Three-dimensional Analysis of Factors Related to the Effective Alveolar Molding in Presurgical Infant Orthopedics: Findings From a Pilot Study.

OBJECTIVE: Presurgical infant orthopedics (PIO) reduces the severity of the original cleft and burden on patients and their parents, provides better esthetics and function, and enables surgeons to achieve better surgical repair. To reduce the alveolar cleft width and to predict treatment difficulty using PIO, various measures were examined in pretreatment cast models. DESIGN: Retrospective case-control pilot study. PATIENTS: The patients were 22 infants with non-syndromic unilateral cleft lip and palate (UCLP), and cast models of these infants were used. METHODS: After PIO using passive plates, infants with UCLP were divided into two groups: contact group (12 cases with close proximity of the greater and lesser segments) and non-contact group (10 cases without proximity of segments). The two groups were compared, and variables related to the proximity between alveolar clefts were examined. RESULTS: There was no significant difference in age at PIO initiation between the two groups. However, the treatment duration was significantly longer in the non-contact group than in the contact group. Among the 13 variables, the initial lateral deviation of the nasal septum was significantly larger in the contact group than in the non-contact group. A significant positive correlation was observed between the initial lateral deviation of the nasal septum and reduction of the alveolar cleft width by PIO. CONCLUSION: Initial lateral deviation of the nasal septum is a predictive factor for the proximity between alveolar segments in infants with UCLP at the PIO.

Effects of jaw movement in bimaxillary orthognathic surgery on the upper airway: Computational fluid dynamics analysis.

Maxillomandibular repositioning in orthognathic surgeries has both morphologic and functional effects. These surgeries are thought to change the pharyngeal space and cause obstructive sleep apnoea syndrome, however. The primary purpose of this study is to evaluate the effects of jaw movement in bimaxillary orthognathic surgery on airway function and to identify the morphometric factors that can predict postoperative airway function. The subjects were 11 males and 12 females who had undergone orthognathic surgeries of the maxilla and mandible. The results of cephalometric analysis, cross-sectional area of the pharynx (CSA), pharyngeal volume and computational fluid dynamics (CFD) were compared. The CSA of the nasal (CSA1), total volume and total nasal volume decreased after surgery with statistical significance. Velocity at the oropharyngeal space (V2) increased after surgery with statistical significance. V2, CSA of the oropharyngeal space (CSA2) and PV were correlated with the horizontal posterior movement of point B, point Menton and overjet. V2 and CSA2 were correlated with SNB before and after surgery in all 46 analyses. Changes in pharyngeal airflow were more affected by pressure drop in the pharyngeal space (ΔPp) than by pressure drop in the nasal space (ΔPn). The relationship between the actual amount of change in the cephalometric reference point and the airway function is evident. CFD may thus be very useful as morphological analysis in preoperative treatment decision making.

Orthodontic treatment of a skeletal Class III malocclusion with severe root resorption of the maxillary anterior teeth. Autotransplantation using a 3-dimensional printed replica of the donor tooth.

This case report describes the successful orthodontic treatment of a 12-year-old girl with skeletal Class III malocclusion and severe root resorption of the maxillary anterior teeth. Ectopic eruption and mesial inclination of the bilateral maxillary canines caused severe root resorption of the right central and lateral incisors and the left lateral incisor. These 3 teeth were extracted, and traction was applied to the maxillary right and left canines toward the extracted right central incisor and left lateral incisor, respectively. In the mandibular arch, the bilateral first premolars were extracted, and the crowding was corrected. The extracted mandibular right first premolar was transplanted after extraction of the maxillary right lateral incisor. To prepare for the tooth transplantation, a cone-beam computed tomography image was used to fabricate a 3-dimensional printed replica of the donor tooth. The crown shape of the maxillary anterior teeth was corrected, and the patient achieved functional occlusion with pleasing esthetics. Root resorption was negligible in the transplanted tooth. This study demonstrates the satisfactory treatment outcome and an effective 3-dimensional simulation for tooth transplantation.

Different Therapeutic Effects of CO2 and Diode Laser Irradiation on Tooth Movement-Related Pain.

Although orthodontic treatment is common, orthodontic force often induced pain. Low-level laser therapy (LLLT) has been investigated to improve therapeutic comfort. In dentistry, LLLT is mainly applied using two types of lasers, CO2 and diode lasers, whose biological actions are thought to be associated with wavelength (CO2: 10,600 nm; diode: 808 nm). The analgesic effect of LLLT on orthodontic treatment-related pain is widely reported but inconsistent. This study aimed to (1) determine whether irradiation with a CO2 or diode laser attenuates orthodontic treatment-related pain using the jaw-opening reflex model, (2) elucidate the optimal irradiation protocol for both lasers to obtain the maximal analgesic effect, (3) evaluate the effects of laser irradiation on other biological features [e.g., tooth movement, glial fibrillary acidic protein (GFAP) expression, and temperature alterations] and (4) investigate the mechanism underlying the analgesic effect of laser irradiation. In this animal model, orthodontic treatment-induced pain manifested as a significantly reduced the threshold for inducing the jaw-opening reflex on the orthodontically treated side compared with the contralateral side. GFAP expression in the bilateral trigeminal ganglia (TGs) was significantly increased by the application of orthodontic force. CO2 laser irradiation of the orthodontically treated region significantly increased the threshold for inducing the jaw-opening reflex and the peripheral temperature. Similar reductions in jaw-opening reflex excitability were induced by surface anesthesia and thermal stimulation but not, the diode laser. Neither CO2 nor diode laser irradiation altered GFAP expression in the TGs. Infiltration anesthesia also significantly increased the threshold for inducing the jaw-opening reflex on each anesthetized side. Irradiation (30 s) by either laser immediately after orthodontic force application (preirradiation) significantly decreased jaw-opening reflex excitability and GFAP expression in the bilateral TGs the next day. However, thermal stimulation immediately after orthodontic force application failed to alter jaw-opening reflex excitability the next day. Laser irradiation did not alter tooth movement; however, an optimized irradiation protocol for aiding tooth movement is suggested. In conclusion, both CO2 and diode lasers are able to prevent orthodontic treatment-related pain. Furthermore, the involvement of temperature alterations and surface anesthesia in the analgesic effect induced by CO2 laser irradiation is suggested.

Orthodontic treatment-induced temporal alteration of jaw-opening reflex excitability.

The impairment of orofacial motor function during orthodontic treatment needs to be addressed, because most orthodontic patients experience pain and motor excitability would be affected by pain. In the present study, the temporal alteration of the jaw-opening reflex excitability was investigated to determine if orthodontic treatment affects orofacial motor function. The excitability of jaw-opening reflex evoked by electrical stimulation on the gingiva and recorded bilaterally in the anterior digastric muscles was evaluated at 1 (D1), 3 (D3), and 7 days (D7) after orthodontic force application to the teeth of right side; morphological features (e.g., osteoclast genesis and tooth movement) were also evaluated. To clarify the underlying mechanism of orthodontic treatment-induced alteration of orofacial motor excitability, analgesics were administrated for 1 day. At D1 and D3, orthodontic treatment significantly decreased the threshold for inducing the jaw-opening reflex but significantly increased the threshold at D7. Other parameters of the jaw-opening reflex were also evaluated (e.g., latency, duration and area under the curve of anterior digastric muscles activity), and only the latency of the D1 group was significantly different from that of the other groups. Temporal alteration of the jaw-opening reflex excitability was significantly correlated with changes in morphological features. Aspirin (300 mg·kg-1·day-1) significantly increased the threshold for inducing the jaw-opening reflex, whereas a lower dose (75-150 mg·kg-1·day-1) of aspirin or acetaminophen (300 mg·kg-1·day-1) failed to alter the jaw-opening reflex excitability. These results suggest that an increase of the jaw-opening reflex excitability can be induced acutely by orthodontic treatment, possibly through the cyclooxygenase activation.NEW & NOTEWORTHY It is well known that motor function is affected by pain, but the effect of orthodontic treatment-related pain on the trigeminal motor excitability has not been fully understood. We found that, during orthodontic treatment, trigeminal motor excitability is acutely increased and then decreased in a week. Because alteration of trigeminal motor function can be evaluated quantitatively by jaw-opening reflex excitability, the present animal model may be useful to search for alternative approaches to attenuate orthodontic pain.

Localization of heat shock protein 27 (hsp27) in the rat gingiva and its changes with tooth eruption.

Heat shock protein 27 kDa (Hsp27) functions as a molecular chaperon to prevent apoptosis as well as to contribute to the regulation of cell proliferation and differentiation during development. In the present study, the localization of Hsp27 in the oral epithelium of rats and its expression change during formation of the gingiva with the tooth eruption were examined immunohistochemically to elucidate the roles of Hsp27 in the oral mucosa.In adult rats, Hsp27-immunoreactivity was localized in the prickle and granular layers but absent in the basal and horny layers of the oral epithelium. On the other hand, in the outer and sulcular epithelia of the free gingival, Hsp27-immunoreactivity was detected in the whole layers, while it was not found in the proliferation zone of the junctional epithelium immunoreactive for Ki67. In immature rats on 10th postnatal day, Hsp27-immunoreactivity was intense in the prickle and granular layers of the oral epithelium, but was not detected in its basal layer. In rats at the eruptive phase on 15th postnatal day, Hsp27-immunoreactivity was detected in sites of the basal layer adjacent to where the dental cusps penetrated through the oral epithelium. Although the immunoreactivity for Ki67 was found in the basal layer of the oral epithelium, it was not localized in the Hsp27-immunopositive sites of tooth-penetration in the basal layer. Just after the tooth-eruption on 20th postnatal day, Hsp27-immunoreactivity was not found in the stratified squamous epithelium at the dentogingival junction, whereas it was intense in a single layer of cuboidal epithelial cells attached to the tooth neck. Ki67-positive cells were scattered in the stratified squamous epithelium at the dentogingival junction, whereas no positive cells were found in the portion of a single layer of cuboidal epithelial cells.These findings suggest that the outer and sulcular epithelia of the free gingiva have a relatively slower rate of proliferation than other gingival and oral epithelia, and that Hsp27 might inhibit the proliferation of the basal cells. Such specific phenomenon in the free gingiva occurred immediately after the dental cusps were exposed to the oral cavity.

Effect of simulated orthodontic forces on fluoride-induced cytotoxicity in MC3T3-E1 osteoblast-like cells.

The effects of simulated orthodontic forces such as centrifugal force or water pressure on sodium fluoride (NaF)-induced cytotoxicity against mouse osteoblast-like cells MC3T3-E1 were investigated. Loading with centrifugal force (44.5 g/cm2) or water pressure (5 g/cm2) slightly reduced the cell proliferation and additively enhanced the cytotoxic activity of millimolar concentrations of NaF. NaF induced the appearance of phosphatidylserine at outer cell membrane (detected by Annexin staining) but failed to induce caspase-3 activation even under the water pressure. On the other hand, NaF induced autophagic phenotype characterized by the formation of acidic organelles (detected by acridine orange staining). NaF did not increase, but rather dose-dependently reduced the alkaline phosphatase activity, with or without the loading of water pressure. The present study demonstrates that centrifugal force and water pressure partially enhanced the caspase-independent cytotoxicity of NaF against osteoblasts. These simulated orthodontic forces may be a new factor that affects the physiological activity of NaF.