Physical properties of root cementum: Part 25. Extent of root resorption after the application of light and heavy buccopalatal jiggling forces for 12 weeks: A microcomputed tomography study.

INTRODUCTION: The aims of this study were to evaluate with microcomputed tomography the orthodontically induced inflammatory root resorption in premolars caused by buccopalatal jiggling movement with light and heavy forces and to compare it with the resorption caused by equivalent but continuous buccal forces. METHODS: The sample consisted of 60 maxillary first premolars collected from 30 patients (15 girls, 15 boys; ages, 13-18 years) who required orthodontic treatment with extractions. They were divided into 3 groups of 10 patients. Light (25 g) or heavy (225 g) buccal tipping orthodontic forces were randomly assigned on the maxillary right or left quadrant with either continuous buccal (positive controls) or buccopalatal jiggling forces for 12 weeks. At the end of the experimental period, the teeth were carefully extracted and processed for 3-dimensional imaging and volumetric evaluations of resorption craters. Data were analyzed with Wilcoxon signed rank tests. RESULTS: There was no statistically significant difference between positive control light (P = 0.0173) and heavy (P = 0.0173) continuous forces and jiggling forces for both force magnitudes. However, statistically significant differences were observed between heavy and light jiggling forces (P = 0.038), with heavy jiggling forces causing greater total root resorption than light jiggling forces. CONCLUSIONS: Light and heavy jiggling forces in the buccopalatal direction did not cause significantly different amounts of root resorption when compared with continuous forces of the same magnitude. On the other hand, light jiggling forces resulted in less root resorption than heavy jiggling forces.

Bone microarchitecture at oral implant sites in ectodermal dysplasia (ED): a comparison between males and females.

OBJECTIVE: The aim of this study was to analyse the microarchitecture of bone in association with implant placement in young ectodermal dysplasia (ED) patients. The general hypothesis was that the structural and morphological features of bone microarchitecture are different between males and females, which may influence clinical outcomes. MATERIALS AND METHODS: The bone harvesting is not additionally invasive, as the procedure was made at the time and site of implant placement. Twenty one samples (8 female, 13 male) were harvested from nine ED participants whose age ranged between 14 and 21 years and specified by the site of harvesting. Micro-CT analysis at 5 µm resolution was conducted on each sample. Specialized CT analysis of the three-dimensional (3-D) bone microstructure was made to compare structural parameters. In addition, two bone samples (one male, one female) were sent to the University of Michigan and analysed at 9 µm resolution. RESULTS: No significant difference was found between male and female samples. Bone analysis of particular sites revealed that bone-specific surface (BS/BV) was found to be significantly higher in male than in female samples, whilst the mean values of 10 parameters, the grey scale value histograms and 3-D visualization showed that female samples had higher compact density than male samples. CONCLUSION: Microstructural analyses indicated that female ED bone was more compact and with greater trabecular connectedness than male bone. These features may enhance resistance to external force transfer of mastication compared with male bone. Further bone samples from other jaw bone areas will provide information on whether there are regional differences in jawbone quality and quantity, which may influence implant treatment outcomes, as well as follow-up analyses of treatment outcomes.

Physical properties of root cementum: part 23. Effects of 2 or 3 weekly reactivated continuous or intermittent orthodontic forces on root resorption and tooth movement: a microcomputed tomography study.

INTRODUCTION: The force application period is a modifiable factor in root resorption. There is still ambiguity if the continuity of force application is advantageous in terms of root resorption and tooth movement. In this prospective randomized clinical trial, we compared the effects of 2 reactivation periods of controlled-intermittent and continuous forces on root resorption and tooth movement. METHODS: Thirty-two patients were randomly divided into 2 groups: 2 weekly and 3 weekly reactivations. A split-mouth setup was used for the intermittent and continuous force comparisons. The intermittent force was designed with a pause of 3 days before each reactivation of the springs. A buccally directed tipping force (150 g) was generated with 0.017 × 0.025-in Beta III Titanium cantilever springs (3M Unitek, Monrovia, Calif). After the extractions, surface analysis was performed with microcomputed tomography (model 1172; SkyScan, Aartselaar, Belgium) and specially designed software (CHull2D) for direct volumetric analysis. Buccal premolar movement was also measured on the images of the study casts. RESULTS: Continuous forces produced more resorption than intermittent forces on the total volumes in both groups. A significant difference was found for the 3-weekly group only (P <0.01) on the cervical-mesial (P <0.01) and cervical-buccal (P <0.05) compression regions. In the 2-weekly group, differences were evident in the middle-distal (P <0.05) and middle-lingual (P <0.05) tension regions. Continuous forces produced significantly more tooth movement than did the intermittent forces for both the 2-weekly (P <0.01) and the 3-weekly (P <0.001) regimens. Significant differences were not observed between the 2 intermittent force regimens regarding root resorption and tooth movement. CONCLUSIONS: Intermittent force causes less root resorption and tooth movement than continuous force. Root resorption decreases irrespective of the timing of reactivation, when a pause is given. On the other hand, timing of reactivation might have critical importance on continuous force applications, since 2 weekly reactivations produced faster tooth movement with similar root resorption when compared with intermittent force.

Physical properties of root cementum: part 21. Extent of root resorption after the application of 2.5° and 15° tips for 4 weeks: a microcomputed tomography study.

INTRODUCTION: Microcomputed tomography offers a unique opportunity to accurately examine orthodontically induced inflammatory root resorption. The aims of this study were to quantify, in 3 dimensions, the amount of root resorption caused by placing heavy and light distal root tipping forces on premolars and to compare the prevalence of root resorption in different areas of the tooth. METHODS: Thirty maxillary first premolars from 15 patients who were to have these teeth extracted as part of their orthodontic treatment were selected for this study. Each tooth in the same patient was randomly chosen to have either a 2.5° or a 15° distal root tipping bend placed for 4 weeks. After the experimental period, the teeth were extracted according to a strict protocol to prevent damage to the root. They were then imaged by a microcomputed tomography scan x-ray system (SkyScan 1172, SkyScan, Aartselaar, Belgium) and analyzed by software designed for volumetric measurements. RESULTS: A significant difference was found in the amount of total root resorption between light and heavy forces (P = .021). The mean cube root volumes of the resorption craters in the 15° tip-bend group were greater than in the 2.5° tip-bend group. This significance was lost when the tooth was divided into vertical thirds, although a trend was still present. When the areas of expected compression in the periodontal ligament were compared with the areas of expected tension, significance was seen in the apical and cervical thirds only. CONCLUSIONS: Based on this experiment, one can conclude that a 15° distal root tip bend causes more orthodontically induced inflammatory root resorption than a 2.5° distal root tip bend. Furthermore, greater root resorption was found in areas under pressure when compared with areas under tension.

Physical properties of root cementum: Part 18. The extent of root resorption after the application of light and heavy controlled rotational orthodontic forces for 4 weeks: a microcomputed tomography study.

INTRODUCTION: The aim of this prospective randomized clinical trial was to quantitatively measure and compare the locations, dimensions, and volume of root resorption craters in human premolars after the application of controlled light and heavy rotational orthodontic forces over a 28-day (4-week) period. METHODS: Fifteen patients requiring bilateral extraction of maxillary first premolars as part of their orthodontic treatment were recruited for this study. Each patient received a heavy (225 g) rotational force on 1 premolar and a light (25 g) rotational force on the contralateral premolar. Orthodontic rotational forces were applied over 28 days with buccal and palatal cantilever springs; 0.016-inch beta-titanium molybdenum alloys were used to apply the light force and 0.018-inch stainless steel was used for the heavy force. After the 28-day experimental period, the upper first premolars were extracted under stringent protocols to prevent root surface damage. The samples were then scanned using a microcomputed tomography (micro-CT) scan x-ray system (SkyScan 1072, Skyscan, Aartselaar, Belgium), and analyzed using convex hull algorithm (CHULL2D; University of Sydney, Sydney, Australia) software to obtain direct volumetric measurements. RESULTS: The mean volume of resorption craters was 0.42 in the light force group and 0.51 in the heavy force group (P = 0.013). When separated at the root level, the difference in volume of root resorption craters between the 2 groups was significantly different only at the midlevel (P = 0.001). Root resorption craters were consistently detected at the boundaries between the buccal and distal surfaces and the mesial and lingual surfaces. The result supports our hypothesis that positive areas develop significantly more root resorption craters at all 3 levels, as compared with minimal areas (paired t test <0.001). CONCLUSIONS: Heavy rotational forces caused more root resorption than light rotational forces and compression areas (buccal-distal and lingual-mesial surfaces in this study) showed significantly higher root resorption than other areas at all levels of the root.

Physical properties of root cementum: Part 19. Comparison of the amounts of root resorption between the right and left first premolars after application of buccally directed heavy orthodontic tipping forces.

INTRODUCTION: Previous studies have used the right and left sides of the same jaw to compare different force levels, types of movement, and durations of forces. However, the amounts of root resorption have not been compared between the right and left sides after applying the same amount of force. The aims of the study were to quantitatively compare the volumes of the root resorption lacunae between the right and left first premolars to determine whether 1 side can serve as a control to the other and to compare the volumes of root resorption lacunae of the first premolars between the maxilla and the mandible. METHODS: Forty-four first premolars, orthodontically indicated for extraction from 11 patients (left and right maxillary and mandibular first premolars from each) were moved buccally by using beta-titanium-molybdenum alloy 0.017 × 0.025-in cantilever springs with continuous heavy (225 g) force. After the experimental period, the teeth were extracted under a strict protocol to prevent root cementum damage and then analyzed by using a microcomputed tomography scan x-ray system (1172; SkyScan, Aartselaar, Belgium) and specially designed software (Convex Hull 2D, University of Sydney, Sydney, Australia) for direct volumetric measurements. RESULTS: There were no statistically significant differences in the mean cube root volumes of root resorption craters between the right and left sides (P = 0.18) or between the maxillary and mandibular jaws (P = 0.10). There was also no statistical significance for the interception (P = 0.41), which indicated that the jaw and the side had independent effects. CONCLUSIONS: The amount of root resorption on the left and right sides of the jaw were similar in both the maxilla and the mandible. Therefore, for future root resorption studies, it is justifiable to use the split-mouth technique so that teeth from 1 side of the jaw can serve as the controls.

Physical properties of root cementum: Part 16. Comparisons of root resorption and resorption craters after the application of light and heavy continuous and controlled orthodontic forces for 4, 8, and 12 weeks.

INTRODUCTION: Orthodontic force duration can affect the severity of root resorption. The aim of this clinical study was to investigate the amounts of root resorption volumetrically after the application of controlled light and heavy forces in the buccal direction for 4, 8, and 12 weeks. METHODS: The sample consisted of 54 maxillary first premolars in 36 patients (mean age, 14.9 years; 21 girls, 15 boys) who required first premolar extractions as part of their orthodontic treatment. The teeth were allocated into 3 groups that varied in the duration of force application: 4, 8, or 12 weeks. The right or left first premolars were randomly selected to receive 2 levels of forces. A light buccally directed orthodontic force of 25 g was applied to the experimental tooth on 1 side, while a heavy orthodontic force of 225 g was applied on the contralateral premolar. At the end of the experimental period, the teeth were extracted and scanned with the microcomputed-tomography x-ray system. Resorption crater analysis was performed with specially designed software for direct volumetric measurements. RESULTS: Significant differences in the extent of root resorption were found between 4, 8, and 12 weeks of force application (P <0.001), with substantially more severe resorption in the longer force duration groups. The light force produced significantly less root resorption than did the heavy force. CONCLUSIONS: After 4, 8, or 12 weeks of buccally directed orthodontic forces applied on the maxillary first premolars, the volumes of root resorption craters were found to be related to the duration and the magnitude of the forces.

Repair of root resorption 4 and 8 weeks after application of continuous light and heavy forces on premolars for 4 weeks: a histology study.

INTRODUCTION: Repair of root resorption cavities has been studied under light microscopy, scanning electron microscopy, and transmission electron microscopy. The aim of this investigation was to demonstrate the use of microcomputed tomography (micro-CT) to assist in the identification of the region of interest for light microscopy preparation. This study also qualitatively illustrated the root resorption craters with 4 or 8 weeks of retention after 4 weeks of continuous light or heavy orthodontic force application. METHODS: Four patients who required bilateral extractions of maxillary first premolars as part of their orthodontic treatment were divided into 2 groups (groups I and II) of 2. The maxillary left and right first premolars were loaded with light (25 g) or heavy (225 g) orthodontic force for 4 weeks. After 4 or 8 weeks of retention, the maxillary first premolars were extracted. The extracted teeth were investigated with micro-CT. By using 3-dimensional images created by the micro-CT, the largest resorption craters on the buccal and lingual sides were identified. Parasagittal sections of these resorption craters were studied histologically under hematoxylin and eosin staining. RESULTS: The use of micro-CT improved the efficiency and accuracy of histologic techniques. Comparatively, less root resorption was repaired by new cementum after heavy orthodontic force application and short retention time. The reparative processes seemed to depend on time, with longer retention time yielding the most amount of repair. Reparative cementum was a mixture of acellular and cellular cementum. Reparative processes seemed to commence at the central part of the resorption cavity and expand to the periphery. CONCLUSIONS: Root resorption cavities have the potential to repair regardless of the orthodontic force magnitude. Correlative microscopy with micro-CT and conventional light microscopy adds a new dimension to current root resorption investigation techniques.

Physical properties of root cementum: part 12. The incidence of physiologic root resorption on unerupted third molars and its comparison with orthodontically treated premolars: a microcomputed-tomography study.

UNLABELLED: INTRODUCTION Root resorption can occur as a physiologic or a pathologic process, and it is an unwanted side effect of orthodontic treatment. No baseline studies have assessed this phenomenon in the absence of force variables such as mastication, parafunction, and soft-tissue pressure. In this study, we investigated the incidence and quantitative value of root resorption on unerupted third molars with normal development using microcomputed tomography. METHODS: Nine unerupted, nonimpacted maxillary third molars were collected from 6 patients (ages, 19.47 plus /minus 1.89 years). The teeth were examined with microcomputed tomography and compared with teeth from other studies. (The other teeth had been treated with buccally directed light [25 g] or heavy [225 g] forces applied for 28 days, or light [25 g] or heavy [225 g] intrusion forces for 28 days.) RESULTS: Imaging and volumetric analyses showed resorption craters in many locations and with various magnitudes. Analysis of variance was completed by position (P = 0.04), surface (P = 0.07), height (P = 0.045), left or right side of the mouth (P = 0.85), and subject (P = 0.70). The midroot region on the mesial surfaces of the third molars, near the root structure of adjacent erupted second molars, had the greatest statistical significance. When compared with crater volumes of fully erupted first premolars, we found that the unerupted third molar sample had a slightly greater cube root volume per tooth than the erupted first premolars not subjected to orthodontic force and a similar cube root volume per tooth as did first premolars subjected to light (25 g) buccal and intrusive orthodontic forces. CONCLUSIONS: Root resorption as a consequence of orthodontic treatment might be added to a baseline level of root resorption. The elevated results suggest that resorption might occur as part of hard-tissue remodeling and turnover, eruption, or transmission of masticatory forces through the dentition to the alveolar bone.

Physical properties of root cementum: part 11. Continuous vs intermittent controlled orthodontic forces on root resorption. A microcomputed-tomography study.

INTRODUCTION: There is still ambiguity about whether continuous or intermittent orthodontic forces produce more root resorption. This prospective randomized clinical trial was designed to compare root resorption with these 2 force application patterns. METHODS: The sample consisted of 16 maxillary first premolars from 8 patients who required bilateral extractions as part of their orthodontic treatment. In each subject, a fixed experimental appliance was placed on the maxillary teeth on each side, allowing a buccally directed force. The force was generated by a segmental wire of beta-titanium-molybdenum alloy. The first premolar on 1 side received a buccally directed continuous force, and the contralateral premolar received intermittent force. The initial force magnitude for both sides was 225 cN. After 14 days of initial continuous force, the intermittent force application was obtained with subsequently repeated periods until the end of the eighth week of a 3-day rest period followed by a 4-day force application period. Force levels were set to 225 cN at each patient visit. After the experimental period of 8 weeks, the teeth were extracted under a strict protocol to prevent root surface damage and analyzed with a microcomputed-tomography scan system, and specially designed software was used for direct volumetric measurements. RESULTS: Intermittent force produced less root resorption than continuous force (P <0.05). Analysis by position showed that the buccal-cervical region had significantly more root resorption than the other positions (P <0.001), corresponding to a region of compression generated by tipping. CONCLUSIONS: The application of intermittent orthodontic forces of 225 cN for 8 weeks (14 days of force application, 3 days of rest, then 4 days of force application repeated for 6 weeks) caused less root resorption than continuous forces of 225 cN for 8 weeks. Although it might not be clinically practical, compared with continuous forces, intermittent forces might be a safer method to prevent significant root resorption. This regimen, however, could compromise the efficiency of tooth movement.

Physical properties of root cementum: part 14. The amount of root resorption after force application for 12 weeks on maxillary and mandibular premolars: a microcomputed-tomography study.

INTRODUCTION: Orthodontic force magnitude is a primary factor in root resorption. Quantitative studies of root resorption after force application for 4 and 8 weeks have been conducted. In this study, we investigated the root surface topography and the amount of root resorption after the application of controlled light and heavy forces in a buccal direction for 12 weeks. In addition, the amounts of root resorption when controlled light and heavy forces were applied to the maxillary and mandibular first premolars were quantified. METHODS: Forty maxillary and mandibular first premolars were collected from 10 orthodontic patients (age range, 12.7-18.2 years; mean, 14.3 years). A light buccally directed orthodontic force of 25 g was applied to the experimental tooth on 1 side, and a heavy orthodontic force of 225 g was applied on the contralateral premolar. After 12 weeks of force application, the experimental teeth were extracted and scanned with the microcomputed tomography x-ray system. Resorption craters were analyzed with specially designed software for direct volumetric measurements. The tooth movements produced by light and heavy forces were also measured. RESULTS: There was individual variation in all comparisons. The light force produced significantly less root resorption than did the heavy force. The maxillary first premolars were more likely to suffer from orthodontically induced inflammatory root resorption than the mandibular first premolars (P = 0.036). There was a significant difference between buccal and lingual surfaces (P = 0.003), with greater root resorption on the buccal surface. The distribution pattern of the resorption cavities was greatest in the buccal-cervical, buccal-middle, lingual-middle, and lingual-apical areas in both the light-force and heavy-force groups, corresponding with the pressure zones of tipping movement. The mean amount of tooth movement in the heavy-force group was almost twice as much as in the light-force group. CONCLUSIONS: The volume of root resorption craters induced by buccally directed forces for 12 weeks on the maxillary and mandibular first premolars was directly proportional to the magnitude of the force. The maxillary premolars seemed to be more susceptible to orthodontic root resorption than did the mandibular premolars.

Physical properties of root cementum: Part 13. Repair of root resorption 4 and 8 weeks after the application of continuous light and heavy forces for 4 weeks: a microcomputed-tomography study.

INTRODUCTION: The reparative process of root absorption begins in the periodontium when orthodontic force is discontinued or reduced below a certain level. Our aim was to evaluate cementum repair at 4 and 8 weeks of retention after 4 weeks of continuous light and heavy orthodontic forces. The effects of age, tooth movement, and fluoride exposure were also investigated. METHODS: Forty patients were recruited and divided into 4 groups of 10. The maxillary first premolars were loaded with either light (25 g) or heavy (225 g) orthodontic force. After 4 weeks of loading, the maxillary left first premolars were extracted as the positive control group, and the maxillary right first premolars were placed in retention for 4 or 8 more weeks before extraction; these were the experimental groups. The extracted teeth were studied with microcomputed tomography. To assess cementum repair, volumetric changes of the resorption craters were measured with specially designed computer software. Tooth movement was also measured on study casts taken before and after the extractions. RESULTS: Root resorption continued for 4 weeks after orthodontic force ceased. The resorptive activity was more pronounced from heavy forces. Passive retention after 4 weeks of light force had the least root resorption crater volume (cube root scale). The total amount of the cementum repaired did not depend on magnitude of orthodontic force or retention time within our parameters (P >0.05). This might indicate concurrence of resorption and repair during passive retention. Most repair seemed to occur after 4 weeks of passive retention following the 4 weeks of heavy forces. The volume of root resorption craters positively depended on tooth movement (P = 0.02) and negatively correlated with chronologic age (P <0.01). CONCLUSIONS: Although there was no significant difference in the amounts of repair between groups, root resorption continued for 4 weeks after orthodontic force stopped. Resorptive activity was more pronounced after the heavy forces. The reparative processes were different between the light and heavy forces, with marked individual variations. Repair seemed to become steady after 4 weeks of passive retention following 4 weeks of light force application, whereas most repair occurred after 4 weeks of passive retention following 4 weeks of heavy force application. Root resorption crater volume positively depended on tooth movement and negatively correlated with chronologic age.

Effect of low magnitude and high frequency mechanical stimuli on defects healing in cranial bones.

PURPOSE: The aim of this investigation was to assess the effect of low magnitude high frequency (LMHF) mechanical vibrated stimulation on healing the defects surgically imposed on craniofacial bones. MATERIALS AND METHODS: Forty 12-week-old C3H strain mice were separated into surgical and non-surgical groups. The surgical groups had a reproducible surgical bony lesion prepared in their right parietal bone. Both groups were further subdivided into vibration (experimental) and non-vibration (control) groups at 3 time points (zero hours, 2 weeks, and 4 weeks). The vibration groups were subjected to LMHF mechanical stimuli (30 Hz with peak strain 5 microepsilon) via a vibration machine for 20 minutes a day for 5 days a week for a total of 28 days. The specimens were analyzed using micro-computer tomography (micro-CT). RESULTS: Micro-CT volumetric measurement showed that in the surgical defects groups there was a significant decrease in the volume of the healing lesion with time (P < .001) and the linear decrease was significantly more pronounced in the vibration-treated group than the nontreated group (P < .001). Micro-CT histomorphometric measurement showed that in the nonsurgical groups there was no significant difference in microstructures of bony trabeculae between vibration-treated and nontreated groups. CONCLUSION: It is suggested that the introduction of LMHF mechanical stimuli in a healing bony lesion in the non-weight bearing bone significantly increases its healing capacity.

Physical properties of root cementum: Part 10. Comparison of the effects of invisible removable thermoplastic appliances with light and heavy orthodontic forces on premolar cementum. A microcomputed-tomography study.

INTRODUCTION: Orthodontic treatment with clear sequential removable thermoplastic appliances (TAs) is gaining popularity as an alternative to treatment with fixed appliances. The amount of orthodontically induced inflammatory root resorption generated by such appliances has not been investigated. In this prospective randomized clinical trial, we used x-ray microtomography to quantify resorption generated by treatment with ClearSmile appliances (ClearSmile, Woollongong, Australia) and compared the effects with those of heavy and light conventional orthodontic forces and no force. METHODS: The sample consisted of 54 maxillary first premolars in 27 patients who required bilateral extractions as part of their planned orthodontic treatment. The subjects were randomly assigned to 3 groups, each with 9 subjects. A split-mouth design was used, and forces were applied to the first premolars. In group 1, TAs were used to move teeth on 1 side in a buccal direction at a rate of 0.5 mm every 2 weeks (TA movement); the contralateral teeth were not moved and served at controls. In group 2, TA movement was used on 1 side. A buccal force of 225 g from a beta-titanium alloy cantilever spring (heavy force) was used on the contralateral side. In group 3, TA movement was used on 1 side. A buccal force of 25 g from a cantilever spring (light force) was used on the contralateral side. The treatment duration was 8 weeks (56 days +/- 1 day). The TAs were changed every 14 days, and each patient used 4 appliances. The springs were not reactivated. At the end of the study period, the teeth were extracted according to a strict protocol to prevent root damage. Resorption was measured with an x-ray microtomograph (1072, SkyScan, Aartselaar, Belgium). Software analysis determined quantity, location, and distribution of root resorption craters. RESULTS: The control teeth had the least amount of resorption. The light-force teeth had approximately 5 times more resorption than the control teeth (P <.001). The TA teeth had similar but slightly greater resorption than the light-force teeth, or approximately 6 times greater than the control teeth (P <.001). The heavy-force teeth had the most resporption, about 9 times greater than the controls (P <.001). CONCLUSIONS: Clear removable TAs have similar effects on root cementum as light (25 g) orthodontic forces with fixed appliances.

Characterisation of the macroporosity of polycaprolactone-based biocomposites and release kinetics for drug delivery.

Microporous, biocomposite matrices comprising a continuous phase of poly(epsilon-caprolactone) (PCL) and a dispersed phase of lactose or gelatin particles with defined size range (45-90, 90-125 and 125-250 microm) were produced by precipitation casting from solutions of PCL in acetone. Scanning electron microscopy (SEM) analysis revealed a characteristic surface morphology of particulates interspersed amongst crystalline lamellae of the polymer phase. Rapid release of around 80% of the lactose content occurred in PBS at 37 degrees C in 3 days, whereas biocomposites containing gelatin particles of size range 90-125 and 125-250 microm, respectively, displayed gradual and highly efficient release of around 90% of the protein phase over 21 days. A highly porous structure was obtained on extraction of the water-soluble phase. Micro-computed tomography (Micro-CT) and image analysis enabled 3-D visualisation and quantification of the internal pore size distribution. A maximum fractional pore area of 10.5% was estimated for gelatin-loaded matrices. Micro-CT analysis confirmed the presence of an extensive system of macropores, sufficiently connected to permit protein diffusion, but an absence of high volume, inter-pore channels. Thus tissue integration would be confined to the matrix surface initially if the designs investigated were used as tissue-engineering scaffolds, with the core potentially providing a depot system for controlled delivery of growth factors.

Attachment of the utricular and saccular maculae to the temporal bone.

The present investigation concerns the true morphology of the attachment of the two otolith receptor organs the utricular and the saccular maculae in two and three dimensions. By applying a new visualization method, which utilized the application of X-ray microtomography and a method of contrast enhancement based on en-bloc staining in osmium tetroxide, we were able to overcome problems of artefact production such as tissue distortion and loss of valuable information that was present in previous studies. A series of more than 1000 axial sections were obtained for each of the specimens, which subsequently formed the basis for detailed 2D and 3D visualizations. Our interpretations of these data reveal that the saccular maculae are closely attached to the curved bony surface of the temporal bone as traditionally believed, but the utricular macula is attached to the temporal bone only at the anterior region of the macula.

Application of invariant grey scale features for analysis of porous minerals.

Three-dimensional (3D) texture analysis can be used to differentiate similar materials which have a complex structural nature that is not easily reduced to geometric primitives. A method which extends the concept of invariant grey scale features to non-structured 3D textures is introduced and applied to the study of five processed mineral carbon materials which are characteristically similar but derive from different industrial sources. X-ray microtomography (XRMT) was used to obtain 3D tomographic data with isotropic voxel spacing of 9.8 microm. These data were used to construct invariant features for 3D texture measurement via Monte Carlo based sampling routines and integrals of grey scale relational kernel functions. The procedure produced multi-component texture vectors, which were successfully tested against texture samples as a classification-recognition tool. Identification accuracies ranging from 69% to approximately 84% were achieved for the five material sources examined. This result provides a sound basis for quantitative analysis of these materials which to date have proved very difficult to examine using traditional image analysis tools because of their complex natural structure.

Characterisation of enamel white spot lesions using X-ray micro-tomography.

OBJECTIVES: The aim of this study was to characterise the mineral density (MD) of natural enamel white spot lesions (WSLs) using X-ray micro-tomography calibrated with different density hydroxyapatite phantoms. METHODS: Seven natural WSLs from four extracted non-carious premolar teeth were scanned at a voxel size of 7.6 microm using a desktop X-ray micro-tomography system. Five hydroxyapatite phantoms (sintered pellets of hydroxyapatite powder) with densities ranging from 1.52 to 3.14 g/cm(3) were used as calibration standards for each scan. Three-dimensional image reconstruction enabled MD gradients throughout the lesion to be quantified using an MD calibration equation derived from hydroxyapatite phantoms. Background noise generated during the measurement of MD was reduced using a Gaussian filter. RESULTS: Gaussian filter reduced the signal-to-noise ratio (standard deviation) significantly while the basic MD information (average value) remained intact. The mineral gradients through the WSLs examined were compared and are discussed in terms of existing literature. The MD of sound enamel, apparent intact surface layer of WSL, and lowest level of WSL was found to be 2.65-2.89 g/cm(3), 2.23-2.58 g/cm(3) and 1.48-2.03 g/cm(3), respectively. Our MD results are comparable with other studies. CONCLUSIONS: X-ray micro-tomography is a sensitive in vitro technique capable of characterising and quantifying MD of small non-cavitated WSLs. This method has a promising potential for future carious and quantitative remineralisation studies.

A new approach to visualizing the membranous structures of the inner ear - high resolution X-ray micro-tomography.

CONCLUSION: Through the application of high resolution X-ray micro-tomography and a method of contrast enhancement based on en bloc staining in osmium tetroxide (OsO4), we report an approach that facilitates accurate three-dimensional (3D) reconstruction to reveal the fine structure of the inner ear. OBJECTIVES: To overcome the problems of artefacts, including tissue distortion and loss of 3D context that are inherent in existing methods that rely on manual dissection and/or histological sectioning. MATERIALS AND METHODS: A staining protocol was developed that involved the en bloc application of the OsO4 solution (2% w/v) for an extended period of time. The samples were then scanned using an X-ray micro-tomography platform and subsequent 3D visualizations were constructed. RESULTS: The digital nature of the data allowed a complete 3D contextual visualization to be constructed whereby the individual sensory structures could be seen in relation to other inner ear structures. This included a detailed anatomy of the membranous labyrinth and nerve supply including the spatial configuration of the utricular and saccular maculae. This is a new way of undertaking temporal bone histology.

Physical properties of root cementum: part 8. Volumetric analysis of root resorption craters after application of controlled intrusive light and heavy orthodontic forces: a microcomputed tomography scan study.

INTRODUCTION: Intrusion is a critical type of orthodontic tooth movement in relation to external root resorption. Our aims in this prospective randomized clinical trial were to quantify, 3 dimensionally, the amount of root resorption when controlled light and heavy intrusive forces were applied to human premolars and to establish the sites where root resorption is more prevalent. METHODS: Fifty-four maxillary first premolars, orthodontically indicated for extraction from 27 patients (left and right maxillary first premolars from each), were intruded for 28 days with buccal and palatal beta-titanium-molybdenum alloy 0.017 x 0.025-in cantilever springs. The patients were randomly divided into 3 groups, and various levels of force were used: group 1, heavy force (225 g) on 1 side and control force (0 g) on the contralateral side; group 2, light force (25 g) on 1 side and control force (0 g) on the contralateral side; group 3, light force (25 g) on 1 side and heavy force (225 g) on the contralateral side. After the experimental period, the teeth were extracted under a strict protocol to prevent root surface damage and analyzed by using a microcomputed tomography scan x-ray system (SkyScan-1072, Skyscan, Aartselaar, Belgium) and specially designed software for direct volumetric measurements. RESULTS: The volume of the root resorption craters after intrusion was found to be directly proportional to the magnitude of the intrusive force applied. The results showed that the control group had fewer and smaller root resorption craters, the light force group had more and larger root resorption craters than the control group, and the heavy force group had the most and the largest root resorption craters of all groups. A trend of linear increase in the volume of the root resorption craters was observed from control to light to heavy groups, and these differences were statistically significant. The mean volumes of the resorption craters in the light and heavy force groups were 2 and 4 times greater than in the control groups, respectively. The mesial and distal surfaces had the greatest resorption volume, with no statistically significant difference between the 2 surfaces.