Accuracy and head positioning effects on measurements of anterior tooth length using 3-dimensional and conventional dental panoramic radiography.

INTRODUCTION: The purposes of this study were to examine the accuracy and the head positioning effects on measurements of anterior tooth length using 3-dimensional (3D) and conventional dental panoramic radiography and to investigate whether 3D panoramic radiography is suitable for the evaluation of anterior tooth length. METHODS: A simulated human head was radiographed at 4, 8, and 12 mm displaced positions, and at 5°, 10°, and 15° tilted positions from the standard head position using 3D and conventional panoramic radiography, and also using cone-beam computed tomography. Anterior tooth lengths were measured on the panoramic and cone-beam computed tomography images. The values for the standard head position in the panoramic radiographs were defined as the standard values. Measurement error was defined as the standard value minus the cone-beam computed tomography value on each panoramic radiograph. The head position ratio of the measurement value to the standard value at each head position was calculated. RESULTS: Measurement errors for the 3D panoramic radiographs were significantly smaller than those for the conventional panoramic radiographs. In the 3D panoramic radiographs, the head position ratios at the 4, 8, and 12 mm displaced positions and at the 5° tilted position were within ±5% of the standard value. CONCLUSIONS: Three-dimensional panoramic radiography is suitable for the quantitative evaluation of anterior tooth length with high accuracy.

Separation of novel phosphoproteins of Porphyromonas gingivalis using phosphate-affinity chromatography.

Phosphorylation of serine, threonine and tyrosine is a central mechanism for regulating the structure and function of proteins in both eukaryotes and prokaryotes. However, the action of phosphorylated proteins present in Porphyromonas gingivalis, a major periodontopathogen, is not fully understood. Here, six novel phosphoproteins that possess metabolic activities were identified, namely PGN_0004, PGN_0375, PGN_0500, PGN_0724, PGN_0733 and PGN_0880, having been separated by phosphate-affinity chromatography. The identified proteins were detectable by immunoblotting specific to phosphorylated Ser (P-Ser), P-Thr, and/or P-Tyr. These results imply that novel phosphorylated proteins might play an important role for regulation of metabolism in P. gingivalis.

Analysis of pretreatment factors associated with stability in early class III treatment.

BACKGROUND: The purpose of this study was to identify pretreatment factors associated with the stability of early class III treatment, since most orthodontists start the treatment with their uncertain hypotheses and/or predictions. Subjects consisted of 75 patients with a class III skeletal relationship (ANB < 2° and overjet < 0 mm) who had been consecutively treated with rapid maxillary expansion and facemask and followed until their second phase treatment. The patients were divided into two groups according to whether they showed relapse in follow-up. The stable group maintained their positive overjet (n = 55), and the unstable group experienced relapse with a zero or negative overjet (n = 20). Two general, three dental, and 13 cephalometric pretreatment factors were investigated to determine which factors were associated with stability. RESULTS: Sex, pretreatment age, and anteroposterior functional shift, which were hypothesized as associated factors, were not related to the stability of early class III treatment. Significant differences were detected between the two groups in the horizontal distance between the maxillary and mandibular molars in centric relation. Cephalometric variables, such as the mandibular length (Ar-Me), Wits appraisal, SN to ramus plane angle (SN-Rm), gonial angle, incisor mandibular plane angle (IMPA), and Frankfort plane to mandibular incisor angle (FMIA) showed significant differences between the groups. The horizontal distance was the most influential factor by logistic regression analysis. CONCLUSIONS: Hypothesis (related to sex, age, functional shift) were rejected. Several cephalometric factors related to the mandible were associated with stability. The horizontal distance between the maxillary and mandibular molars in centric relation was the best predictor of early class III treatment relapse.

Influence of dental education on eye gaze distribution when observing facial profiles with varying degrees of lip protrusion.

OBJECTIVES: The purpose of the present study was to investigate the influence of dental education on eye gaze distribution when perceiving facial profile images with varying degrees of lip protrusion. METHODS: Fifty-one subjects with dental education (dental-education group) and 47 without dental education (no-dental-education group) were included in this study. The eye gaze distribution of the subjects was recorded for 10 seconds using a non-contact eye tracker when determining whether or not the subjects judged each various facial profile image inappropriate. The facial profile images had varying degrees of upper-lip and lower-lip protrusion. The frequency of eye fixation (lasting >0.06 seconds) was counted. The duration was measured as the total time of eye fixation. The facial images were divided into 4 regions of interest (ROIs): the forehead (ROI-I); the orbit and nose root (ROI-II); the nose tip and upper lip (ROI-III); and the lower lip and chin (ROI-IV). The frequency and duration of eye fixation on each ROI was compared. RESULTS: The frequency of eye fixation on ROI-II was greater in comparison to ROI-I and ROI-IV. The frequency of eye fixation on ROI-III was also greater in comparison to ROI-I and ROI-IV. The duration of eye fixation on ROI-III in the dental-education group was longer in comparison to the no-dental-education group. CONCLUSIONS: Dental education influenced the eye fixation on the nose tip and upper lip when perceiving facial profile images.

Shear bond strength of orthodontic brackets bonded with different self-etching adhesives.

INTRODUCTION: The purpose of this study was to compare the shear bond strength (SBS) of orthodontic brackets bonded with 4 self-etching adhesives. METHODS: A total of 175 extracted premolars were randomly divided into 5 groups (n = 35). Group I was the control, in which the enamel was etched with 37% phosphoric acid, and stainless steel brackets were bonded with Transbond XT (3M Unitek, Monrovia, Calif). In the remaining 4 groups, the enamel was conditioned with the following self-etching primers and adhesives: group II, Transbond Plus and Transbond XT (3M Unitek); group III, Clearfil Mega Bond FA and Kurasper F (Kuraray Medical, Tokyo, Japan); group IV, Primers A and B, and BeautyOrtho Bond (Shofu, Kyoto, Japan); and group V, AdheSE and Heliosit Orthodontic (Ivoclar Vivadent AG, Liechtenstein). The teeth were stored in distilled water at 37 degrees C for 24 hours and debonded with a universal testing machine. The adhesive remnant index (ARI) including enamel fracture score was also evaluated. Additionally, the conditioned enamel surfaces were observed under a scanning electron microscope. RESULTS: The SBS values of groups I (19.0 +/- 6.7 MPa) and II (16.6 +/- 7.3 MPa) were significantly higher than those of groups III (11.0 +/- 3.9 MPa), IV (10.1 +/- 3.7 MPa), and V (11.8 +/- 3.5 MPa). Fluoride-releasing adhesives (Kurasper F and BeautyOrtho Bond) showed clinically acceptable SBS values. Significant differences were found in the ARI and enamel fracture scores between groups I and II. CONCLUSIONS: The 4 self-etching adhesives yielded SBS values higher than the bond strength (5.9 to 7.8 MPa) suggested for routine clinical treatment, indicating that orthodontic brackets can be successfully bonded with any of these self-etching adhesives.

Shear bond strength of a new fluoride-releasing orthodontic adhesive.

This study evaluated the shear bond strength of stainless steel brackets bonded to enamel with a new fluoride-releasing orthodontic adhesive system. A total of 140 extracted human bicuspids were randomly divided into four groups. Group I (Transbond XT) was a control group in which enamel was etched with phosphoric acid. For the remaining groups, enamel was conditioned with a self-etching primer (SEP): Group II (Transbond Plus), Group III (BeautyOrtho Bond), and Group IV (BeautyOrtho Bond + Salivatect). Stainless steel brackets were bonded to all tooth samples. After which, the samples were stored, thermocycled, tested, and statistically analyzed. Besides bond strength evaluation, the adhesive remnant index (ARI) was also evaluated. The shear bond strengths of Groups II, III, and IV were significantly lower than Group I, and Group II was significantly greater than that of Group III. Concerning ARI scores, no significant differences were found between the groups. Further, no enamel fracture was observed during shear bond test with the new SEP. In conclusion, when enamel was conditioned with the new SEP, the mean values of shear bond strength yielded were lower than when it was etched with 37% phosphoric acid. Nonetheless, these mean values were higher than the average suggested by Reynolds as optimum for clinical treatment.

Spatial relationships between the mandibular central incisor and associated alveolar bone in adults with mandibular prognathism.

OBJECTIVE: To examine if there was any correlation between the labio-lingual inclinations of the mandibular central incisor and the associated alveolar bone, and to investigate the labio-lingual position of the mandibular central incisor root apex in the associated cancellous bone in adults with untreated mandibular prognathism. MATERIALS AND METHODS: High-resolution computed tomography images of the mandible were recorded in 20 adult patients with mandibular prognathism. The labio-lingual inclinations of a central incisor and its associated alveolar bone, the thickness of the associated cancellous bone, and the distance from the central incisor root apex to the inner contour of both the labial and lingual cortical plates were measured. Correlations and differences between the measured variables were tested for statistical significance. RESULTS: The labio-lingual inclination of the central incisor significantly correlated with the labio-lingual inclination of the associated alveolar bone, the thickness of cancellous bone, and the distance from the central incisor root apex to the inner contour of the lingual cortical bone. The distance from the central incisor root apex to the inner contour of the labial cortical plate of bone was significantly smaller than that to the lingual cortical plate. CONCLUSIONS: In adults with untreated mandibular prognathism, when the mandibular central incisor was more lingually inclined, the associated alveolar bone was also more lingually inclined and thinner. The mandibular central incisor root apex was closer to the inner contour of the labial cortical bone than to the lingual cortical bone.

Identification of OmpA-Like Protein of Tannerella forsythia as an O-Linked Glycoprotein and Its Binding Capability to Lectins.

Bacterial glycoproteins are associated with physiological and pathogenic functions of bacteria. It remains unclear whether bacterial glycoproteins can bind to specific classes of lectins expressed on host cells. Tannerella forsythia is a gram-negative oral anaerobe that contributes to the development of periodontitis. In this study, we aimed to find lectin-binding glycoproteins in T. forsythia. We performed affinity chromatography of wheat germ agglutinin, which binds to N-acetylglucosamine (GlcNAc) and sialic acid (Sia), and identified OmpA-like protein as the glycoprotein that has the highest affinity. Mass spectrometry revealed that OmpA-like protein contains O-type N-acetylhexosamine and hexose. Fluorometry quantitatively showed that OmpA-like protein contains Sia. OmpA-like protein was found to bind to lectins including E-selectin, P-selectin, L-selectin, Siglec-5, Siglec-9, Siglec-10, and DC-SIGN. The binding of OmpA-like protein to these lectins, except for the Siglecs, depends on the presence of calcium. N-acetylneuraminic acid (NeuAc), which is the most abundant Sia, inhibited the binding of OmpA-like protein to all of these lectins, whereas GlcNAc and mannose only inhibited the binding to DC-SIGN. We further found that T. forsythia adhered to human oral epithelial cells, which express E-selectin and P-selectin, and that this adhesion was inhibited by addition of NeuAc. Moreover, adhesion of an OmpA-like protein-deficient T. forsythia strain to the cells was reduced compared to that of the wild-type strain. Our findings indicate that OmpA-like protein of T. forsythia contains O-linked sugar chains that can mediate interactions with specific lectins. This interaction is suggested to facilitate adhesion of T. forsythia to the surface of host cells.

Mfa4, an Accessory Protein of Mfa1 Fimbriae, Modulates Fimbrial Biogenesis, Cell Auto-Aggregation, and Biofilm Formation in Porphyromonas gingivalis.

Porphyromonas gingivalis, a gram-negative obligate anaerobic bacterium, is considered to be a key pathogen in periodontal disease. The bacterium expresses Mfa1 fimbriae, which are composed of polymers of Mfa1. The minor accessory components Mfa3, Mfa4, and Mfa5 are incorporated into these fimbriae. In this study, we characterized Mfa4 using genetically modified strains. Deficiency in the mfa4 gene decreased, but did not eliminate, expression of Mfa1 fimbriae. However, Mfa3 and Mfa5 were not incorporated because of defects in posttranslational processing and leakage into the culture supernatant, respectively. Furthermore, the mfa4-deficient mutant had an increased tendency to auto-aggregate and form biofilms, reminiscent of a mutant completely lacking Mfa1. Notably, complementation of mfa4 restored expression of structurally intact and functional Mfa1 fimbriae. Taken together, these results indicate that the accessory proteins Mfa3, Mfa4, and Mfa5 are necessary for assembly of Mfa1 fimbriae and regulation of auto-aggregation and biofilm formation of P. gingivalis. In addition, we found that Mfa3 and Mfa4 are processed to maturity by the same RgpA/B protease that processes Mfa1 subunits prior to polymerization.

Three-dimensional magnetic resonance image of the mandible and masticatory muscles in a case of juvenile chronic arthritis treated with the Herbst appliance.

The present report documents, in a case of juvenile chronic arthritis (JCA) with mandibular retrognathia, three-dimensional (3D) changes in the mandible and the relationship between the mandible and the masticatory muscles resulting from treatment with the Herbst appliance after cessation of growth. Magnetic resonance scanning of the whole head was carried out before and after treatment. The mandible, the masseter, and the medial and lateral pterygoid muscles were segmented bilaterally and reconstructed in 3D for both stages. Superimposition of the datasets was carried out according to anatomical structures in the brain (cranial base). Mandibular superimposition was performed according to the mandibular symphysis and the lower mandibular border. The mandible moved forward and downward relative to the anterior cranial base. In addition, bone apposition was observed at the superior and posterior surfaces of both mandibular condyles and at the roof of the glenoid fossa. The masticatory muscles remained relatively stable in position in relation to the anterior cranial base. To our knowledge, such information in JCA patients has not previously been published in the literature. Using magnetic resonance imaging (MRI), it was possible to gain improved insight into the 3D morphology including soft tissues without the overlap of the surrounding tissues observed in the conventional radiographs. Accordingly, it is suggested that 3D magnetic resonance analysis is a more useful method for the follow-up of the JCA patients than radiographic techniques.

Three-dimensional reconstruction of TMJ MR images: a technical note and case report.

MR images of the temporomandibular joint at occlusion and at various stages of mouth opening were registered and reconstructed three-dimensionally before and after a modified condylotomy in a patient with painful disk displacement. Following the condylotomy, the condyle/disk relationship had become normalized in all three planes of space at closed mouth and during mouth opening. The post-operative distances of the condylar and diskal paths had increased when compared with the preoperative distances. The three-dimensional visualizing method may, besides providing diagnostic advantages, be a valuable tool for qualitative and quantitative documentation of the efficiency of different treatment methods for normalization of the disk/condyle relationship in patients with TMJ disk displacement.

Three-dimensional evaluation of a rare case with multiple impacted teeth using CT.

A 15-year-old patient is presented with 11 impacted teeth including 2 supernumerary teeth, who did not exhibit hereditary or clinical disease. The patient showed the extruded and lingually inclined lower incisors, the anteriorly inclined palatal plane, extremely large curve of Spee, and crowding in the bone. A detailed description of the positional relationship between each impacted tooth and the neighboring tooth was given using the 3D CT-image.

Measurement accuracy with a new dental panoramic radiographic technique based on tomosynthesis.

OBJECTIVE: To investigate measurement errors and head positioning effects on radiographs made with new dental panoramic radiograph equipment that uses tomosynthesis. MATERIALS AND METHODS: Radiographic images of a simulated human head or phantom were made at standard head positions using the new dental panoramic radiograph equipment. Measurement errors were evaluated by comparing with the true values. The phantom was also radiographed at various alternative head positions. Significant differences between measurement values at standard and alternative head positions were evaluated. Magnification ratios of the dimensions at standard and alternative head positions were calculated. RESULTS: The measurement errors were small for all dimensions. On the measurements at 4-mm displacement positions, no dimension was significantly different from the standard value, and all dimensions were within ±5% of the standard values. At 12-mm displacement positions, the magnification ratios for tooth length and mandibular ramus height were within ±5% of the standard values, but those for dental arch width, mandibular width, and mandibular body length were beyond ±5% of the standard values. CONCLUSIONS: Measurement errors on radiographs made using the new panoramic radiograph equipment were small in any direction. At 4-mm head displacement positions, no head positioning effect on the measurements was found. At 12-mm head displacement positions, the measurements for vertical dimensions were little affected by head positioning, while those for lateral and anteroposterior dimensions were strongly affected.

Nasal obstruction causes a decrease in lip-closing force.

OBJECTIVE: To investigate the relationship between nasal obstruction and lip-closing force. MATERIALS AND METHODS: Nasal airway resistance and lip-closing force measures were recorded for 54 Japanese females. The subjects were classified into normal and nasal obstruction groups according to nasal airway resistance values. Differences between the normal and nasal obstruction groups in lip-closing force were tested statistically. Correlation coefficients were calculated between the measures for the normal and nasal obstruction groups. RESULTS: Lip-closing force for the nasal obstruction group was significantly less than for the normal group (P < .05). In the normal group, nasal airway resistance did not correlate with lip-closing force, while in the nasal obstruction group a significant negative correlation was found between nasal airway resistance and lip-closing force (P < .05). CONCLUSIONS: Nasal obstruction is associated with a decrease in lip-closing force. When the severity of nasal obstruction reaches a certain level, the lip-closing force is weakened.

Dual segmental distraction osteogenesis of the midface in a patient with Apert syndrome.

OBJECTIVE: To present orthodontic treatment combined with dual segmental distraction osteogenesis in a patient with Apert syndrome. PATIENT: A 15-year-old boy exhibited severe midfacial hypoplasia with retruded and hypoplastic maxilla and anterior open bite. The patient was treated with a rigid external distraction II system for distraction osteogenesis, a preadjusted edgewise appliance, and a modified maxillary protraction headgear. The concave profile with midfacial hypoplasia was improved. A tight occlusal relationship between maxillary and mandibular teeth was achieved. Postoperative treatment results have been stable for 1 year.

Treatment of severe temporomandibular joint clicking with botulinum toxin in the lateral pterygoid muscle in two cases of anterior disc displacement.

A novel treatment procedure is introduced for severe clicking of the temporomandibular joint (TMJ) associated with anterior disc displacement (ADD), using injections with botulinum toxin (BTX-A) in the lateral pterygoid muscle (LP). It has been suggested that ADD may be caused, precipitated, or maintained by LP activity, but the role of the LP in the dynamics of the TMJ clicking is uncertain. The case report includes 2 women, followed with clinical examinations, TMJ imaging, and electromyography (EMG), in whom local anesthetics in the LP could abolish the clicking for several days. BTX-A block of the LP (30 U Botox, given twice under EMG guidance with 6-month interval) temporarily reduced the action of the muscle, but the clicking was permanently eliminated and did not return during the observation period of 1 year, and a small but distinctive positional improvement in the disc-condyle relationship was obtained. However, the precise mechanisms behind the favourable treatment outcome are unclear.

A stent fabricated on a selectively colored stereolithographic model for placement of orthodontic mini-implants.

The purpose of this report is to present a new method for placing orthodontic mini-implants using a stent fabricated on a selectively colored stereolithographic model. A stent was fabricated that incorporated a guide groove drilled in accordance with the planned direction of the mini-implant. Tooth crowns, gingiva, tooth roots, and the maxillary sinuses were clearly identified in the stereolithographic model. As a result, the stent could be fabricated while taking into account the anatomic characteristics of both the bone interior and the dental surface. A stent fabricated on the selectively colored stereolithographic model is suggested to be a promising device for guiding placement of orthodontic mini-implants adjacent to the tooth roots and the maxillary sinuses.

Report of a patient with hypoglossia-hypodactylia syndrome and a review of the literature.

OBJECTIVE: To present the morphology of the extremities, craniofacial structures, and the oral cavity based on roentgencephalometry and three-dimensional computed tomography and magnetic resonance imaging scanning in a patient with hypoglossia-hypodactylia syndrome, discuss the orthodontic treatment method, and review the literature for the syndrome. PATIENT: The patient was a 6-year-old boy diagnosed with hypoglossia-hypodactylia syndrome at birth. He had hypodactylia as well as micrognathia with steep inclination of the anterior surface of the mandible in relation to the lower mandibular plane. He had missing mandibular incisors with concomitant bone defect limited to the associated alveolar ridge and an absence of any malformations in the mandibular ramus and condylar head. The patient had a bilateral scissors bite with an extremely constricted mandibular dental arch, skeletal Class II jaw relationship with an average mandibular plane angle and maxillary incisors inclined palatally. He had extremely reduced tongue size and hypertrophy of the floor of the mouth. Anomalies of the central nervous system were not observed. There was no evidence of hearing loss.

Rigid external distraction osteogenesis for a patient with maxillary hypoplasia and oligodontia.

OBJECTIVE: In this report, the orthodontic treatment combined with rigid external distraction osteogenesis in a 5.5-year-old girl with midfacial hypoplasia and oligodontia is described. PATIENT: The child presented with a reduced maxilla, protruding lower lip, skeletal Class III jaw relationship with a low mandibular plane angle, a short and flattened nose, anterior crossbite, and aplasia of 16 permanent teeth. The patient was treated with rigid external maxillary distraction osteogenesis, maxillary protraction headgear, and Class III elastics. Following treatment, the maxilla was displaced in a forward direction with new bone formation at the tuberosities and the mandible rotated backward in relation to the anterior cranial base. The anterior crossbite was corrected, and the skeletal jaw relationship changed from a Class III to a Class I skeletal pattern. The soft tissue facial profile showed that the nasal projection had been increased, the nasolabial angle increased, and the lower lip protrusion was reduced. Postoperative treatment results were acceptable. CONCLUSION: This report documents that early maxillary advancement with rigid external osteogenesis offers a promising treatment alternative for a very young patient with maxillary hypoplasia and oligodontia.

Craniofacial morphology in an unusual case with nasal aplasia studied by roentgencephalometry and three-dimensional CT scanning.

OBJECTIVE: To examine the three-dimensional morphology of internal structures of the craniofacial region and present the orthodontic problems in an unusual case with nasal aplasia. PATIENT: The patient was an 11.5-year-old boy with aplasia of the nose and nasal cavity with extremely constricted nasopharyngeal airway. He did not have mental or somatic retardation. The patient had dacryostenosis. The morphology of the craniofacial structures was characterized by absence of septal structures, including cribriform plate, perpendicular plate of ethmoid bone, vomer, and septal cartilage; bony hypotelorism; midface hypoplasia; short and retrognathic maxilla with Class III jaw relationship; average mandibular plane angle; high arched palate; severe anterior open bite with bilateral posterior crossbites; and dental anomalies (agenesis of four maxillary permanent teeth, microdontia, taurodontism, and short roots). Thus, the patient had characteristic dentofacial phenotype, which might be caused by a combination of the primary anomaly and the functional disturbances secondary to the nasal obstruction.