process were detectable in 53% of the sutures (P < 0.05). No significant differences were found in the magnitude and frequency of suture opening between males and females. Correlation between age and suture opening was negligible (R 2 range, 0.3-4.2%).ConclusionsMidpalatal suture was successfully split by MSE in late adolescents, and the opening was almost perfectly parallel in a sagittal direction. Regarding the extent of transverse asymmetry of the split, on average one half of ANS moved more than the contralateral one by 1.1 mm. Pterygopalatine suture was split in its lower region by MSE, as the pyramidal process was pulled out from the pterygoid process. Patient gender and age had a negligible influence on suture opening for the age group considered in the study

Morphometric Analysis of Maxillary Skeletal Expansion Effects on the Nasal Cavity

Introduction: The shape, size and volume of the bony nasal cavity is highly influenced by the width of the nasal floor, which is formed by the palatine bone and the palatal processes of the maxilla and can be orthodontically manipulated with the MSE (Maxillary Skeletal Expansion) technique. Current evaluation of changes in this area before and after expansion relay on cross-sectional areas and airflow measurements. However, these techniques are not able to truly point out the extend of bone changes and volume changes of this important structure. Materials and Method: This retrospective study had a sample of 22 patients distributed in two groups. Group 1 was treated with Hyrax and consisted of 6 growing patients (3 females and 3 males, mean age 12y2mo), group 2 was treated with MSE and consisted of 16 non-growing patients (10 females and 6 males, mean age 20y7mo) who met inclusion criteria. Analysis of CBCT scans before and after expansion treatment was conducted in OnDemand3D software, with automated superimposition on the cranial base. Three reference planes were established, based on reliably identifiable anatomical landmarks, anterior nasal spine (ANS), posterior nasal spine (PNS) and nasion (N). The distance between ANS and PNS in the AP plane was divided into 4 sections, and the distance between ANS and N was divided into 5 sections, excluding the most superior one. Transverse linear measurements at the resulting cross-points between the vertical and horizontal sections resulted in a total of 32 measurement points along the lateral walls of the nasal cavity.Results: The MSE group showed overall statistically significant larger movements of the lateral walls of the nasal cavity (p < 0.05). The bony structures followed the overall expansion pattern of the maxilla, though bending at the orbital rims and areas of higher bone density occured. Conclusion: MSE produces not only larger maxillary skeletal transverse movements, but also shows more expansion effects on the lateral walls of the nasal cavity compared to tooth-borne expansion

Morphometric Analysis of Maxillary Skeletal Expansion Effects on the Nasal Cavity

Introduction: The shape, size and volume of the bony nasal cavity is highly influenced by the width of the nasal floor, which is formed by the palatine bone and the palatal processes of the maxilla and can be orthodontically manipulated with the MSE (Maxillary Skeletal Expansion) technique. Current evaluation of changes in this area before and after expansion relay on cross-sectional areas and airflow measurements. However, these techniques are not able to truly point out the extend of bone changes and volume changes of this important structure. Materials and Method: This retrospective study had a sample of 22 patients distributed in two groups. Group 1 was treated with Hyrax and consisted of 6 growing patients (3 females and 3 males, mean age 12y2mo), group 2 was treated with MSE and consisted of 16 non-growing patients (10 females and 6 males, mean age 20y7mo) who met inclusion criteria. Analysis of CBCT scans before and after expansion treatment was conducted in OnDemand3D software, with automated superimposition on the cranial base. Three reference planes were established, based on reliably identifiable anatomical landmarks, anterior nasal spine (ANS), posterior nasal spine (PNS) and nasion (N). The distance between ANS and PNS in the AP plane was divided into 4 sections, and the distance between ANS and N was divided into 5 sections, excluding the most superior one. Transverse linear measurements at the resulting cross-points between the vertical and horizontal sections resulted in a total of 32 measurement points along the lateral walls of the nasal cavity.Results: The MSE group showed overall statistically significant larger movements of the lateral walls of the nasal cavity (p < 0.05). The bony structures followed the overall expansion pattern of the maxilla, though bending at the orbital rims and areas of higher bone density occured. Conclusion: MSE produces not only larger maxillary skeletal transverse movements, but also shows more expansion effects on the lateral walls of the nasal cavity compared to tooth-borne expansion

Zygomaticomaxillary modifications in the horizontal plane induced by micro-implant-supported skeletal expander, analyzed with CBCT images

BackgroundMiniscrew-assisted rapid palatal expansion (MARPE) has been adopted in recent years to expand the maxilla in late adolescence and adult patients. Maxillary Skeletal Expander (MSE) is a device that exploits the principles of skeletal anchorage to transmit the expansion force directly to the maxillary bony structures and is characterized by the miniscrews' engagement of the palatal and nasal cortical bone layers. In the literature, it has been reported that the zygomatic buttress is a major constraint that hampers the lateral movement of maxilla, since maxilla is located medially to the zygomatic arches. The objective of the present study is to analyze the changes in the zygomatic bone, maxillary bone, and zygomatic arches and to localize the center of rotation for the zygomaticomaxillary complex in the horizontal plane after treatment with MSE, using high-resolution cone-beam computed tomography (CBCT) images.MethodsFifteen subjects with a mean age of 17.2 (± 4.2) years were treated with MSE. CBCT records were taken before and after miniscrew-assisted maxillary expansion; three linear and four angular parameters were identified in the axial zygomatic section (AZS) and were compared from pre-treatment to post-treatment using the Wilcoxon signed rank test.ResultsAnterior inter-maxillary distance increased by 2.8 mm, posterior inter-zygomatic distance by 2.4 mm, angle of the zygomatic process of the temporal bone by 1.7° and 2.1° (right and left side) (P < 0.01). Changes in posterior inter-temporal distance and zygomaticotemporal angle were negligible (P > 0.05).ConclusionsIn the horizontal plane, the maxillary and zygomatic bones and the whole zygomatic arch were significantly displaced in a lateral direction after treatment with MSE. The center of rotation for the zygomaticomaxillary complex was located near the proximal portion of the zygomatic process of the temporal bone, more posteriorly and more laterally than what has been reported in the literature for tooth-borne expanders. Bone bending takes place in the zygomatic process of the temporal bone during miniscrew-supported maxillary expansion

Zygomaticomaxillary modifications in the horizontal plane induced by micro-implant-supported skeletal expander, analyzed with CBCT images

Abstract Background Miniscrew-assisted rapid palatal expansion (MARPE) has been adopted in recent years to expand the maxilla in late adolescence and adult patients. Maxillary Skeletal Expander (MSE) is a device that exploits the principles of skeletal anchorage to transmit the expansion force directly to the maxillary bony structures and is characterized by the miniscrews’ engagement of the palatal and nasal cortical bone layers. In the literature, it has been reported that the zygomatic buttress is a major constraint that hampers the lateral movement of maxilla, since maxilla is located medially to the zygomatic arches. The objective of the present study is to analyze the changes in the zygomatic bone, maxillary bone, and zygomatic arches and to localize the center of rotation for the zygomaticomaxillary complex in the horizontal plane after treatment with MSE, using high-resolution cone-beam computed tomography (CBCT) images. Methods Fifteen subjects with a mean age of 17.2 (± 4.2) years were treated with MSE. CBCT records were taken before and after miniscrew-assisted maxillary expansion; three linear and four angular parameters were identified in the axial zygomatic section (AZS) and were compared from pre-treatment to post-treatment using the Wilcoxon signed rank test. Results Anterior inter-maxillary distance increased by 2.8 mm, posterior inter-zygomatic distance by 2.4 mm, angle of the zygomatic process of the temporal bone by 1.7° and 2.1° (right and left side) (P  0.05). Conclusions In the horizontal plane, the maxillary and zygomatic bones and the whole zygomatic arch were significantly displaced in a lateral direction after treatment with MSE. The center of rotation for the zygomaticomaxillary complex was located near the proximal portion of the zygomatic process of the temporal bone, more posteriorly and more laterally than what has been reported in the literature for tooth-borne expanders. Bone bending takes place in the zygomatic process of the temporal bone during miniscrew-supported maxillary expansion