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Improvement of the implant-bone interface is still an open problem and the interest in chemical modification of implant surfaces for cementless fixation has grown steadily over the past decade. Mechanical and histomorphometric investigations were performed at different times on implants inserted into sheep femoral cortical bone to compare the in vivo osseointegration of titanium screws ( X 3.5 x 7 mm length) with different surface treatments. After 8 weeks of implantation, the push-out force of anodized and hydrothermally treated implants (ANODIC) was significantly higher than that of machined implants (MACH) (36%, p<0.0005), whereas a decrease of 39% was observed for acid-etched implants (HF) when compared to other surface treatments. After 12 weeks of implantation, the push-out force values of HF implants were still significantly lower than those observed for MACH (-19%, p<0.01) and hydroxyapatite vacuum plasma-sprayed implants (HAVPS, -25%, p<0.0005), and the highest push-out force was found in HAVPS (p<0.001) implants. After 8 and 12 weeks of implantation, the AI of HF implants was significantly (p<0.05) lower ( approximately -25%) than that of MACH, HAVPS and ANODIC implants. In conclusion, results appear to confirm that there are no specific differences between ANODIC and HAVPS implants in terms of behavior. Moreover, although MACH implants show some surface contaminating agents, they appear to ensure good osseointegration within 12 weeks both mechanically and histomorphometrically, as do ANODIC and HAVPS implants. However, further studies are required to investigate bone hardness and mineralization around implants.

Owing to their possible carcinogenic effect, asbestos and other silica derivatives have been identified as priority substances for risk reduction and prevention of pollution. Neutralisation procedures have thus become a topical research subject in many European and American countries. In the present study, silica derivatives (asbestos-containing and asbestos substitutes like slag wool, rock wool, cement asbestos) were fully impregnated with an epoxy resin according to the procedure used for the in situ impregnation with viscous polymeric media, which penetrate and cement the fibres in place and reduce the risk of their dispersion in air. Untreated and treated samples were used to investigate their in vitro interaction with a human continuous epithelial cell line (NCTC 2544 keratinocytes) and test the resin's efficiency in passivating the surface activity of the fibrous particulate. SEM and morpho-quantitative data evidenced that impregnation with the epoxy resin modifies the mineral fibres' bioactivity (reduction of cell adhesion and decreased spread/round cell ratio) and demonstrated the value of in vitro cell testing after passivation as a risk-assessment procedure. These tests could be used for the rapid determination of the level of passivation of new synthetic mineral fibrous materials subjected to resin impregnation.

The periodontal ligament (PDL) has been found to house progenitor elements which may give rise to a new periodontium when properly triggered. Complex molecular mechanisms are involved in guiding such cells towards their final regenerative task. Hyaluronan (HA), an extracellular matrix molecule abundantly present during early tissue development, is usually found at high concentrations in all adult mammalian PDL tissue. In this study, PDL cells were cultured on HA coated experimental plastic Petri's dishes (E.D.) and mineralized-nodules formation, at the microscopical level, was evaluated in comparison to HA-free control dishes (C.D.) after 21 days. Little colony formation occurred in presence of HA, whereas CD showed normal cell confluence with mineralization of nodules even at 10 days. However, when harvesting was performed from both dishes after only 12 hours, before cell aggregation occurred, cell confluence and nodule formation could be seen with no apparent difference between test and control. This study shows that, with respect to PDL cells, hyaluronan seems to inhibit cell adhesion, although with no interference with cell aggregates calcifying potentials. This latter finding may: a) provide further insight in analyzing the properties of extracellular matrix substrates in the PDL environment, b)guide research to possible explanations on how the PDL maintains its characteristics of uncalcified tissue and c) lead to theorize regarding utilization in tissue regeneration. (Journal of Applied Biomaterial & Biomechanics 2003; 1: 84-90).

Purpose: The microbial colonization of new ceramic materials developed for abutment manufacturing was assessed., Materials and Methods: The materials used in these experiments were disks of 'as-fired' and 'rectified' ceramic material made of tetragonal zirconia polycrystals stabilized with yttrium (Y-TZP) and commercially pure grade 2 titanium (Ti) with corresponding eluates. They were tested in vitro with the following bacteria: Streptococcus mutans, S. sanguis, Actinomyces viscosus, A. naeslundii, and Porphyromonas gingivalis. Proliferation was evaluated on plates by inhibitory halos around pits, previously inoculated with eluates obtained from the materials. Bacterial adhesion on materials was quantified by spectrophotometric evaluation of the slime production by the same bacteria. Moreover, early bacterial adhesion was evaluated in human volunteers and observed with SEM., Results: No inhibition of bacterial proliferation using eluates was observed. In vitro as-fired and rectified Y-TZP showed significantly more adherent S. mutans than did Ti disks, while S. sanguis seemed to adhere easily to Ti specimens. No differences were noted for Actinomyces spp and P. gingivalis. In vivo Y-TZP accumulated fewer bacteria than Ti in terms of the total number of bacteria and presence of potential putative pathogens such as rods. No differences were observed between rectified and as-fired Y-TZP., Discussion: Overall, Y-TZP accumulates fewer bacteria than Ti., Conclusion: Y-TZP may be considered as a promising material for abutment manufacturing.

Background: The osteoinductive effect of some biomaterials could be affected by those systemic conditions typical of old age. The aim of the present paper was to assess the effects of age on the healing of bone defects treated with demineralized bone matrix (DBM)., Methods: The study was conducted in young (3 month old) and aged (18 month old) rats to assess the efficacy of DBM in the treatment of osseous defects in bone with limited repair capacities. A standard bone defect was created in the distal femoral condyles of male Wistar rats: the left condyle was filled with rabbit DBM granules, while the right condyle was left empty (control). Histological and microhardness analyses were performed at 30 and 45 days after implant surgery., Results: After implantation of xenogenic DBM, bone healing areas of the aged and young groups showed a significant increase in the formation of newly mineralized bone relative to controls. Measurements of trabecular thickness on day 45 revealed no differences between newly formed and preexisting bone in the young group, while control values were lower. Microhardness measurements demonstrated that newly mineralized bone, either induced by DBM or not, and preexisting bone were comparable in terms of trabecular hardness after 45 days., Conclusions: In conclusion, xenogenic DBM seems to be effective in bone defect healing, since it increases mineralized tissue volume. In both DBM-filled and empty sites, age seems to have a detrimental effect on the volume of new bone formation but no influence on bone maturation.

The improvement of the implant-bone interface is still an open problem in the long-term mechanical stability of cementless fixed implants. Mechanical, histomorphometric and bone hardness measurements were performed in sheep femoral cortical bone implants at 8 and 12 weeks from surgery to compare in vivo the osseointegration of titanium screws (psi 3.5 mm x 7 mm length) with two different surface treatments: sandblasting with 70-100 microm HA followed by acid etching with HNO3 (Group A) and Ca-P anodization followed by a hydrothermal treatment (Group B). No significant differences were found for maximum push-out force and interfacial strength between groups at both experimental times. No significant difference was observed for Bone Ingrowth between groups at both experimental times, while the Affinity Index of Group B was significantly higher (7.5%, p<0.05) and lower (10.2%, p<0.05) than that of Group A at 8 and 12 weeks, respectively. Finally, a significant increase in bone microhardness measured within 200 microm from the interface and inside the thread depth of Group A was observed between the two experimental times (p<0.05). In conclusion, present findings show that osseointegration may be accelerated by adequate surface roughness and bioactive ceramic coating such as current tested treatments which enhance bone interlocking and mineralization.

Effects of pulsed electromagnetic fields (PEMFs, 75 Hz. 1.6 mT) were investigated in 12 rabbits after placing hydroxyapatite (HA) implants in their femoral condyles. Six animals were stimulated with PEMFs for three consecutive weeks, 6 h/day, while the remaining animals were sham-treated (Control Group). Rabbits were sacrificed at 3 and 6 weeks (after a 3-week non-stimulation period) for histomorphometric analysis and microhardness testing (at 200, 500, 1,000, 2,000 microm from the implant) around the implants. Histomorphometric analysis did not highlight any significant changes. On the contrary, there were statistically significant differences between the effects produced by PEMFs and Control Groups (F = 149.70, p < 0.0005) on the Affinity Index results, as well as by the experimental time of 6 and 3 weeks (F = 17.12, p = 0.001) on the same results. In PEMF-stimulated animals the microhardness (HV) values measured in trabecular bone at a distance of 200 and 500 microm from the implants, were significantly higher with respect to controls. At 6 weeks, HV values at the bone-implant interface in PEMF-stimulated animals were not significantly different with respect to normal bone, while they remained significantly lower in control animals. Both morphological and structural results demonstrated a positive therapeutic effect of PEMFs in accelerating HA osteointegration in trabecular bone.

Purpose: Histomorphometry and microhardness measurements were performed after Ti6AI4V implantation in cancellous and cortical bone of healthy and ovariectomized animals to determine characterization of the bone-biomaterial interface in osteopenic bone., Materials and Methods: Nine ovariectomized and 9 sham-aged rats were used. Four months later, nails were implanted in the distal femurs, and the animals were sacrificed after 8 weeks. Moreover, 3 ovariectomized and 3 sham-aged sheep were used. Twenty-four months later, screws were implanted in the tibial diaphyses and the animals were sacrificed after 12 weeks., Results: Histomorphometry showed the development of osteopenia in both trabecular and cortical bone, and revealed a significant decrease in the osseointegration rate in osteopenic versus sham-aged animals for both trabecular (Affinity Index: -18.6%, P < .001) and cortical bone (Affinity Index: -23.5%, P < .005; Bone Ingrowth: -9%, P <.05). At the interfaces of the sham-aged animals in both trabecular and cortical bone, a decrease of bone microhardness was observed in comparison with preexisting bone (trabecular: -9.8%, P < .0005; cortical: -19.3%, P < .0005). In case of osteopenia, this decrease was even more extensive (trabecular: -15.5%, P < .0005; cortical: -24.7%, P < .0005)., Discussion: The present data suggest that bone formation around Ti6AI4V was not associated with complete bone maturation, even in healthy animals. In case of osteopenia, both bone formation and maturation were delayed., Conclusion: These results apparently demonstrate the utility of investigating biomaterials in osteopenic bone and the importance of careful evaluation of the healing rate and bone maturation degree around implanted biomaterials.

Background: Microbial internal contamination of oral implants has been suggested as being responsible for inflammatory infiltration of peri-implant tissues at the fixture-abutment interface of 2-stage and 2-component implant systems; it is also considered as a potential source of pathogens. The present in vivo study evaluated contamination of the inner abutment-implant retaining screw, after occlusal loading and provisionally-luted reconstruction with or without a washer device., Methods: Eight 2-component oral implants sealed with an o-ring silicon washer device and 9 without a seal were placed in 7 patients with high oral hygiene standards. Two months after prosthetic reconstruction, crowns and internal screws were removed, and organic and inorganic screw contamination was examined by scanning electron microscopy and energy dispersive x-ray spectroscopy (EDS) analysis., Results: An amorphous and crystalline contamination, suggestive of calcium and phosphate compounds, was seen on all screw surfaces. Microbial contamination was more frequently observed in the unsealed group. No differences in bacterial morphotypes were observed between the sealed and unsealed implants. Cocci were the most representative morphotypes, while rods were seldom seen., Conclusions: In clinical situations, leakage occurs at the implant-abutment interface, although bacterial contamination is limited in patients with high oral hygiene standards. Contamination may be reduced by using a washer device.

Background/aim: The aim of this study was to assess the oral hygiene attitude and the professional preventive examination compliance in Italian university students., Method: A sample of 202 students attending the University of Bologna was randomly selected and interviewed about their preventive oral health attitude and compliance. All students reported using toothpaste and most of them (92.1%) brushed their teeth at least 2x a day using artificial, medium stiffness bristles. The toothbrush was generally (81.6%) replaced within 3 months. Few subjects (14.9%) said they used dental floss daily or utilized other devices. A majority of subjects (59.9%) had a dental examination within the year previous to the interview. Cluster analysis was performed., Results: 4 groups were identified with homogeneous oral hygiene behavior and compliance toward professional preventive examination. Only one cluster, representing 33.6% of the sample, showed consistent frequency and modalities of oral hygiene habits. The other clusters seemed to be defective with interproximal cleaning procedures and compliance toward professional preventive care. Since the sample was characterized by a young, urbanized, homogeneous group with a high educational level and frequently from an upper middle class social status, the analysis probably gives a supra-estimation of the positive behavior., Conclusion: It is rational to suppose that strategies to promote dental service utilization, patients' compliance and a professional style oriented toward prevention may be useful to improve the oral health condition in the young adult Italian population.

This study evaluated, in vitro, the effectiveness of diamond and carbide burs, and bur sequences to remove the plasma-sprayed titanium coating from IMZ fixture surfaces. Fifteen polishing procedures were tested. They included the use of 12, 16, 30 bladed carbide burs or bevered carbide burs and 30, 15, 8 microns mean-particles-size diamond burs. The treated surfaces were evaluated with profilometer and SEM. Worn burs and titanium debris produced by the grinding were observed with SEM. All procedures produce smoother surfaces than baseline plasma-sprayed surfaces for both Ra and Rz(DIN) parameters (P < 0.001). A roughening effect of the 8 microns mean-grit diamond bur and 30 bladed burs were noted. The single carbide burs produce polished surfaces affected by waviness. Waviness was minimized by sequence or diamond bur use. The carbide bur blades were variously damaged after their use. In contrast, the grit of diamond burs was observed to be clogged by titanium debris whose amount seemed to be inversely related to the diamond mean particle size. Debris produced by diamond burs was granular whereas that produced by carbide bladed burs showed needle or flake morphology. In conclusion, the most effective titanium plasma sprayed removal were obtained by 30 microns and 15 microns mean-particle-size diamond burs, i.e. 30 microns plus 15 microns diamond burs and carbide 12 plus 16 bladed burs used in sequence.

Background/aims: Assessment of the influence of toothbrush wear on plaque (PI) and gingival (GI) indexes., Method: 20 university students were recruited. PI and GI were recorded at the starting point (T0). Each subject received a toothbrush and toothpaste. 5 measurements of toothbrush were recorded to establish the initial size. The subjects were instructed to brush 3 x a day and to refrain from using other plaque removal aids. After 1 month (T1), the subjects were randomly divided into 2 groups: group no. 1 substituted the toothbrush at each monthly visit; group no. 2 brushed only with the toothbrush provided at T0. Recalls were scheduled after 1 (T1), 2 (T2) and 3 months (T3). PI, GI and an index of wear (WI) were calculated using 5 measurements of the toothbrush head and were recorded at recalls., Results: From T0 to T3, a significant increase of PI was found within both groups. Non-significant differences, but very close to the significant level (p= 0.063), in group no. 1 and significant differences in group no. 2 of GI were found. No significant differences of PI and GI were found between groups. Increase of the WI was registered from T0 to T3 (p<0.001)., Conclusion: Each individual is capable of maintaining low PI, even if using a toothbrush that shows evidence of wear.

Objective: The aim of this open trial was to test the efficacy of granulocyte-macrophage colony-stimulating factor (GM-CSF) mouthrinses as a potential treatment in reducing the duration of severe oral mucositis in patients undergoing bone marrow transplantation for hematologic malignancies., Study Design: The study group was composed of 10 consecutive patients suffering from severe oral mucositis during bone marrow transplantation procedures. The control group was similar to the study group in age and gender and comprised 29 historical patients with similar clinical characteristics. Freshly prepared GM-CSF mouthwash (0.5 microg/mL) was administered to the study population for 1 minute 3 times per day after oral hygiene procedures, starting from the first day of mucositis until clinical improvement of oral lesions. The study and control populations were compared with respect to duration of severe oral mucositis (1-9 days, 10-19 days, > or =20 days)., Results: There was no statistically (chi2 exact test) significant difference in mean mucositis score between the study group (11.9+/-6.1) and the control group (16.6+/-8.9). However, the duration of severe mucositis appeared to be reduced; 60% of the GM-CSF mouthrinse patients had severe mucositis for less than 9 days, whereas only 28% of the controls had severe mucositis for less than 9 days. In addition, 10% of the GM-CSF mouthrinse patients experienced severe mucositis lasting 20 or more days, whereas 34% of the controls experienced severe mucositis for 20 or more days., Conclusions: These findings suggest that GM-CSF may reduce the duration of severe mucositis, but controlled, double-blind clinical trials are now required.

Objective: To compare topically applied mesalazine (5-aminosalicylic acid) to topically applied clobetasol propionate in the treatment of patients suffering from symptomatic oral lichen planus., Design: Randomized controlled longitudinal investigation., Patients and Methods: Twenty-five out-patients suffering from oral lichen planus and referred to the Department of Oral Pathology and Oral Medicine of the University of Milan, Italy, during the period January to August 1997. Patients were randomly allocated (Group A and Group B) to treatment with mesalazine 5% or clobetasol propionate 0.05%. The drugs were topically applied twice daily for 4 weeks. Discomfort and pain were evaluated by the patient before and after treatment using a Visual Analogue Scale from zero (no pain) to 10 (extreme pain). Results were statistically evaluated by a Mann-Whitney U test., Results: The two pharmacological regimens obtained partial and complete absence of symptoms. In particular, the mesalazine tested group disclosed 57% complete absence of symptoms, 21.3% partial response and 9% no response. No statistically relevant difference has been detected between the two regimens., Conclusions: The results of this preliminary study, if confirmed by further investigations, suggest that mesalazine might be considered an alternative to clobetasol propionate for treatment of symptomatic oral lichen planus.

THE STUDY ASSESSES IN VIVO the surface roughness necessary to reduce plaque colonization on titanium after 24 hours. Three groups of 16 titanium disks were assigned to 3 different polishing groups (A, B, and C). The roughness was evaluated with a laser profilometer and the morphology with a scanning electron microscope (SEM). Eight volunteers were enrolled and two stents were applied in the mandibular posterior region of each. Each stent supported 3 disks, one per group. The volunteers suspended oral hygiene for 24 hours, after which the stents were removed; one was processed for evaluation of the adherent biomass and the other for SEM study. On each specimen a global area of 100 x 125 microns was examined with SEM. The area was composed of five 20 x 25 microns randomly selected fields. For each field the density of bacteria and the morphotypes were recorded. The data quoted for the global area are cumulative of those observed in the 20 x 25 microns fields. Group A had a significantly smoother surface than groups B and C. The adherent microbial biomass determination and SEM evaluation revealed that group A contained less bacteria than the roughest group. The bacterial population was composed of cocci in group A, and of cocci and short and long rods in groups B and C. We conclude that a titanium surface with Ra < or = 0.088 microns and Rz < or = 1.027 microns strongly inhibits accumulation and maturation of plaque at the 24-hour time period and that such smoothness can be achieved in transgingival and healing implant components.

The aim of the study was to evaluate the smoking habits of Northern Italian dental practitioners and their basic skills in the prevention of oral cancer. 217 of the 250 dental practitioners (86.8%) contacted by telephone from September to December 1994, answered a simple questionnaire. One third of the sample interviewed was formed by current smokers; nevertheless 60.8% of them always advise their patients to give up smoking. Only a relatively small percentage of the questioned dental practitioners (10.6%) do not examine the oral mucosa of the patients on a regular basis and 40% of responders had made a clinical diagnosis of oral cancer in the past. The lack of a specific dental education was associated with less scrupulous examination of the oral soft tissues and minor experience of cancer diagnosis. Despite their smoking habit, Northern Italian dental practitioners self-reported encouraging behaviour towards primary and secondary oral cancer prevention.

Patients with cervical dentine exposures do not always complain of dentine hypersensitivity. The identification of morphological features connected to symptoms is important for both prevention and management of dentine hypersensitivity. The aim of the study was to determine the relationship between the dentine ultrastructure and clinical symptoms in patients with cervical dentine exposures. Replica models for a total of 28 teeth (from 10 patients) with cervical non caroius lesions and dentine exposures were obtained before and after acid etching. The replica models were studied blindly in the scanning electron microscope (SEM). 12 of these were classified clinically as hypersensitive and 16 as non-sensitive. Because of the morphological heterogeneity of all specimens, a grid was used to isolate smaller, more homogeneous areas. 120 (75 non-sensitive and 45 hypersensitive areas) grid areas randomly selected from the 28 dentine surfaces were analyzed. The presence and morphology (amorphous or crystalline) of smear layers and the density and diameter of dentine tubules were recorded. The chi 2 test was used for statistical analysis. In unetched specimens, the surfaces classified as non-sensitive were frequently coated by an amorphous smear layer (88.0%) and occasionally by a crystalline smear layer (2.7%). Only a few and narrow tubules were observed (9.3%). On the other hand, the unetched specimens of the hypersensitive dentine exhibited less frequently (31.3%) an amorphous smear layer. The presence of crystalline smear layer (33.3%), many and wider patent tubules and, sometimes, loss of intertubular dentine manifested as grooves between tubules, were observed (35.6%). The differences were significant (p < .001). In hypersensitive dentine, the acid etching always removed the smear layer whereas removal in non-sensitive dentine was partial or absent. These morphological findings underline the rôle of smear layer in reducing permeability of dentine in patients with dentine sensitivity.

The endodontic anatomy of primary molars is difficult to predict because of the balance of resorption and hard tissue deposition. In particular, the resorption causes perforating lacunae across the wall of the root, even at the furcation level, and modifies shape, dimension and position of endodontic apex. The phenomenon can be so deep as to compromise endodontic therapy. The first aim of the study was to verify if reliable criteria can be found for treatability in primary molars undergoing resorption, i.e. if it is possible to predict if perforating lacunae are present or not. The second aim of the study was to verify if other informations needed for endodontic treatment, as shape, dimension and location of the apex, and curvature of the root canal can be predicted. For the study, 80 extracted primary molars, 75 of which pulpally involved by caries, were selected. The treatability was evaluated in term of root length, root shape, dimension and shape of endodontic apex, age of the patient and X-ray index of resorption. The association between variables was performed by multiple correspondence analysis. The results suggested that root length was the most reliable criterion of the integrity of the root. The borderline of treatability was at the length of 4 mm. The position of endodontic apex related to anatomical apex, and the lingual related to the buccal root length were analyzed by linear regression analysis. The canal length was often similar to the root length (i.e. the endo and anatomical apices were very close) in lower and upper molars. However, in lower molars, if two or more canals were present in the same root, a discrepancy was observed between buccal and lingual root length. This finding was constant in first lower molars. In addition regression analysis provided a linear function between the lengths of the buccal and lingual side of the same root in lower molars. Its coefficient b was 0.73.

Early extraction of carious primary teeth may result in functional and/or loss of arch length problems. That is the rationale behind root canal therapy and/or space maintenance after the extraction of pulpally involved primary molars. What follows is a short radiographic and photographic history of unexpected results in well established and routine space therapy treatments.

Tunnel preparations for restoration of Class II carious lesions in primary molars preserve the marginal ridge and minimize sacrifice of healthy tooth substructure. Materials with improved bonding to tooth structure and increase potential for fluoride release allow Class II restorations without "extension for prevention".

Correct endodontic treatments will be produced if the quality control of intra-operatory dental roentgengraphic displays an adequate periapical coverage. The degree of anatomic accuracy of Rx images depends on correct technical procedure which includes exposure, angulation, object-film and focal-film distance. According to many Authors only the paralleling extended-distance technique provides the minimum of dimensional distortion.

Restorative treatment of largely destroyed first permanent molars in the mixed dentition involves a few peculiar considerations. Special attention must be given to the restorative-periodontal relationship.