Increase of homogenous new bone formation using osteoinductive factor rhGDF-5 during sinus floor augmentation in Goettingen Minipigs.

OBJECTIVES: The aim of this study was to test the hypothesis that recombinant human growth and differentiation factor-5 (rhGDF-5) induces an increased and homogenous distribution of new bone formation across the entire volume of sinus floor augmentation in 12 Goettingen Minipigs. MATERIAL AND METHODS: In a randomized split-mouth design, one maxillary sinus was augmented with the bone substitute ß-TCP, whereas a combination of ß-TCP and the osteoinductive growth factor rhGDF-5 was used on the contralateral side. To evaluate the influence of dose and time on the effectiveness of the factor, two different concentrations of rhGDF-5 (400 µg and 800 µg) and healing periods (4 and 12 weeks) were each analysed. RESULTS: After 4 weeks, a homogenous gradient of bone formation could be observed for all dosage groups, with decreasing bone density from the local bone towards the sinus membrane. Both test groups, however, achieved a higher total level of bone formation compared with the control group, which was only significant in the low-dose group (P = 0.0184). After 12 weeks, the influence of the growth factor significantly depends on the region (P = 0.023). In the low-dose group, the new bone formation did not differ significantly within the examined regions of the graft (P = 0.1118), suggesting a homogeneous bone formation over the entire augmentation. The gradient of the high-dose group was similar to the control group with a decrease of local bone development. CONCLUSIONS: rhGDF-5 delivered on a ß-TCP scaffold material leads to an increase in homogeneous new bone formation across the entire volume of the sinus floor augmentation.

Influence of synthetic polyethylene glycol hydrogels on new bone formation during mandibular augmentation procedures in Goettingen minipigs.

Polyethylene glycol hydrogels (PEG) have been used as slow release carrier for osteoinductive growth factors in order to achieve a retarded delivery. However, there have been concerns about negative effects on bone regeneration. This study aims to test whether PEG hydrogels themselves affect new bone formation (NBF), when used as a carrier during mandibular augmentation procedures. In a randomized split-mouth design, bilateral mandibular bone defects were surgically created in 12 Goettingen minipigs, and subsequently augmented, using PEG hydrogel on one side of the mandible. The contralateral sides, without PEG, served as controls. After 4 and 12 weeks, bone formation was evaluated in six animals each. A comparison of the data, using a three-way analysis of variance (ANOVA), revealed a significant effect of the healing time and the region of the graft on the distribution and enhancement of NBF (P < .0001, respectively). Although a 0.3% (95%-CI [-5.5; 4.8]) lower volume density of newly formed bone could be observed over all PEG hydrogel sections, in contrast to the contralateral controls, the analysis revealed no clinically significant effects of the PEG hydrogel treatment on the total level (P = 0.90), and the distribution of NBF (P = 0.54). In conclusion, PEG hydrogels do not affect NBF when used as a carrier for osteoinductive growth factors during mandibular augmentation procedures.

Mandibular reconstruction using a calcium phosphate/polyethylene glycol hydrogel carrier with BMP-2.

AIM: To test the hypothesis that a synthetic hydroxyapatite/ß-tricalcium phosphate (HA/TCP) construct combined with polyethylene glycol (PEG) hydrogel including recombinant human bone morphogenetic proteins-2 (rhBMP-2) enhances new bone formation compared with bone morphogenetic proteins-2 (BMP-2) delivered using the HA/TCP construct alone. MATERIAL AND METHODS: Bilateral mandibular partial thickness 20 × 8 × 8 mm (L × W × H) alveolar defects were surgically created in the edentulated posterior mandible in 18 female minipigs. Randomized into two groups of nine animals each, the alveolar defects either received HA/TCP or HA/TCP/PEG with or without BMP-2 (105 µg/defect) in contra-lateral sites using a split-mouth design. Primary outcome, bone density (%) within four regions of interest, was evaluated following a 4-week healing interval when the animals were killed for histometric analysis. RESULTS: Bone morphogenetic proteins-2 loaded onto HA/TCP constructs significantly enhanced new bone formation compared with HA/TCP controls. Adding PEG apparently obstructed BMP-2 induced bone formation. CONCLUSION: Polyethylene glycol compromises the osteogenic effect of BMP-2.

Torquing an upper central incisor with aligners--acting forces and biomechanical principles.

The forces delivered by aligners during torquing have still not been investigated. The purpose of this study was to measure the forces delivered to an upper central incisor during torquing with three different materials of the same thickness, and to describe the biomechanical principles of torquing with aligners. Five identical appliances were manufactured from each of three materials, all with a thickness of 1.0 mm (Ideal Clear®, Erkodur®, and Biolon®). An upper central incisor, as part of the measuring device, was torqued in defined steps in the vestibular and palatal directions with the respective appliance in place. For statistical analysis, the resulting forces, Fx (forces acting in the palatal and facial directions) and Fz (intrusive force as a side-effect) at a displacement of ±0.15 and ±0.8 mm from the tooth at the gingival margin were calculated. The mean Fx forces for ±0.15 mm displacement ranged from -1.89 N [standard deviation (SD) 0.48] to 0.11 N (SD 0.1). The mean Fz forces were between -0.97 N (SD 0.57) and -0.07 N (SD 0.22). The highest intrusive forces were measured during palatal displacement of the measuring tooth. An influence of direction of displacement on the levels of force was observed, especially for Fz at the greater displacement of ±0.8 mm. In relation to the intended amount of root movement during torquing, aligners tend to 'lift up' and therefore no effective force couple can be established for further root control. The force delivery properties are also influenced by the material used and the shape of the tooth.

Sinus floor augmentation with recombinant human growth and differentiation factor-5 (rhGDF-5): a pilot study in the Goettingen miniature pig comparing autogenous bone and rhGDF-5.

AIM: The aim of this study was to test the hypothesis that recombinant human growth and differentiation factor-5 (rhGDF-5) in combination with a beta-tricalcium phosphate (beta-TCP) scaffold material results in superior bone formation in sinus floor augmentations in miniature pigs compared with a particulated autogenous bone graft combined with the scaffold material. MATERIAL AND METHODS: Six adult female Goettingen minipigs underwent a maxillary sinus floor augmentation procedure. In a split-mouth design, the sinus floors were augmented with beta-TCP mixed with autogenous cortical bone chips, in a ratio of approximately 1 : 1, on one side. The contralateral test site was augmented using beta-TCP coated with two concentrations of rhGDF-5 (400 microg rhGDF-5/g beta-TCP or 800 microg rhGDF-5/g beta-TCP; three animals in each case). Simultaneously, one dental implant was inserted into each sinus floor augmentation. After 12 weeks, a histological and histomorphometric assessment of non-decalcified histological specimens was made. RESULTS: There were significantly higher mean values of volume density of newly formed bone using beta-TCP coated with two concentrations of rhGDF-5 (400 microg: 32.9%; 800 microg: 23.9%) than with the corresponding control (autogenous bone/beta-TCP) (14.6%, 12.9%) (P=0.012, P=0.049). The bone-to-implant contact rates (BIC) were significantly enhanced in test sites (400 microg: 84.2%; 800 microg: 69.8%) compared with the corresponding control sites (24.8%, 40.8%) (P=.027, P=.045). CONCLUSION: rhGDF-5 delivered on beta-TCP significantly enhanced bone formation compared with beta-TCP combined with autogenous bone in sinus lift procedures in miniature pigs.

Initial forces generated by three types of thermoplastic appliances on an upper central incisor during tipping.

The force properties of thermoformed appliances have not been systematically investigated. Therefore, the aim of the present study was to quantify the forces delivered by thermoplastic appliances manufactured from three different materials, with the same thickness, on a central upper incisor, during tipping. Five identical appliances were manufactured from three different materials all with a thickness of 1.0 mm (Ideal Clear, Erkodur, and Biolon). For measuring the forces, an isolated measuring tooth, as part of a standardized resin model incorporated in a newly developed measuring device, was tipped in nine 2.7 arc minute (0.04629 degree) steps, from 0 to 0.416 degrees in the vestibular and palatal directions around a rotational axis through the virtual apex, after positioning an appliance on the model. For statistical analysis, the force components Fx/tipping and Fz/intrusion at a displacement of +/-0.151 mm from the incisor edge were determined. Means and standard deviations (SDs) were calculated. The Kruskal-Wallis test for overall effects and the Wilcoxon two-sample test for individual group pairings were used (P < 0.05 significance level). The mean Fx forces ranged from -2.82 N (SD 0.62) to 5.42 N (SD 0.56). The mean Fz forces were between -0.14 N (SD 0.52) and -2.3 N (SD 0.43). The highest intrusive forces were measured during vestibular displacement of the measuring tooth. The forces delivered by the Biolon appliance were found to be much greater (P < 0.01) than those of the other materials. The forces delivered by the materials investigated were mostly higher than those stated in the literature.

Mandibular bone repair by implantation of rhBMP-2 in a slow release carrier of polylactic acid--an experimental study in rats.

The aim of the present study was to test the hypothesis that human recombinant bone morphogenic protein 2 (rhBMP-2) implanted in a slow release carrier of polylactic acid (PLA) can repair a non-healing defect in the rat mandible and maintain the thickness of an augmented volume. p-DL-lactic acid discs were produced and loaded with 48 and 96 microg rhBMP-2 and inserted into non-healing defects of the mandible of 45 Wistar rats. Fifteen rats received implants with 96 microg rhBMP-2 (Group 2), 48 microg rhBMP-2 (Group 1) and blank implants without BMP (Group 0) each on one side of the mandible. Unfilled defects of the same size on the contralateral sides of the mandibles served as empty controls. After 6, 13 and 26 weeks, implants of each group were retrieved from five animals each and submitted to flat panel detector computed tomography. Bone formation and thickness of augmentation was assessed by computer-assisted histomorphometry. In Group 2 significantly more bone was produced than in Group 1. Implants of Group 1 induced significantly more bone than the blank controls only after 6 weeks, whereas the difference was not significant after 13 and 26 weeks. Differences between Group 2 and Group 1 were clearly significant after 26 weeks. The thickness of bone tissue was maintained in Group 2 whereas it decreased in Group 1 and was negligible in Group 0. It is concluded that the PLA implants with 96 microg rhBMP-2 were able to bridge a non-healing defect in the rat mandible and maintained the thickness of an augmented volume. However, continuous supply of osteogenic signals appears to be required to compensate for adverse effects during polymer degradation.

Sinus floor augmentation with recombinant human growth and differentiation factor-5 (rhGDF-5): a histological and histomorphometric study in the Goettingen miniature pig.

AIM: The aim of this study was to test the hypothesis that recombinant human growth and differentiation factor-5 (rhGDF-5) enhances bone formation in sinus floor augmentations in miniature pigs. MATERIAL AND METHODS: The maxillary sinus floors in 12 adult female Goettingen minipigs were augmented with beta-tricalcium phosphate (beta-TCP) on one side. The contralateral test side was augmented using two concentrations of rhGDF-5 (400 microg rhGDF-5/g beta-TCP; 800 microg rhGDF-5/g beta-TCP) delivered on beta-TCP (six animals each). One dental implant was inserted into each sinus floor augmentation. After 4 and 12 weeks, histological and histomorphometric assessment of non-decalcified histological specimens was performed. RESULTS: The results showed significantly higher mean values of volume density (VD) of newly formed bone using the concentration of 400 microg/g beta-TCP (22.8%) compared with the respective control (8%) after 4 weeks (P=0.05). The bone-to-implant contact rates were also significantly enhanced after 4 weeks between test sites (400 microg: 41.9%; 800 microg: 40.6%) and control sites (400 microg: 7.8%; 800 microg: 16.4%) (400 microg: P=0.024; 800 microg: P=0.048). CONCLUSION: It is concluded that rhGDF-5 delivered on beta-TCP significantly enhanced early bone formation compared with beta-TCP alone in sinus lift procedures in miniature pigs.

Optimizing preparation design for metal-free composite resin crowns.

STATEMENT OF PROBLEM: Although composite resin materials are used for posterior crown restorations, the influence of preparation design, material thickness, convergence angle, and method of cementation on fracture resistance remains unclear. PURPOSE: The purpose of this in vitro study was to test the hypothesis that minimal preparation designs provide an acceptable level of fracture resistance for posterior composite resin crowns. MATERIAL AND METHODS: Nonreinforced Artglass composite resin crowns (n=128) were fabricated on human molars in 16 test groups (n=8). Axial tooth preparation included a 1-mm-deep shoulder or a 0.5-mm chamfer preparation, whereas occlusal reduction was either 0.5 mm or 1.3 mm. The total angle of convergence was 4 or 11 degrees and the crowns were cemented either with glass ionomer cement (Ketac Cem) or resin cement (2bond2). After 10,000 thermal cycles, crowns were vertically loaded until failure occurred; load was measured in newtons. Statistical analysis was performed by a 4-way ANOVA (alpha=.05). RESULTS: Statistical analysis revealed significant effects of occlusal thickness (P<.001), cement (P<.001), preparation design (P=.011), and convergence angle (P=.001) on the fracture resistance of the composite crowns. For composite resin crowns with an occlusal thickness of 0.5 mm, the resistance to fracture was lower than for crowns with a 1.3-mm thickness. Fracture resistance was greater when resin cement was used, and greater for the chamfer finish line than for the shoulder finish line. Use of a greater total convergence angle reduced fracture resistance. CONCLUSIONS: Fracture resistance of composite resin crowns was significantly improved by increasing the occlusal thickness of the crowns, by using resin cement, and by reducing the total convergence angle.

The use of a neodymium-iron-boron magnet device for positioning a multi-stranded wire retainer in lingual retention--a pilot study in humans.

The aim of this study was to evaluate the time requirement of a newly developed device made of neodymium-iron-boron (NdFeB) magnets for positioning a multi-stranded, canine-to-canine retainer during bonding compared with dental floss and a transfer tray. Forty-five patients aged between 12 and 33 years (26 male, 19 female) previously treated with fixed appliances were enrolled in the study. The patients were randomly allocated to three groups (15 per group). For each group a mandibular canine-to-canine retainer of 0.018 inch Dentaflex multi-stranded wire (Dentaurum) was prefabricated for each patient on a cast. The bonding procedure was identical, except for the method of positioning the wire during adhesive fixation: group A dental floss, group B a small prefabricated transfer tray of dental resin and group C the NdFeB magnet device. For each group, the time required for the complete bonding process was measured. Kruskal-Wallis and Wilcoxon-Mann-Whitney tests were used for group and pairwise comparisons, respectively. The three methods required statistically significant different times (P < 0.001). The Wilcoxon-Mann-Whitney test revealed that wire positioning with the magnet device was significantly faster [4.98 minutes; standard deviation (SD) 0.68 minutes] than with dental floss (7.65 minutes, SD 1.14 minutes; P = 0.0001) or with transfer tray (5.75 minutes, SD 0.57 minutes; P = 0.001). The NdFeB magnet device is a timesaving appliance for positioning a multi-stranded, canine-to-canine retainer during bonding when compared with dental floss and an individually prefabricated transfer tray.

Removable thermoplastic appliances modified by incisal cuts show altered biomechanical properties during tipping of a maxillary central incisor.

BACKGROUND: The present study aimed to evaluate the force delivery of removable thermoplastic appliances (RTAs), modified by different sized incisal cuts, during tipping of a maxillary central incisor in palatal and vestibular direction. METHODS: Forty-five RTAs from three different materials (Biolon®, Erkodur®, Ideal Clear®) of the same thickness (1 mm) were used. Analysis was performed on a separated maxillary central incisor which was part of a resin model with a complete dentition. In 15 RTAs, of different material, a cut was inserted at the incisal edge of tooth 11. In 15 other appliances, the cut was extended to teeth 12 and 21. Fifteen aligners remained uncut. The experimental tooth was tipped starting from the zero position in 0.05° steps to a maximal deflection of ± 0.42° of the incisal edge in vestibular and palatal direction, after positioning the RTA onto the model. RESULTS: The horizontal (Fx) and the vertical (Fz) force components were decreased by approximately half with increasing cut size. Fz values changed during palatal tipping from a weak intrusive force, for aligners without cut, to an extrusive force with increasing cut size. Compared to both other materials used (Erkodur® and Ideal Clear®), the Biolon® aligners showed significantly higher Fx and Fz values (p < 0.0001, respectively). CONCLUSIONS: RTAs modified by different sized incisal cuts show altered biomechanical properties and an inversion of the vertical force component, during tipping of a maxillary central incisor.

Osteoblast-like cells with different embryologic origins behave differently in increasing zoledronic acid concentrations: a pilot study in pigs.

OBJECTIVE: We compared the intraindividual effects of increasing zoledronic acid (ZA) concentrations on osteoblast-like cells with different embryologic origins. STUDY DESIGN: Cultured osteoblast-like cells from mandible and iliac crest bone samples of domestic pigs were exposed to increasing concentrations of ZA (0, 10-8, 10-6, and 10-4 M). Proliferation was assessed by cell counting. Receptor activator of nuclear factor kB ligand and osteoprotegerin (OPG) messenger RNA expression were assessed at 0, 1, 4, 7, and 10 days. RESULTS: The OPG expression level was higher in the iliac crest than in the mandible. Neither ZA concentration nor the cells' origin affected the expression of receptor activator of nuclear factor kB ligand. At 10-6 M, OPG expression from both locations reached the same level after 7 days of cultivation, as OPG expression increased to a greater extent in the mandible in comparison to the iliac crest. CONCLUSION: Cultured mandibular osteoblast-like cells reacted more sensitively to high ZA concentrations than did osteoblast-like cells from the iliac crest.

Primary stability and osseointegration of dental implants in polylactide modified bone - A pilot study in Goettingen minipigs.

The present study aimed to evaluate primary stability (PS) and osseointegration of dental implants in polylactide [70/30 poly(l-lactide-co-d, l-lactide); (PLDLA)] modified bone in 30 Goettingen minipigs. Each animal received three implants per jaw quadrant. In a split-mouth design, one side of the maxilla and mandible was randomly allocated to the experimental treatment (PLDLA applied into the drill hole before implantation), while the contralateral sides served as intraindividual controls (no PLDLA applied). The required insertion torque and the implant stability quotient (ISQ) were measured during implantation. ISQ, volume density (VD) of new bone formation (NBF), and the bone-implant contact (BIC) were evaluated at the end of the observation period (1, 3, 6, 12, and 24 months, respectively) in six animals each. Across all study groups, the PLDLA treatment resulted in a) a comparable insertion torque, b) an equivalent ISQ, c) a reduced BIC, and d) a reduced VD of NBF, as opposed to the untreated controls. In conclusion, the PLDLA treatment did not affect the PS, but rather led to an impaired osseointegration, which was particularly strong in the compact mandibular bone, and decreased in the spongious maxillary bone. PLDLA induced anchoring in spongious bone should be evaluated in further investigations.

Reduced somatosensory impairment by piezosurgery during orthognathic surgery of the mandible.

PURPOSE: This clinical trial aimed to test the hypothesis that piezosurgery causes reduced nerval irritations and, thus, reduced somatosensory impairment when used in orthognathic surgery of the mandible. METHODS: To this end, 37 consecutive patients with Angle Class II and III malocclusion were treated using bilateral sagittal split osteotomies (BSSO) of the mandible. In a split mouth design, randomized one side of the mandible was operated using a conventional saw, while a piezosurgery device was used on the contralateral side. In order to test the individual qualities of somatosensory function, quantitative sensory testings (QSTs) were performed 1 month, 6 months and 1 year after surgery. RESULTS: A comparison of the data using a two-way analysis of variance (ANOVA) revealed a significant reduction in postoperative impairment in warm detection threshold (WDT) (P = 0.046), a decreased dynamic mechanical allodynia (ALL) (P = 0.002) and a decreased vibration detection threshold (VDT) (P = 0.030) on the piezosurgery side of the mandible as opposed to the conventionally operated control side. In the remaining QSTs, minor deviations from the preoperative baseline conditions and a more rapid regression could be observed. CONCLUSIONS: Piezosurgery caused reduced somatosensory impairment and a faster recovery of somatosensory functions in the present investigation.

Measurement of the midpalatal suture width.

OBJECTIVE: To conduct a pilot study to investigate the potentiality to determine the midpalatal sutural width radiographically with a flat-panel volume computed tomography (fpVCT) in a porcine model. MATERIALS AND METHODS: Bone samples from the midpalatal suture of five young (16 weeks) and five old (200 weeks) sus scrofa domestica were gathered. The midpalatal suture width was measured via fpVCT and compared to respective histological preparations. Results with P < .05 were considered significant. RESULTS: The data obtained by fpVCT and by histomorphometric analysis reveal a highly significant age dependency of the measured suture width (both P < .0001), with lower suture width values in older subjects compared to the younger group. The averaged suture widths measured in the fpVCT images shows a distinctively higher mean compared to the histomorphometric data with high statistical significance (P < .0001). The evaluated difference between both methods was almost constant. CONCLUSION: fpVCT is a powerful tool for determining midpalatal sutural width.

The influence of occlusal forces on force delivery properties of aligners during rotation of an upper central incisor.

OBJECTIVE: To determine the forces and moments delivered to a maxillary central incisor during rotation with aligners when a simulated occlusal force generated during swallowing acts on the appliance. MATERIALS AND METHODS: Five identical appliances were manufactured from four different starting materials (Erkodur 0.8 mm and 1.0 mm; Biolon 0.75 mm and 1.0 mm). An upper central incisor fixed in a measuring device was rotated around its central axis in 0.5-degree steps up to ±10 degrees with the appliance fixed in place. An occlusal force of 30 N generated during swallowing was simulated with a weight positioned on the appliance. For statistical analysis, the moments Tz (rotation) and forces Fz (intrusion) at a deflection of ±0.34 mm to the incisor edge (±5 degrees rotation) were tested. Means and standard deviations for Tz and median and 25% and 75% quartiles for Fz were calculated. An analysis of variance was performed. RESULTS: The simulated occlusal force increased the measured intrusive force Fz (maximum with a weight, -3.7 N [-3.7, -2.4]; minimum without a weight, -1.3 N [-1.4, -1.1]) and the rotary moment Tz (maximum with a weight, -50.8 Nmm [±0.8]; minimum without a weight, 18.2 Nmm [±0.9]) significantly in all cases (P < .01). This was found for all materials measured and for both directions of rotation. CONCLUSION: During rotation with aligners, a simulated occlusal force increases the intrusive force and the rotary moment. The biological adverse side effects of these phenomena remain unclear, especially in patients with periods of bruxism.

Accuracy of fit of 3-to-3 retainers after adhesive fixation using a neodymium-iron-boron magnet chain.

BACKGROUND AND OBJECTIVE: Six-base retainers are often used to prevent tertiary crowding. To minimize shear stress on the retainer, these should be fitted as precisely as possible. The aim of this study was to compare the accuracy of fit of 6-base retainers after adhesive fixation using a neodymium-iron-boron (NdFeB) magnet chain or a resin positioning aid. MATERIALS AND METHODS: A 6-base retainer was prepared for 40 pseudo-anonymous lower jaw models (2 × 20). Temporary fixation was performed with a resin positioning aid or a NdFeB magnet chain. The adhesive fixation of the retainers was randomized. The area and vertical distance between wire and teeth were determined by histomorphometry. The results were evaluated by ANOVA. The probability of error was specified as 5%. RESULTS: With the magnetic chain method, the area was significantly smaller than with the positioning aid (p = 0.0125). The difference between the two methods was ca. 1.3 mm². Moreover, the measured distance was affected significantly by the method used (p < 0.0002). With the magnet chain, the distance between the tooth and retainer was reduced by a mean of 0.05 mm. Conclusion. The fit of the retainer wire improves somewhat when the NdFeB magnet chain is used even though the wire is not as precisely positioned as it would be with a custom-made positioning aid.

Detection and size differentiation of simulated tooth root defects using flat-panel volume computerized tomography (fpVCT).

OBJECTIVE: Our aim was to evaluate the capacity of flat-panel volume computerized tomography (fpVCT) to enable the observer to detect and differentiate 3 different sizes of simulated tooth root defects in radiographs. STUDY DESIGN: Three simulated tooth root defects of different sizes and a defect-free area (160 sites in total) were randomly distributed on the buccal and lingual surface of 20 mandibular premolar roots of Sus scrofa domestica with round burs. For the imaging of the specimens, an fpVCT prototype was used. Findings were evaluated by 3 observers. RESULTS: Cavity 0 (no lesion) was correctly identified in 53%, cavity 1 in 69%, cavity 2 in 96%, and cavity 3 in 89%. Altogether, the simulated cavities were classified in a correct manner in 77%. The values were compared using receiver operating characteristic curves. The area under the curve (AUC) for cavity 0 versus the pooled results for cavities 1-3 was found to be 0.72. The AUC for the pooled results for 0-2 (no pathologic impact) versus cavity 3 (potential pathologic impact) was 0.94. There was no significant dependence of the results on the observer (P = .37). Results with P < .05 were considered to be significant. CONCLUSIONS: Flat-panel volume computerized tomography, which is currently used only as a research tool, has a high potential in detection and differentiation at an early stage of external root resorption cavities with pathologic relevance..

Imaging of the midpalatal suture in a porcine model: flat-panel volume computed tomography compared with multislice computed tomography.

OBJECTIVE: An investigation was conducted to compare the image quality of prototype flat-panel volume computed tomography (fpVCT) and multislice computed tomography (MSCT) of suture structures. STUDY DESIGN: Bone samples were taken from the midpalatal suture of 5 young (16 weeks) and 5 old (200 weeks) Sus scrofa domestica and fixed in formalin solution. An fpVCT prototype and an MSCT were used to obtain images of the specimens. The facial reformations were assessed by 4 observers using a 1 (excellent) to 5 (poor) rating scale for the weighted criteria visualization of the suture structure. A linear mixed model was used for statistical analysis. Results with P < .05 were considered to be statistically significant. RESULTS: The visualization of the suture of young specimens was significantly better than that of older animals (P < .001). The visualization of the suture with fpVCT was significantly better than that with MSCT (P < .001). CONCLUSION: Compared with MSCT, fpVCT produces superior results in the visualization of the midpalatal suture in a Sus scrofa domestica model.