Relapse tendency in maxillary arch width in unilateral cleft lip and palate patients with different maxillary arch forms.

OBJECTIVE: The aim of this study was to investigate the relapse tendency in the maxillary dental arch widths in unilateral cleft lip and palate patients with different types of maxillary arch form. SUBJECTS: Thirty-two unilateral cleft lip and palate patients treated by one-stage surgical palatal closure were included. The subjects were divided into three groups according to the types of the maxillary arch forms: group A, symmetrical arch form; group B, collapse of minor segment; group C, collapse of both segments. METHODS: Using dental casts obtained at three different times, relapse in the intercanine, interpremolar, and intermolar widths in each group was assessed and differences between groups were investigated. RESULTS: Patients in group A showed stable results in all measurements. Patients in group B showed posttreatment relapse in the intercanine width only, whereas patients in group C demonstrated significant posttreatment relapses in the interpremolar and intermolar widths. Comparison between groups showed more significant relapse in the interpremolar and intermolar widths of group C than in those of group B. CONCLUSION: The types of the maxillary arch forms in unilateral cleft lip and palate patients might play a stronger role in the stability of the maxillary dental arch widths after orthodontic treatment in patients with collapse of both segments and a severe degree of maxillary narrowness.

Anchorage effect of osseointegrated vs nonosseointegrated palatal implants.

Palatal implants can be used with a transpalatal arch (TPA) connected with the second premolar to provide anchorage. The purpose of this study was to compare the anchorage effects of an osseointegrated palatal implant (OPI) with a nonosseointegrated palatal implant (NOPI), using finite element analysis. One model, which was composed of two maxillary premolars, periodontal ligament (PDL), alveolar bone, a palatal implant, palatal bone, a bracket, band, and TPA, was created on the basis of the clinical situation. The palatal implant was treated as either NOPI or OPI. The force on the premolars was investigated under three conditions: a distomesial horizontal force, a buccolingual horizontal force, and a vertical intrusive force. The PDL stress was calculated and compared with a model without an implant. The result showed that OPI could reduce PDL stress significantly. (The average stress was reduced by 14.44% for the distomesial horizontal force, 60.28% for the buccolingual horizontal force, and 17.31% for the vertical intrusive force.) The NOPI showed almost the same anchorage effect as OPI. The stress on the NOPI surface was higher than that on the OPI surface, but the stress was not high enough to result in failure of the implant. These results suggested that waiting for osseointegration might be unnecessary for an orthodontic implant.

Analysis of head and mandibular tapping movements in patients with mandibular protrusion.

The present study was conducted to investigate whether there was a functional coupling between the head and mandibular movements in ten patients with mandibular protrusion (MP) and ten control subjects with normal occlusion (Normal), using a six degrees-of-freedom measuring device. Single-peak waveforms were predominantly seen in both MP (98.2%) and Normal (99.3%). However, vertical displacements of the upper and lower incisor points (VD(UIP) and VD(LIP)) were all significantly larger in MP than those in Normal. The ratio VD(UIP)/VD(LIP) also increased more sharply with an increase in VD(LIP) in MP, compared to that in Normal. Mandibular rotation in MP was also significantly larger than that in Normal. The results showed that, in MP, the head moves more vertically in rhythmical coordination with mandibular movement during tapping. Finally, it may be that this larger vertical head movement is related to the greater condylar rotation in MP subjects.

Craniofacial morphology and inclination of the posterior slope of the articular eminence in female patients with and without condylar bone change.

This study investigated the association of craniofacial and glenoid fossa shapes and temporomandibular joint (TMJ) pathology in 39 orthodontic patients with signs and symptoms of TMJ disorders, using helical CT scans. Cephalometric measurements showed that 21 subjects with bilateral condylar bone change (BBC) had significantly smaller SNB angles, ramus heights and S-Ar/N-Ba ratios, as well as larger mandibular plane angles and lower anterior facial height than the 18 subjects with no condylar bone change (NBC). The average posterior slope of the left and right articular eminence in their central and lateral sections was significantly steeper in NBC than in BBC. Condylar bone change might, therefore, not only be related to the morphology of the mandible, but also of the glenoid fossa and cranial base. This appears to reflect adaptive changes in the condyle, articular eminence and cranial base in response to changes in loading.

Condylar bone change and sagittal incisal and condylar paths during mandibular protrusive excursion.

This study showed significant differences in sagittal condylar and incisal path angles during mandibular protrusive excursion, as well as flattening of the condylar path related to the existence and type of condylar bone change. Twenty-eight (28) patients with signs and symptoms of TMJ disorders were studied, using a six-degrees-of-freedom measuring device and helical CT. Sagittal incisal and condylar path angles at two mm and three mm condylar path lengths (CPL) were significantly shorter in the bilateral condylar bone change (BBC), compared to the no bone change (NBC) group. Also, NBC incremental sagittal condylar path angles from three to five mm CPL and NBC condylar path curvature at five mm CPL were both significantly larger than in BBC. Comparing types of bone change, incremental sagittal condylar path angles from three to five mm CPL was significantly less in osteophyte than in NBC or erosion groups. Condylar path curvature at five mm CPL was also significantly less in osteophyte than in NBC.

Predicting the pharyngeal airway space after mandibular setback surgery.

PURPOSE: The purpose of this study is to propose a mathematical model to predict the change in pharyngeal airway space (PAS) associated with mandibular setback surgery. PATIENTS AND METHODS: Twenty-three female adults, who were diagnosed as having skeletal Class III deformity, underwent mandibular setback surgery by bilateral sagittal split ramus osteotomy (BSSO) and orthodontic multibracket treatment. The subjects were assessed within 6 months before operation (T1) and 1 to 1.5 years after mandibular setback surgery (T2). The PAS change in the level of the base of the tongue was predicted. RESULTS: The equation is: PAS narrowing = 0.386 - 0.541 ANB (T1 - T2) + 0.253 Co-Gn (T1 - T2) - 0.098 SN-GoGn (T1 - T2), where ANB is the angle formed by the planes nasion-point A and nasion-point B, Co is condylion, Go is gonion, and Gn is gnathion. The PAS change can be predicted by the mandibular changes after setback surgery 66.2% with the regression equation using the change of the ANB angle, the total mandibular length (Co-Gn) and the mandibular plane (SN-GoGn), where SN is sella-nasion. CONCLUSIONS: The equation can be used to predict the change of pharyngeal airway space after mandibular setback surgery. In patients who have other risk factors, such as obesity, short neck, macroglossia, large uvula, and excessive soft tissue around the nasopharyngeal region, a mandibular setback surgery could possibly predispose to the development of sleep apnea syndrome.

Anchorage effects of a palatal osseointegrated implant with different fixation: a finite element study.

The purpose of this study was to compare the anchorage effect of the osseointegrated implant with different fixation types using finite element analysis. Three fixation types were investigated. fixation type 1: implant neck in the oral-palatal cortical bone and implant tip in the cancellous bone; fixation type 2: implant neck in the oral-palatal cortical bone and implant tip in the nasal-palatal cortical bone; fixation type 3: implant neck in the oral-palatal cortical bone and implant tip projecting into the nasal cavity. Three finite element models were constructed. Each consisted of two maxillary second premolars, their associated periodontal ligament (PDL), alveolar bones, palatal bone, palatal implant, and a transpalatal arch. Another model without an implant was used to compare with the previous models. The horizontal force (mesial five N, palatal one N) was loaded at the buccal bracket of each second premolar. The stress was calculated in the PDL and implant surrounding bone. The result showed that the palatal implant could significantly reduce von Mises stress (maximum von Mises stress was reduced 30%) and evenly distribute stress in the PDL. The stress magnitude and distribution in the PDL was almost the same in the three implant models. These results suggest that different implant fixation types have almost the same anchorage effects.

Double contours and craniofacial morphology.

This study was done to try to clarify the relationship between double contours and craniofacial morphology. The study sample included 56 pre-orthodontic patients with signs and symptoms of temporomandibular joint (TMJ) disorders. A comparison of craniofacial structures was done on 32 subjects with bilateral condylar bone change (BBC group: 28 female and 4 male) and 24 subjects with no condylar bone change (NBC group: 21 female and 3 male). The BBC showed significantly greater antegonial and ramus notch depths, as well as significantly more retruded mandibles, shorter ramus heights, and larger mandibular plane angles than the NBC. BBC subjects with bilateral double contours showed significantly more retruded mandibles, larger antegonial notch depth, and shorter lengths from the Sella to the Articulare than BBC subjects with no double contours. The study showed that important relationships exist between the presence of double contours and mandibular morphology and TMJ position.

A special method of predicting mandibular growth potential for Class III malocclusion.

The purpose of this study was to establish an equation to predict the mandible growth potential (GP) for Class III malocclusion on the basis of the analysis of the cervical vertebrae in a single cephalometric radiograph and to compare its predictive accuracy with other methods. Data comprised two groups each with 22 Japanese girls. Group A was examined to construct the prediction equation. Group B served to compare the predictive accuracy with the GP method and the method of Mito et al (MM). The following results were obtained: (1) an equation was determined to obtain mandible GP on the basis of measurements in the third and fourth cervical vertebral bodies and (2) the average errors between the predicted increment and the actual increment for each method were 1.45 mm for the equation, 2.91 mm for the GP method, and 2.48 mm for the MM. These results suggest that using cervical vertebral measurements might allow predicting the mandible GP length for Class III malocclusion.

Nonsurgical treatment of adult open bite using edgewise appliance combined with high-pull headgear and class III elastics.

This case report describes the effect of a combination of high-pull headgear and Class III elastics on the nonsurgical treatment of an adult open bite. The 19-year 1-month-old Japanese female presented with the anterior open bite of 4.0 mm and mild crowding. She had a skeletal Class II but a Class III molar relationship due to a severe proclination of the mandibular dental arch. Unilateral congenital missing premolars caused a discrepancy between the facial and dental midline. After extraction of two premolars and the impacted mandibular third molars, nonsurgical therapy was performed using the standard edgewise appliance combined with a high-pull headgear and Class III elastics. The successful treatment outcome and stability of the final occlusion indicates that a combination of high-pull headgear and Class III elastics is one of the effective devices in the nonsurgical treatment of open bite and, is especially helpful in uprighting the mandibular dental arch.

A new method of predicting mandibular length increment on the basis of cervical vertebrae.

The purpose of this study was to establish an equation to predict incremental mandibular length on the basis of the analysis of the cervical vertebrae in a single cephalometric radiograph and to compare the predictive accuracy with other methods. Data comprised two groups of 23 Japanese girls between CVMS I and CVMS V. Group A was examined to construct the predication equation. Group B served to compare the predictive accuracy with the growth potential method and the growth percentage method. The following results were obtained: (1) an equation was determined to obtain mandibular length increments on the basis of the measurements in the third and fourth cervical vertebral bodies, and (2) the average error between the predicted increment and the actual increment was 1.5 mm for the equation method, 2.4 mm for the growth potential method, and 2.8 mm for the growth percentage method. These results suggest that with the use of cervical vertebral measurements, it may be possible to evaluate the mandibular growth potential.

The relationship between morphological changes of the condyle and condylar position in the glenoid fossa.

AIMS: To investigate whether condylar morphological changes influence the condyle position in the glenoid fossa as well as the amount of condylar movement from the intercuspal position (IP) to the reference position (RP). METHODS: Helical computed tomography was used for precise measurement of the joint spaces at IP and RP in 22 subjects (mean age 22.7 years). Subjects were divided into 2 groups, those without condylar bone changes (n = 11) and those with condylar bone changes (n = 11). The latter group was further subdivided into a flattening subgroup and an osteophyte subgroup, according to the type of condylar bone change. RESULTS: There were no significant differences in the width of the anterosuperior or posterosuperior joint spaces at IP between either the 2 groups or the 2 subgroups. On the other hand, during condylar movement from IP to RP, the condyles moved significantly more superiorly and posterosuperiorly in the bone-change group than in the no-bone-change group. There was also greater absolute horizontal condylar movement between IP and RP in the bone-change group. In addition, within the bone-change group, the type of condylar bone change influenced the amount of condylar movement. Joints with osteophyte formation showed the most superior, posterosuperior, and absolute horizontal movement from IP to RP. CONCLUSION: The findings that condyles of the bone-change group, especially those with osteophyte formation, were located significantly more anteroinferiorly in the glenoid fossa at IP than RP than the condyles of the no-bone-change group suggest that condylar IP-RP positional changes might be related to condylar shape alteration.

The relationship between retruded contact position and intercuspal position in patients with TMJ osteoarthritis.

This study was conducted to investigate the relationship between posterior mandibular excursion movement and temporomandibular joint osteoarthntis (TMJ OA) in 25 orthodontic patients with Angle Class I and Class II, using a six degrees-of-freedom measuring device and helical computed tomography. There were significant differences found in three-dimensional length, antero-posterior, absolute latero-medial and supero-inferior incisal, and condylar intercuspal position (IP)-retruded contact position (RCP) slides between bilateral, unilateral, and no condylar bone change groups. With respect to the types of condylar bone change, there were significant differences found in three-dimensional length, antero-postenor, and absolute latero-medial condylar IP-RCP slides between flattening, erosion and osteophyte groups. These results suggest that large three-dimensional, not only incisal but also condylar, IP-RCP slides might be related to the uni-/bilaterality and kind of TMJ pathosis, which might make such slides useful as clinical indices of TMJ OA.

Involvement of brain-derived neurotrophic factor (BDNF) in the development of periodontal Ruffini endings.

The periodontal Ruffini ending has been reported to show immunoreactivity for tyrosine kinase B (trkB), the high-affinity receptor for brain-derived neurotrophic factor (BDNF), in the periodontal ligament of the rat incisor. Furthermore, adult heterozygous BDNF-mutant mice showed malformation and reduction of the periodontal Ruffini endings. To investigate further roles of BDNF in these structures, the development, distribution, and terminal morphology of Ruffini endings were examined in the incisor periodontal ligament of heterozygous and homozygous BDNF mutant mice, as well as in the wild-type littermate by immunohistochemistry for protein gene product (PGP) 9.5, a general neuronal marker. A similar distribution and terminal formation of PGP 9.5-immunoreactive nerve fibers was recognized in the periodontal ligament of all phenotypes at postnatal week (PW) 1. At this stage, the nerve fibers had a beaded appearance, but did not form the periodontal Ruffini endings. At PW2, the heterozygous and wild-type mice started to show ramified nerve fibers resembling the mature shape of periodontal Ruffini endings. At PW3, the Ruffini endings occurred in the periodontal ligament of the wild-type and heterozygous mice. While the Ruffini endings of the wild-type mice appeared either ruffled or smooth, as reported previously, most of these structures showed a smooth outline in the heterozygous mice. The homozygous mice lacked the typical Ruffini endings at PW3. In the quantitative analysis, homozygous mice had the smallest percentages of PGP 9.5-immunoreactive areas at the same postnatal periods, but there were no significant differences between wild-type and heterozygous mice during PW1-3. These findings suggest a possible involvement of BDNF during the postnatal development and, in particular, the maturation of periodontal Ruffini endings. Furthermore, other neurotrophins may play a role in the development and/or early maturation of the periodontal nerve fibers, as indicated by the presence of nerve fibers in the BDNF-homozygous mice.

Long-term results of the two-stage palatoplasty/Hotz' plate approach for complete bilateral cleft lip, alveolus and palate patients.

PURPOSE: To investigate the effects of the two-stage palatoplasty combined with the Hotz' plate on craniofacial development in patients with bilateral complete clefts. MATERIAL AND METHODS: Lateral and frontal cephalograms of two-stage palatoplasty/Hotz' plate group (n=10), one-stage palatoplasty group (n=11), and a non-cleft group (n=11), were evaluated at 6, 8, 10 and 12 years of age. The unpaired Student's t-test and Scheffe's F test (p<0.05) were applied. RESULTS: At 6 years the posterior upper facial height (PUFH) and PUFH/PFH ratio were greater in the two-stage group. At 10 years the PUFH, maxillary depth, convexity and ANB angle were greater in the same group. At 12 years, maxillary depth and ANB angle were also greater in this group. In the one-stage group, the L1/Mp. angle, PUFH and PUFH/PFH ratio were smaller when compared with the non-cleft group, whereas the palatal plane/SN angle was greater. In both cleft groups, the I.I. angle and tongue-PTM' distance were greater, and the U1/SN angle was smaller when compared with non-clefts. The UC-UC' and the ratios UC/MAX and UC/LC of both cleft groups were also smaller when compared with non-clefts. The ratio UM/MAX of the one-stage group was smaller when compared with the non-cleft group. CONCLUSION: The two-stage palatoplasty in combination with application of the Hotz' plate had good effects on the maxillary growth up to the age of 12 years.

Temporal expression of immunoreactivity for heat shock protein 25 (Hsp25) in the rat periodontal ligament following transection of the inferior alveolar nerve.

The present study examined the immunohistochemical localization of heat shock protein 25 (Hsp25) during the regeneration of nerve fibers and Schwann cells in the periodontal ligament of the rat lower incisor following transection of the inferior alveolar nerve. In the untreated control group, the periodontal ligament of rat incisor did not contain any Hsp25-immunoreaction. On postoperative day 3 (PO 3d), a small number of Schwann cells with slender cytoplasmic processes exhibited Hsp25-immunoreactivity. From PO 5d to PO 21d, Hsp25-positive nerve fibers and Schwann cells drastically increased in number in the alveolar half of the ligament. Although the axons of some regenerating Ruffini-like endings also showed Hsp25-immunoreactions, the migrated Schwann cells were devoid of Hsp25-immunoreaction. Thereafter, Hsp25-positive structures decreased in number gradually to disappear from the periodontal ligament by PO 56d. This temporal expression of Hsp25 in the periodontal ligament well-reflected the regeneration process of the nerve fibers. Hsp25 in the regenerating nerve fibers and denervated Schwann cells most likely serves in modulating actin dynamics and as a cellular inhibitor of apoptosis, respectively.

The involvement of brain-derived neurotrophic factor (BDNF) in the regeneration of periodontal Ruffini endings following transection of the inferior alveolar nerve.

The present study employed immunohistochemistry for protein gene product 9.5 (PGP 9.5) to examine the regeneration process of Ruffini endings, the primary mechanoreceptor in the periodontal ligament, in heterozygous mice with targeted disruption of the brain-derived neurotrophic factor (BDNF) gene and their littermates, following transection of the inferior alveolar nerve. When immunostained for PGP 9.5, periodontal Ruffini endings appeared densely distributed in the periodontal ligament of the heterozygous mice, but the density of the positively stained nerve fibers in the ligament was 20% lower than that in the control littermates. At 3 days after surgery, the PGP 9.5-positive neural elements had disappeared; they began to appear in the periodontal ligament of both animals at 7 days. However, the recovery pattern of the PGP 9.5-positive nerves differed between heterozygous and wild type mice, typical periodontal Ruffini endings morphologically identical to those in the control group appeared in the wild-type mice at 7 days, whereas such Ruffini endings were detectable in the heterozygous mice at 28 days, though much smaller in number. On day 28, when PGP 9.5-positive nerves were largely regenerated in wild type mice, their distribution was much less dense in the ligament of the heterozygous mice than in the non-treated heterozygous mice. The density of PGP 9.5-positive nerve fibers was significantly lower in the heterozygous mice than in wild type mice at any stage examined. These data showing that a reduced expression of BDNF causes delayed regeneration of the periodontal Ruffini endings suggest the involvement of BDNF in the regeneration process of these mechanoreceptors.

The periodontal Ruffini endings in brain derived neurotrophic factor (BDNF) deficient mice.

Innervation and terminal morphology in the lingual periodontal ligament of the incisor were investigated in brain derived neurotrophic factor (BDNF) heterozygous mice and littermate wild-type mice (aged two months) using immunohistochemistry for protein gene product 9.5 (PGP 9.5), a general neuronal marker. In addition, computer-assisted quantitative analysis was performed for a comparison of neuronal density in the periodontal ligament between heterozygous and wild-type mice. In wild-type mice, the periodontal ligament was found to be richly innervated by the mechanoreceptive Ruffini endings and nociceptive free nerve endings in the alveolus-related part of the periodontal ligament. The periodontal Ruffini endings in the wild-type mice incisor ligament were classified into two types: type I with ruffled outlines, and type II with a smooth outline. BDNF heterozygous mice showed malformations of the type I Ruffini endings which included fewer nerve fibers and fewer ramifications than those in wild-type mice as well as smooth outlines of the axon terminals. Quantitative analysis under a confocal microscope showed a roughly 18% reduction in neuronal density in the periodontal ligament of the heterozygous mice. These findings suggest that the development and maturation of the periodontal Ruffini endings require BDNF.

Effects of the inferior alveolar nerve stimulation on tongue muscle activity during mastication in freely behaving rabbits.

Genioglossus (Gg) reflexes elicited by electrical stimulation of the inferior alveolar nerve were examined in naturally chewing rabbits. To eliminate possible contaminations of the digastric (Dig) activity in the Gg responses, the Dig nerve was denervated bilaterally. Masticatory and tongue muscles were well coordinated during chewing after the denervation; i.e., there were no significant differences in the phase durations between before and after denervation. The Gg reflex measured was divided into three categories depending on the chewing phase (i.e., jaw-opening, OP; fast-closing, FC; and slow-closing, SC) in which the stimulus was delivered. The reflex amplitude was phasically modulated for the phases, in that the amplitude in the OP phase was larger than that in any other phase (P<0.05). On the other hand, the amplitude in the FC and SC phases was not significantly different to each other and from the control value obtained when the animal was awake and resting. The pattern of the modulation in the reflex amplitude was different from the previous report as to the Dig reflex in that OP

Relationship between bilateral condylar bone change and mandibular morphology: a study using morphometry.

This study was undertaken to evaluate the relationship between bilateral condylar bone change (BCBC) and mandibular morphology. Thirty Japanese women with BCBC as diagnosed from computed tomographic scans were compared to 2 control groups: 26 Class I and 25 Class II Japanese women. All cephalograms were traced and scanned, and 14 homologous landmarks were digitized. Coordinates were used for cephalometric analysis, Procrustes analysis, Euclidean distance matrix analysis (EDMA), and thin-plate spline (TPS) analysis. Comparison of the cephalometric data for the BCBC and Class I groups revealed significant shrinkage in the condylar process and ramus height, in addition to a shorter body length. The centroid size showed that BCBC mean geometric forms were smaller than those of Class I and Class II. The landmark morphology of the BCBC group differed from both Class I and Class II, as shown by the residuals (P < .001). EDMA showed expansion of infradentale-pogonion (9.9%) and along the anterior slope height of the condyle (28.6%), while the posterior slope height decreased (21.6%). The vertical ramus height (gonioncondylion) also decreased by 11.8% in comparison to Class I. Compared to Class II, BCBC ramus height was shorter by 8.9%, condylar width decreased 13.7%, and the posterior condylar slope was 22% shorter. TPS analysis showed increased antegonial notching, a vertically expanded symphysis, and a collapsed and more horizontal condyle in the BCBC group. The combination of the above methods was very helpful in assessing mandibular morphology and showed that BCBC might be related not only to changes in the condyle, but may dictate changes in the rest of the mandible as well.