Biomedical subjects

Sergio Caputi

Publications and source records attributed to Sergio Caputi.

At least 19 recordsLinked to original sources

PubMed2006

A preliminary study of healing of diode laser versus scalpel incisions in rat oral tissue: a comparison of clinical, histological, and immunohistochemical results.

OBJECTIVE: The aim of this preliminary study was to compare wound healing of rat oral tissues after surgical procedure with diode laser or scalpel. Healing was evaluated histologically, immunohistochemically, and by measurement of 2 nitric oxide synthase isoforms (eNOS and iNOS) as intracellular messenger molecules with important immune functions. The instruments were also evaluated for performance and ease of use. STUDY DESIGN: Twenty-four standardized incisions were performed in the hard palate of 12 male Wistar rats. Each rat received 2 incisions on the opposite sides of the palate by using a steel scalpel (control group) and a diode laser (808 nm) at a power output of 4 W and 6 W (test group). Histological and immunohistochemical analyses were performed on tissue samples after 7 and 14 days. The expression of eNOS and iNOS was confirmed by RT-PCR (reverse transcriptase-polymerase chain reaction) and Western blot analysis. RESULTS: Scalpel repair was found to be equivalent to or better than laser repair at the intervals measured. Histological analysis showed that incision wound repair after laser surgical procedure was related to parameters and beam characteristics. Diode laser at a power output of 6 W showed the worst results of tissue repair, especially after 7 days. On the contrary, the extent of epithelial damage lateral to the wound edge and the extent of collagen denaturation were near equal with scalpel incision and laser irradiation at 4 W after 14 days. Biochemical analysis of RT-PCR and Western blots also confirmed histological results with a greater concentration of eNOS and iNOS after 7 days of laser surgical procedure. CONCLUSIONS: Clinical and histological findings change over time for different treatments. Diode laser tends to produce more pronounced changes than conventional scalpel surgical procedure (due to tissue thermal damage), with corresponding greater inflammatory reaction and delay in tissue organization only at the initial stage. Thus, long-term histology is critical for predicting treatment results. The clinical use of low-level diode laser for tissue welding of oral mucosa should be investigated further, since it appears to be a good alternative to scalpel incision and suture repair.

Animals↗

PubMed2006

Evaluation of cervical posture following palatal expansion: a 12-month follow-up controlled study.

This study evaluated the effects of rapid palatal expansion (RPE) on nasopharyngeal airway size, head posture, and cervical curvature angle in children with nasal obstruction. The patients were 45 female subjects (8-15 years of age) who had a reduced nasopharyngeal airway size and were subjectively assessed as being mouth breathers and requiring palatal expansion. They were randomly allocated to one of two groups: 23 subjects in the first group were treated with RPE, while the 22 subjects in the other group were monitored for approximately 14 months prior to commencing therapy, and became untreated controls. Lateral skull radiographs, taken in the natural head position, were obtained at the first visit (T0) and 6 (T1) and 12 (T2) months later for all subjects. The differences between the cephalometric variables at baseline and after 6 and 12 months were evaluated with a one-way repeated measures analysis of variance. Where significant interactions were found, a Bonferroni corrected paired Student's t-test was performed for pairwise comparisons. Changes in cephalometric variables within the experimental groups were tested by paired Student's t-tests as a post hoc procedure. Finally, a correlation matrix, using the Pearson correlation coefficient, was computed in order to evaluate the relationship between the change in airway adequacy and (1) the amount of maxillary expansion, (2) chronological age, (3) the amount of time that the appliance was activated, and (4) morphological and postural measurements of the face. At T1, children under active treatment showed a statistically significant increase in nasopharyngeal airway size, cervical curvature angle, and flexion of the head, together with a significant decrease in craniocervical angulation (all P < 0.05). These changes were all found to be stable at T2. No significant changes were seen in the control group. The correlation coefficients indicated a significant correlation between nasopharyngeal airway size and craniocervical angulation (SN/OPT angle; r = -0.61, P < 0.05). The findings indicate that RPE is capable of increasing nasopharyngeal airway size in young females, which results in a decrease in craniocervical angulation. Clinically, the findings seem to suggest that improvement of respiratory function could result in a change in head posture.

Adolescent↗

PubMed2006

Bone microvascular pattern around loaded dental implants in a canine model.

The vascularity of the implant bed is a very important parameter in both bone formation and maintenance after dental implants insertion. The relationship between bone and vessels network organization is still unknown. The aim of this study was to investigate the three-dimensional bone vascular canals of the peri-implant bone after loading. A total of ten implants with sandblasted and acid-etched surface were placed in the mandible of a beagle dog. Three months later, the implants were connected and loaded. The dog was killed after 12 months. The specimens were embedded and processed for scanning electron microscopy (SEM) analysis. After a 1-year loading period, a very intricate vessel network could be seen around the implants. The vessels, with neighbouring soft tissues, were round in shape and showed a lot of anastomoses with a mesh-like appearance. They ran circularly around the dental implant. In the bone, the majority of the vessels appeared to ran parallel to the mandibular canal. After a 1-year loading period, the peri-implant bone vasculature looked like a mesh that surrounded the implants. Nevertheless, the presence of many thick vessels inside the peri-implant crestal bone indicates a high metabolic need and also a different bone organization, as no osteons were noted. The crater-like bone loss around the marginal part of the implant could be related to the microvasculature "strain". A high strain level could continuously activate the osteocyte-vessel syncytium, producing a net bone loss.

Alveolar Bone Loss↗

PubMed2006

Fracture resistance of implant-supported screw- versus cement-retained porcelain fused to metal single crowns: SEM fractographic analysis.

OBJECTIVES: The present in vitro study aimed at evaluating the fracture resistance of both implant-supported screw- and cement-retained porcelain fused to metal (PFM) single crowns. A scanning electron microscope (SEM) evaluation of the mode of failure of the specimens was also performed. METHODS: Forty PFM premolar-shaped identical single crowns were realized. The restorations were divided into two groups: cement-retained (group 1) and screw-retained (group 2) prostheses. Compressive loading tests and SEM fractographic analyses were performed. The data were statistically analysed by means of the Student's t-test, with a confidence interval of 95%. RESULTS: The mean fracture load value was 1657 (+/-725) N in group 1 and 1281 (+/-747) N in group 2; the statistical analysis pointed out no significant differences between the two groups (p=0.115). The mean work at maximum load value was 0.775 (+/-0.619) J in group 1 and 0.605 (+/-0.526) J in group 2; the statistical analysis pointed out no significant differences between the two groups (p=0.355). All the samples were affected by cohesive fractures of the porcelain. Screw-retained crowns showed microcracks at the level of the occlusal access to the screw and extensive fractures in the whole thickness of the ceramics. On the contrary, cement-retained restorations were affected by less wide paramarginal fractures of the porcelain. SIGNIFICANCE: A stronger implant-prosthetic connection was noticed in cemented restorations group than in screw-retained single crowns. Even though negatively influenced by the presence of the occlusal access to the screw, the metal-ceramics bond can be considered predictable in both the implant-prosthetic connection systems analysed.

Cementation↗

PubMed2006

Tissue healing under provisional restorations with ovate pontics: a pilot human histological study.

STATEMENT OF PROBLEM: Ovate pontics mimic the natural tooth contour and provide an esthetic result however, few studies have evaluated the histological changes in underlying tissues. PURPOSE: The purpose of this pilot study was to histologically evaluate the healing of gingival tissues in contact with provisional ovate pontics after 2 weeks. MATERIAL AND METHODS: Three patients requiring fixed partial dentures participated in this study. The provisional restorations consisted of a fixed partial denture having 2 ovate pontics: one in acrylic resin (Jet), with an ovate shell made of low-fusing ceramic (Duceram LFC); the other made completely of the same acrylic resin (control). After 2 weeks, biopsies of the gingival tissues beneath the pontics were retrieved for histological examination, and immunohistochemistry for evaluation of the vascular endothelial growth factor (VEGF) was performed. Data were analyzed using descriptive statistics. RESULTS: Clinically, all of the ovate pontic-prepared sites showed partial healing. Histologically, the thickness of the entire mucosa was similar in both specimens; however, in some regions, the epithelium presented ulcerations that were generally deeper and more frequent in control sites than in test sites. Immunohistochemical results showed that tissues beneath LFC pontics seemed to be less inflamed since they demonstrated a lower expression of VEGF (10.7 +/- .8) compared to those beneath acrylic resin ovate pontics (33.9 +/- 2.5). CONCLUSION: This pilot study demonstrated that the placement of provisional LFC ovate pontics may be advantageous for the reparative processes of the underlying tissues.

Acrylic Resins↗

PubMed2006

Collagen fiber orientation near a fractured dental implant after a 5-year loading period: case report.

PURPOSE: Fracture of an implant is one of the possible complications of dental implants. It is a quite rare event but of high clinical relevance. Nevertheless, it represents an important opportunity for evaluating the peri-implant bone-tissue response to implant overloading in human beings. The aim of the present study was a scanning electron microscopy evaluation of a screw-shaped implant retrieved because of fracture and a birefringence analysis of the tissue near the fractured implant. MATERIALS AND METHODS: There was 1 fractured screw-shaped implant retrieved from a patient with a trephine bur, and it was processed for histology. The specimen was analyzed under both scanning electron microscopy and circularly polarized light microscopy. RESULTS: The scanning electron microscopy fractography analysis showed the typical signs of a fatigue-fracture, with large plastic deformations on the implant. The fracture seemed to start from the internal coil of the implant. Under circularly polarized light microscopy investigation, a bone-implant contact percentage of 81.6% +/- 1.5% (mean +/- standard deviation) was found. The amount of the transverse collagen fibers was of 68.3%, and the amount of the longitudinal collagen fibers was of 31.7%. The difference was statistically significant for z = 2.247 (P = 0.025). CONCLUSION: The fracture of the implant was most probably correlated to a fatigue of the material mainly associated to a lesion of the internal coil. The high level of bone-implant contact percentage was correlated to a predominant transverse collagen fiber orientation of the collagen fibers in the peri-implant bone.

Bone Remodeling↗

PubMed2006

Maxillary sinus augmentation with different biomaterials: a comparative histologic and histomorphometric study in man.

OBJECTIVE: Rehabilitation of the edentulous posterior maxilla with dental implants can be difficult because of insufficient bone volume caused by pneumatization of the maxillary sinus and crestal bone resorption. Different biomaterials have been used for sinus augmentation. The aim of the study was to compare different materials in maxillary sinus augmentation in man. METHODS: A total of 94 patients participated in this study. Inclusion criteria were maxillary partial (unilateral or bilateral) edentulism involving the premolar/molar areas, and the presence of 3-5-mm crestal bone between the sinus floor and alveolar ridge. A total of 362 implants were inserted. There were 9 biomaterials used in the sinus augmentation procedures. Each patient underwent 1 biopsy after 6 months. A total of 144 specimens were retrieved. RESULTS: None of the 94 patients had complications. All implants were stable, and x-ray examination showed dense bone around the implants. Mean follow-up was 4 years. There were 7 implants that failed. Histologic resultsshowed that almost all the particles of the different biomaterials (i.e., autologous bone, demineralized freeze-dried bone allograft Biocoral [Inoteb, St. Gonnery, France], Bioglass [US Biomaterials, Alachua, FL], Fisiograft [Ghimas, Bologna, Italy], PepGen P-15 [Dentsply Friadent CeraMed, Lakewood, CO], calcium sulfate, Bio-Oss [Geistlich Pharma AG, Wohlhusen, Switzerland], and hydroxyapatite) were surrounded by bone. Some biomaterials were more resorbable than others. Included are the histomorphometry clarified features of the newly formed bone around the different grafted particles. CONCLUSION: All biomaterials examined resulted in being biocompatible and seemed to improve new bone formation in maxillary sinus lift. No signs of inflammation were present. The data are very encouraging because of the high number of successfully treated patients and the good quality of bone found in the retrieved specimens.

Aged↗

PubMed2006

Intra-articular and muscle symptoms and subjective relief during TMJ internal derangement treatment with maxillary anterior repositioning splint or SVED and MORA splints: A comparison with untreated control subjects.

Discomfort associated with wearing an intraoral splint represents a problem in the management of temporomandibular joint (TMJ) internal derangement. This study evaluated whether the use of a mandibular splint during the day and a maxillary splint at night could be more comfortable and therefore as efficacious in internal derangement treatment as a maxillary splint (AR splint). Fifty (50) patients (average age 28.8; range 14-63) with confirmed internal derangement in at least one TMJ were divided into three groups: 20 patients treated with AR splint (Group I); 20 patients treated with a SVED (Sagittal Vertical Extrusion Device) and a MORA (Mandibular Anterior Repositioning Splint) (Group II); and 10 patients who underwent no treatment (Control Group). Joint noise, pain intensity and its character (as constant or chewing/biting pain), muscular pain, and subjective relief were evaluated monthly before treatment began (T0) and for six months thereafter. The following results were found: 1. Subjects in Group I and Group II displayed a significant decrease in joint pain (p<0.001), constant pain (p<0.001), chewing/biting pain (p<0.001), joint noise and muscle pain from the beginning through the sixth month follow-ups; 2. At T1 and T2, subjects in Group II reported significantly lower discomfort associated with the devices than subjects in Group I. The use of two splints seems to be as efficacious as the use of an AR maxillary splint; however an AR splint is considered more comfortable by patients, especially during the first months of therapy.

Adolescent↗

PubMed2006

Histologic and ultrastructural analysis of regenerated bone in maxillary sinus augmentation using a porcine bone-derived biomaterial.

BACKGROUND: The purpose of the present study was the histologic and ultrastructural evaluation of a biomaterial composed of cortical pig bone in the form of granules. METHODS: After maxillary sinus augmentation using this biomaterial, 10 specimens were retrieved after 5 months in 10 patients using this biomaterial. The specimens were processed to be observed under light microscopy (LM) and transmission electron microscopy (TEM). Histomorphometric measurements were presented by means +/- standard deviations. RESULTS: LM showed that most of the particles were surrounded by newly formed bone. In some areas, the osteoid matrix was present; however, mainly compact bone was present at the interface. There was no evidence of an acute inflammatory infiltrate. The newly formed bone was 36% +/- 2.8% and marrow spaces were 38% +/- 1.6%, whereas residual grafted material was 31% +/- 1.6%. Under TEM, all phases of bone formation (osteoid matrix, woven, and lamellar bone) were observed in proximity with the biomaterial particles. The bone-biomaterial interface showed a close contact between the porcine bone particles and the surrounding bone that had mainly features of mature bone with numerous osteocytes. A lamina limitans was sometimes present at this interface. CONCLUSIONS: According to our knowledge, this is the first study presenting data on TEM of a porcine bone-derived biomaterial used in sinus augmentation procedures in humans. Our findings show that this is a biocompatible biomaterial that can be used for maxillary sinus augmentation procedures without interfering with the normal reparative bone processes.

Absorbable Implants↗

PubMed2005

Collagen fiber orientation near dental implants in human bone: do their organization reflect differences in loading?

This study is the first to investigate the collagen fiber orientation in human bone around titanium dental implants after loading. Birefringence under circularly polarized light (CPL) and scanning electron microscopy (SEM) investigation were used to assess both collagen orientation and density. Twenty osseointegrated dental implants were retrieved from the mandible bone of 10 patients and were used in the present study. The implants were retrieved after 6 months of function. The birefringence measurements were performed on digitized images using both the peri-implant bone (PB) and the alveolar bone (AB) retrieved at the moment of implant placing. All images detected at 100x were measured using a software image analysis. The results showed that 32.96% (3.208 +/- 0.435 mm(2)) of the PB area was composed of transverse collagen fibers while only 19.70% (1.957 +/- 0.253 mm(2)) was composed of longitudinally collagen fibers. In the AB 26.99% (2.620 +/- 0.520 mm(2)) of the examined area was composed of transverse collagen fibers while 22.25% (2.160 +/- 0.320 mm(2)) was composed of longitudinally collagen fibers. The CPL measurements of the birefringence indicated that the difference in area between the two collagen fibers orientations was statistically significant (p = 0.03) for both AB and PB. In PB the transverse collagen fibers were significantly increased (p < 0.01) than in AB; also the longitudinal collagen fibers differ significantly in the two groups (p = 0.02). The transverse collagen fibers in PB are more present under the lower flank of the threads where the load acts with a compression vectors, while outside the tip of the implant threads the collagen fibers run more longitudinally due to the loads that act with a tensile vectors. SEM observations showed, in the first collagen layers facing the implant surface, a random direction of the collagen fibers, while in the areas away from the implant surface the collagen fibers were well oriented and run parallel. In conclusion, in these loaded dental implants, the bone adjacent to the first two implant threads shows a significant increase of the amount of transverse collagen fibers that were mainly associated with the lower flank of the threads where compressive load acts. The longitudinal collagen fibers also differs significantly from those found in the AB.

Adult↗

PubMed2005

Quantitative evaluation of the fibrin clot extension on different implant surfaces: an in vitro study.

The aim of the present study was a quantitative evaluation of the in vitro fibrin clot extension on different implant surfaces. Forty-five disk-shaped commercially pure Grade 2 titanium samples with three different surface topographies (machined, DPS, and Plus) were used in the present study. For the quantitative evaluation of the fibrin clot, 30 specimens were used (10 per group); human whole blood was employed. Venous blood was drawn from three healthy adult volunteers, and 0.2 mL were immediately dropped onto the surface of each specimen. Contact time was 5 min at room temperature; then the samples were rinsed with saline solution and fixed in a buffered solution of glutaraldehyde and paraformaldehyde. Samples were washed again with buffer and dehydrated in an ascending alcohol series. Specimens belonging to all groups were observed under SEM at a magnification of 1000x. From each sample, 50 random micrographs were collected in .tif format with an N x M 1024 x 768 grid of pixels. Quantitative analysis of fibrin clot extension showed the following results: in machined samples fibrin clot extension was 345987.2 +/- 63747.7 pixels(2) (mean +/- SD), in DPS samples fibrin clot extension was 375930.9 +/- 54726.86 pixels(2) (mean +/- SD), and in Plus samples, fibrin clot extension was 612333.6 +/- 46268.42 pixels(2) (mean +/- SD). With ANOVA it was possible to find that there were significant differences among the groups. The Tukey test revealed that the extension of the fibrin clot of Plus samples was statistically higher compared to both machined and DPS samples. The results of this in vitro study indicate that there is a correlation between implant surface morphology and fibrin clot extension. Improvement in surface microtexture complexity seems to determine the formation of a more extensive and three dimensionally complex fibrin scaffold. Further investigations are necessary to explain in more detail the mechanisms that regulate the fibrin clot formation on different implant surfaces.

Adsorption↗

PubMed2005

Friction of conventional and self-ligating brackets using a 10 bracket model.

The friction generated by various bracket-archwire combinations previously has been studied using in vitro testing models that included only one or three brackets. This study was performed using a specially designed apparatus that included 10 aligned brackets to compare the frictional resistance generated by conventional stainless steel brackets, self-ligating Damon SL II brackets and Time Plus brackets coupled with stainless steel, nickel-titanium and beta-titanium archwires. All brackets had a 0.022-inch slot, and five different sizes of orthodontic wire alloys used. Each bracket-archwire combination was tested 10 times, and each test was performed with a new bracket-wire sample. Time Plus self-ligating brackets generated significantly lower friction than both the Damon SL II self-ligating brackets and Victory brackets. However, the analysis of the various bracket-archwire combinations showed that Damon SL II brackets generated significantly lower friction than the other brackets when tested with round wires and significantly higher friction than Time Plus when tested with rectangular archwires. Beta-titanium archwires generated higher frictional resistances than the other archwires. All brackets showed higher frictional forces as the wire size increased. These findings suggest that the use of an in vitro testing model that includes 10 brackets can give additional interesting information about the frictional force of the various bracket-archwires combinations to the clinician and the research worker.

Biomechanical Phenomena↗

PubMed2005

A new one-step dental flowable composite for orthodontic use: an in vitro bond strength study.

A new flowable composite, Denfil Flow, has shown an acceptable shear bond strength for bonding orthodontic brackets, when used with an intermediate, unfilled, low-viscosity resin. According to the manufacturer, it also shows a good viscosity for use with no preliminary adhesive. This could reduce the total time of bonding procedure while maintaining clinically useful bond strength. The aim of the current research was to assess this property. Eighty extracted human premolars were randomly divided into four equal groups. Stainless steel brackets were bonded to etched enamel using (1) Denfil Flow, (2) a traditional flowable composite (Dyract Flow), (3) Denfil Flow composite resin and an intermediate liquid resin, and (4) Transbond XT adhesive. Debonding was performed with a shearing force. The residual adhesive on the enamel surface was evaluated using the adhesive remnant index. The bond strength of Denfil Flow (34.8 MPa) showed no significant difference with the other control groups and was clinically acceptable. Denfil Flow and Dyract Flow tended to display cohesive failure within the adhesive. Denfil Flow can be used without liquid resin to reduce the bonding procedure time while maintaining acceptable bond strength. Further studies are required to evaluate the enamel surface of the teeth after the same polishing procedure in the four groups.

Analysis of Variance↗

PubMed2005

Genetic profiling of central giant cell granuloma of the jaws.

Central giant cell granuloma (CGCG) of the jaws is a central osteolytic lesion characterized histologically by multinucleated giant cells in a background of ovoid to spindle-shaped mesenchymal cells. Whether CGCG is a reactive lesion or a truly benign neoplasm remains undetermined, and the mechanism determining the onset of the disease remains unknown. To have more information regarding the genetic events involved in CGCG, the authors decided to perform an expression profile. Samples were derived from two surgically resected CGCG of the mandible. RNA extracted from a pool of three normal bone tissues was used as control. By using DNA microarrays containing 19,200 genes, the authors identified several genes whose expression was significantly up- or down-regulated. The differentially expressed genes cover a broad range of functional activities: cell cycle regulation; signal transduction; and vesicular transport. It was also possible to detect some genes whose function is unknown. The authors believe the data reported to be the first genetic portrait of CGCG of the jaws. Several markers have been identified that can potentially help in identifying some biological behavior (ie, quiescent versus aggressive lesions), as well as genes whose products could be potentially disease-specific targets for therapy. However, the authors think that more cases are needed, especially those comparing quiescent and aggressive lesions, before the exact profile of CGCG is known.

Gene Expression↗

PubMed2005

Melatonin provokes cell death in human B-lymphoma cells by mitochondrial-dependent apoptotic pathway activation.

Apoptosis is an important cell suicide programme involved in physiological and pathological processes. Apoptosis can be induced in different ways depending on cell type and acquired signal. Melatonin, the major secretory product of the pineal gland, participates in many important physiological functions and displays a remarkable functional versatility exhibiting antioxidant, oncostatic, anti-aging, and immunomodulatory properties. Recently, it has been shown that, in addition to pineal gland, human lymphoid cells are an important physiological source of melatonin and that may be involved in the regulation of the immune system. In this work, we examine the effect of melatonin on RAMOS-1 human leukaemic cells. Cell growth and viability, DNA fragmentation and JC-1, and annexin V expression have been determined. To elucidate the mechanism of action of melatonin, Western blot analyses for Bcl-2 and caspase-3 expression, and cytochrome c release were carried out. The results suggest that the apoptotic effect of melatonin is associated with cell-cycle arrest, downregulation of Bcl-2, mitochondrial membrane depolarization, cytochrome c release and activation of caspase-3. The intrinsic (mitochondrial dependent) pathway of caspase activation is the 'point of no return' commitment to cell death. Taken together, our study indicates that melatonin may play a role as potential therapeutic drug in specific lymphoproliferative diseases.

Annexin A5↗

PubMed2005

Evaluation of cervical posture of children in skeletal class I, II, and III.

Previous studies on the relationship between morphological structure of the face and cervical posture have predominantly focused on vertical dimensions of the face. The aim of this study was to investigate whether there are significant differences in cervical posture in subjects with a different sagittal morphology of the face, i.e., a different skeletal class. One hundred twenty (120) children (60 males and 60 females, average age 9.5 yrs., SD+/-0.5) were admitted for orthodontic treatment. Selection criteria was: European ethnic origin, date of birth, considerable skeletal growth potential remaining and an absence of temporomandibular joint dysfunction (TMD). Lateral skull radiographs were taken in mirror position. Subjects were divided into three groups based on their skeletal class. The cephalometric tracings included postural variables. The most interesting findings were: 1. children in skeletal class III showed a significantly lower cervical lordosis angle (p<0.001) than the children in skeletal class I and skeletal class II; 2. children in skeletal class II showed a significantly higher extension of the head upon the spinal column compared to children in skeletal class I and skeletal class III (p<0.001 and p<0.01, respectively). This is probably because the lower part of their spinal column was straighter than those of subjects in skeletal class I and II (p<0.01 and p<0.001, respectively). Significant differences among the three groups were also observed in the inclination of maxillary and mandibular bases to the spinal column. The posture of the neck seems to be strongly associated with the sagittal as well as the vertical structure of the face.

Axis, Cervical Vertebra↗

PubMed2005

Collagen fiber orientation in human peri-implant bone around immediately loaded and unloaded titanium dental implants.

BACKGROUND: The main factor in determining the mechanical properties of bone is the collagen configuration. METHODS: This study investigated the birefringence in human bone around loaded and unloaded titanium dental implants to evaluate the collagen fiber orientation using circularly polarized light (CPL) and scanning electron microscopy (SEM). A total of 10 titanium dental implants, five immediately loaded and five unloaded, were used. The birefringence measurements were performed on digitized images of both loaded and unloaded implants. All images detected at 50x were measured using a software image analysis. RESULTS: In the bone around loaded implants, the transverse collagen fiber area was 45,481+/-3,037 pixel2 (mean+/-SD), while the area of longitudinal collagen fibers was 13,676+/-2,232 pixel2 (mean+/-SD). In the unloaded implants, the transverse collagen fiber area was 32,174+/-2,554 pixel2 (mean+/-SD), while the area of longitudinal collagen fibers was 89,073+/-1,960 pixel2 (mean+/-SD). The CPL measurements of the birefringence for transverse collagen fibers of loaded versus unloaded implants indicated that the differences were statistically significant (P <0.05). The results for the longitudinal collagen fibers of loaded versus unloaded implants were also statistically significant (P <0.05). CONCLUSIONS: In the bone around loaded dental implants, transverse collagen fibers were more abundant, while in the unloaded implants, collagen fibers run more longitudinally. The load seemed to determine the collagen fiber orientation.

Biocompatible Materials↗

PubMed2005

Capacity of coronal dentin to increase fiberglass post retention: a pull-out test.

PURPOSE: To evaluate the capacity of residual dentin in the coronal part of the root canal to increase the retention of serrated fiberglass posts (Extra-glass P-6%). METHODS: 40 freshly-extracted maxillary central incisors were randomly and evenly divided into four test groups (TGs) with no (TG0), one (TG1), two (TG2) and three (TG3) coronal walls, respectively. After shaping, the canals were filled with gutta-percha and prepared to receive fiberglass posts. Coronal wall dentin was etched with 38% phosphoric acid for 60 seconds, rinsed, and dried. Dentin bonding agent (Prime & Bond NT) was applied, and fiberglass posts were luted for 8 mm into the post space using a self-cure composite (ResiLute). All samples were then subjected to tensile forces in a universal testing machine. Data were analyzed with ANOVA and Student t-tests (P< 0.01). RESULTS: The samples with residual coronal dentin showed higher bond strength than the samples without residual crown walls (TG0=100.30N; TG1=201.83N; TG2=263.54N; TG3=278.86N). The differences between the groups were all statistically significant at P< 0.01, except for the difference in tensile strength between TG2 and TG3, which was not statistically significant. Residual crown walls significantly increased the tensile load required to displace the posts.

Analysis of Variance↗