Proanthocyanidin may improve the shear bond strength at the composites/dentine interface

TThis study aimed at assessing whether proanthocyanidin, a collagen cross-linker, affects the adhesion strength of resin composites on the dentine surface. Freshly extracted, caries-free, human molars (N=55) were embedded in transparent resin and bisected. The halves were then assigned to either a treated or a non-treated group, where the treatment consisted of a 10 min incubation in a 6.5% proanthocyanidin solution in PBS. A resin composite cylinder was polymerized perpendicularly to the dentinal surfaces and shear tests were made, using an Instron-like machine. The fracture surfaces were characterized by optical (Picro-Sirius Red stain) and electron microscopy (FESEM EDX analysis). Mean bond strength values were 10.73 MPa (SD 3.70) for the treated group and 8.69 MPa (SD 3.20) for the non-treated group (p less than 0.05 Student’s t-test). No constant fracture patterns could be found within the two groups. Proanthocyanidin treatment may improve the adhesion properties of the dentine-bonding interface.

Treatment of symptomatic oral mucositis with sodium hyaluronate and synthetic amino acid precursors of collagen in patients undergoing haematopoietic stem cell transplantation

The purpose of the study is to evaluate the clinical effects of Mucosamin® (a spray preparation containing sodium hyaluronate combined with a pool of amino acids of precursor collagen, including L-Proline, L-Leucine, L-Lysine and glycine) on wound healing and pain management of oral mucositis after hematopoietic stem cell transplantation. The importance of professional dental hygiene by dental hygienist in reducing the severity of oral mucositis as unique therapy or in addition to therapy with Mucosamin® was also evaluated. One hundred thirty-seven patients undergoing hematopoietic stem cell transplantation were recruited in a case-control study and divided into 4 groups: Group A: professional oral hygiene + Mucosamin®; Group B: professional oral hygiene + standard treatment with chlorhexidine 0.20%;; Group C: only Mucosamin®; Group D: only standard treatment with chlorhexidine 0.20%. The following evaluations were made: WHO mucositis scale, OMAS mucositis scale, VAS, periodontal recording, days of mucositis. Comparing the groups at the onset of OM on WHO scale, it was observed that Group A grade 1 occurrence was more statistically significant than Group B (p= 0.03*); comparison between Group A and D showed a statistically significant difference in favour of Group A (p= 0.0002*). Also OMAS scale showed a statistically significant difference between groups who assumed Mucosamin, who developed lower OM grade (p = 0.001*). There was a statistically significant difference between group A compared with group B over the overall duration of OM (p = 0.02*), as well as between group A and group D (p=0.03*). According to the present study the combination of a careful debridement, correct oral hygiene during hospitalization and the use of Mucosamin® exponentially reduces the severity and duration of mucositis and consequently the discomfort of the patient. Moreover, it can be stated that the use of Mucosamin® also results in a reduction in the extent of chemotherapy lesions. Hyaluronic acid and amino acid-based sprays can be a valuable therapeutic aid in the treatment of mucositis.

Randomized, placebo-controlled, double-blind trial of clobetasol propionate 0.05% in the treatment of oral lichen planus

OBJECTIVE

To perform a randomized, placebo-controlled, double-blind study, with a follow-up period of 6 months, for the use of topical clobetasol in cases of symptomatic oral lichen planus (OLP).

SUBJECTS AND METHODS

Thirty-two participants were analyzed, with the aims of: (I) to compare the usefulness of topically applied clobetasol propionate 0.05% (mixed with 4% hydroxyethyl cellulose gel) and 4% hydroxyethyl cellulose gel alone (considered as placebo) in the management of OLP; (II) to describe which of them is quicker in decreasing signs and reported symptoms, and (III) which is able to give the proper longer remission in the follow-up.

RESULTS

Symptoms improved in all clobetasol-treated patients during the first 2 months of therapy, while only 50% of placebo control group (p = .005) displayed similar results; of the remaining half, 12.5% did experienced a worsening while 37.5% remained stable. Regarding clinical signs, 87.5% of clobetasol-treated patients improved, while only 62.5% of the placebo-treated patients had a positive response (p = .229).

CONCLUSIONS

It is possible to report that clobetasol, at this dosage, has been more effective than a placebo at provoking symptoms improvement in subjects affected by atrophic-erosive oral lesions.

Influence of Mastication on Gastric Emptying

The role of mastication on digestion efficiency remains to be demonstrated. This study investigates whether masticatory function influences gastric emptying rate. Twelve normal volunteers were studied on two occasions after ingestion of the same test meal containing ham cubes, crackers, and egg (mixed with 13C-octanoic acid), chewed, in random order, either with 50 masticatory cycles or with 25 cycles, swallowing ham cubes whole. Lag phase (Tlag) and gastric half-emptying time (T½) were measured by means of the 13C-octanoic acid breath test. Trituration performance was assessed by the sieve test, and was expressed as the percentage of ham particles ≤ 1 mm after 50 masticatory cycles. Tlag and T½ were significantly shorter when the meal was chewed with 50 cycles than with 25 cycles (Tlag 25.9 ± 3.8 vs. 36.4 ± 4.1 min, p = 0.017; T½ 49.1 ± 5.7 vs. 62.5 ± 6 min, p = 0.009). Trituration performance was inversely related to both Tlag (r = 0.621, p = 0.031) and T½ (r = 0.699, p = 0.012). Comminution of food influences significantly gastric emptying rates.

Use of sodium hyaluronate and synthetic amino acid precursors of collagen for the symptomatic treatment of mucositis in patients undergoing haematopoietic stem cell transplants

Oral mucositis (OM) may occur in up to 100% of patients undergoing condition regimen to hematopoietic stem cell transplant (HSCT). From the patient’s perspective, OM is one of the most debilitating side effects of transplantation. It is commonly thought that oral hygiene can modify the incidence and severity of oral mucositis, therefore professional oral health care (POHC) is recommended prior to conditioning regimen for HSCT. A new strategy for the treatment of OM is sodium hyaluronate (SH) combined with amino acid precursors of collagen (Aas) (Mucosamin®). SH is a mucoaderent polymer acting as a mechanical barrier and pain reliever. Furthermore, it allows prolonged contact of the product with the mucous membrane. In this study, a total of 68 adult patients due to undergo HSCT for allogenic and autologous transplant were enrolled at the Stem Cell Transplant Unit. The patients were divided into two groups. One group was treated with POHC before HSCT and applications of Mucosamin® during the recovery after transplantation. The second group served as controls, with the usual treatment of Clorexidine 0.20% adopted by the department. After HSCT the same clinician, an expert in oral medicine trained for the clinical trial, evaluated symptoms of the patients’ mucositis of both groups every day. The treated patients developed less severe OM, therefore Mucosamin® seems to have a protective role against the more severe phases of mucositis. The maximum OM pain, measured with the VAS scale, was higher in patients who did not use Mucosamin®. In the treated group OM resolved sooner than in the control group.

Cytokine, chemokine, and growth factor profile of platelet-rich plasma

During wound healing, biologically active molecules are released from platelets. The rationale of using platelet-rich plasma (PRP) relies on the concentration of bioactive molecules and subsequent delivery to healing sites. These bioactive molecules have been seldom simultaneously quantified within the same PRP preparation. In the present study, the flexible Bio-Plex system was employed to assess the concentration of a large range of cytokines, chemokines, and growth factors in 16 healthy volunteers so as to determine whether significant baseline differences may be found. Besides IL-1b, IL-1ra, IL-4, IL-6, IL-8, IL-12, IL-13, IL-17, INF-γ, TNF-α, MCP-1, MIP-1a, RANTES, bFGF, PDGF, and VEGF that were already quantified elsewhere, the authors reported also on the presence of IL-2, IL-5, IL-7, IL-9, IL-10, IL-15 G-CSF, GM-CSF, Eotaxin, CXCL10 chemokine (IP-10), and MIP 1b. Among the most interesting results, it is convenient to mention the high concentrations of the HIV-suppressive and inflammatory cytokine RANTES and a statistically significant difference between males and females in the content of PDGF-BB. These data are consistent with previous reports pointing out that gender, diet, and test system affect the results of platelet function in healthy subjects, but seem contradictory when compared to other quantification assays in serum and plasma. The inconsistencies affecting the experimental results found in literature, along with the variability found in the content of bioactive molecules, urge further research, hopefully in form of randomized controlled clinical trials, in order to find definitive evidence of the efficacy of PRP treatment in various pathologic and regenerative conditions.

Overcoming physical constraints in bone engineering: ‘the importance of being vascularized’

Bone plays several physiological functions and is the second most commonly transplanted tissue after blood. Since the treatment of large bone defects is still unsatisfactory, researchers have endeavoured to obtain scaffolds able to release growth and differentiation factors for mesenchymal stem cells, osteoblasts and endothelial cells in order to obtain faster mineralization and prompt a reliable vascularization. Nowadays, the application of osteoblastic cultures spans from cell physiology and pharmacology to cytocompatibility measurement and osteogenic potential evaluation of novel biomaterials. To overcome the simple traditional monocultures in vitro, co-cultures of osteogenic and vasculogenic precursors were introduced with very interesting results. Increasingly complex culture systems have been developed, where cells are seeded on proper scaffolds and stimulated so as to mimic the physiological conditions more accurately. These bioreactors aim at enabling bone regeneration by incorporating different cells types into bio-inspired materials within a surveilled habitat. This review is focused on the most recent developments in the organomimetic cultures of osteoblasts and vascular endothelial cells for bone tissue engineering.

Alumina-zirconia composites functionalized with laminin-1 and laminin-5 for dentistry: effect of protein adsorption on cellular response

The present paper describes a study on laminin interaction with the surface of two alumina-zirconia composites with different percentages of ZrO2, both with submicrometric grain size. As major molecules within the basement membrane (BM), laminins are important protein fragments for epithelial cell adhesion and migration. On the other hand, alumina-zirconia composites are very attractive materials for dental applications due to their esthetic and mechanical properties. X-Ray photoelectron spectroscopy and atomic force microscopy were used to study the adsorption of two types of laminin, laminin-1 (Ln-1) and laminin-5 (Ln-5), onto the ceramics surfaces. The in vitro cell response was determined by intracellular phosphorylation of major kinases. Ceramics samples functionalized with laminins showed better cellular activation than untreated specimens; furthermore, cellular activation was found to be greater for the composite with higher percentage in zirconia when functionalized with Ln-5, whereas the adsorption of Ln-1 resulted in a greater activation for the alumina-rich oxide.

Healing properties of implants inserted concomitantly with anorganic bovine bone. A histomorphometric human study

BACKGROUND

The present prospective, randomized, double-blind study evaluated the bone-forming process around implants inserted simultaneously with anorganic bovine bone (ABB) in sinus grafting.

METHODS

A total of 18 threaded mini-implants with Osseotite (O) and Nanotite (N) surfaces were placed in seven patients (nine sites). After 12 months, the implants were retrieved and processed for histological analysis. A total of 18 cutting and grinding sections were investigated with bright-field light microscopy, circularly polarized light microscopy (CPLM), confocal scanning laser microscope (CSLM), and scanning electron microscope (SEM) with energy dispersive spectrometer (EDS).

RESULTS

The bone-to-implant contact rate in native crestal bone was 62.6 ± 0.4% for N implants and 54.3 ± 0.5% for the O implants (p = 0.001). The collagen fibre density, as assessed by CPLM, was 79.8 ± 6.0 nm for the N group and 74.6 ± 4.6 nm for the O group (p < 0.05). Line scan EDS starting from ABB to newly formed bone showed a decrease in calcium content and an increase of carbon while phosphorus content was constant.

CONCLUSIONS

While the N surface improved the peri-implant endosseous healing properties in the native bone, when compared to the O surface, it did not improve the healing properties in the bone-graft area.

Exposing human epithelial cells to zoledronic acid can mediate osteonecrosis of jaw: an in vitro model

BACKGROUND

Osteonecrosis of the jaw (ONJ) is a chronic complication of bisphosphonate therapy, mainly when intravenous, in cancer patients with bone metastases and myeloma. Its pathophysiology is not yet fully elucidated; in particular, the molecular/cellular events triggering ONJ remain unclear. This complication could result from the effect of bisphosphonates released from bone into the soft-tissues, or from osteolysis induced by soft-tissues directly exposed to bisphosphonates. This research investigated the possibility that ONJ may be evocated by changes induced in osteoblast activity by factors released by soft-tissue cells exposed to zoledronic acid.

METHODS

An 'in vitro' model was used, in which human osteoblast-like MG-63 cells were grown in medium conditioned by human keratinocytes NCTC 2544, exposed or not to zoledronic acid (5 or 50 μM); 5 μM zoledronic acid was also directly administered to MG-63 cells.

RESULTS

In NCTC 2544 cells, zoledronic acid decreased proliferation via decreased hydroxy-3-methyl-glutaryl-CoA reductase, suggesting that a decrease in healing capability can occur in case of injury. An increased pro-inflammatory potential was also observed. Osteoblasts grown in medium conditioned in the presence of zoledronic acid showed decreased proliferation and osteogenic properties, and increased ability to induce osteoclast differentiation and inflammatory process. Zoledronic acid directly administered to MG-63 modulated only some parameters and in a lesser extent.

CONCLUSIONS

The research evidenced, for the first time, the direct involvement of epithelial cells in zoledronic acid-triggered molecular mechanisms leading to osteonecrosis of the jaw, by modulating both osteoblast and osteoclast properties.

Transglutaminase 2 expression is significantly increased in cyclosporine-induced gingival overgrowth

Cyclosporine A is a potent immunosuppressant used to prevent organ transplant rejection and treat various autoimmune diseases. However, cyclosporine A can also induce gingival overgrowth, which is characterized by increased extracellular matrix due to an altered balance between collagen synthesis and degradation. This study proposed to verify whether trans-glutaminase 2, an enzyme thought to be responsible for the assembly and remodelling of extracellular matrix, plays any role in the pathogenesis of cyclosporine A-induced gingival overgrowth. Cyclosporine A-induced gingival overgrowths were collected from 21 liver transplant patients and case-controlled with 20 non-hyperplastic gingival biopsies from healthy patients who had previous periodontal treatment. In both groups, the presence and tissue distribution of transglutaminase 2 were determined by immunohistochemistry and analyzed in comparison with the tissue morphology and expression of lymphocyte-related antigens (CD3 and CD20) and a vessel-related marker (CD34). Transglutaminase 2 expression showed a significant increase (2.6-fold) in the stromal component of cyclosporine A-treated patients compared with controls (p<0.001), which suggested that transglutaminase 2 had a role in the pathogenesis of the disease. Further studies should investigate the therapeutic effect of anti-transglutaminase 2 drugs (putrescine or 1,4-diamino-butane) in these patients.

Cephalometric evaluation of the upper airway in patients with complete dentures

AIM

Obstructive sleep apnea syndrome (OSAS) is a disorder characterised by repeated obstructions of the upper airway, with consequent episodes of apnea and hypopnea during sleep, snoring, and daytime sleepiness. Recently, a role of edentulism in the occurrence or in the worsening of this disorder was suspected. The aim of the study was to assess, through a cephalometric analysis, if the removal of denture induces, and where, modifications that can favour the pharynx collapse.

METHODS

A total of 27 subjects with complete or partial loss of teeth and with heavy loss of the vertical dimension, were examined. The patients were submitted to radiographs of the cranium in supine position, to simulate as much as possible the night condition, with the denture in intercuspal position (ICP), and in relaxed position both with denture (D-RP) and without it (edentule-relaxed position, E-RP). The radiographs were analysed through specific measures for OSA evaluating the parameters that could be modified by the denture.

RESULTS

The pharyngeal airway space (PAS) decreases, at the level of uvula, from ICP (6.7 mm) to RP (5.3 mm) (P< 0.05). The distance between the base and the tip of the tongue significatively decreased both from ICP vs E-RP (7.35 mm vs 6.87 mm; P< 0.05), both from D-RP to E-RP (7.22 mm vs 6.87 mm; P< 0.005).

CONCLUSIONS

From the data obtained from the cephalometric analysis it seems that wearing denture induces modifications in the position of the tongue, of the jaw and of the pharyngeal airway space that can favour the reduction of apnea episodes.

[In vitro evaluation of chromatic stability in new-generation composites]

BACKGROUND

Ultraviolet light exposure produces chromatic changes in composites used for esthetic restoration. The aim of the study was to compare the chromatic changes induced by accelerated aging in two composites of new generation: Tetric Ceram and Diamond Crown.

METHODS

Five samples were prepared for each composite, each divided into two pieces, one exposed to accelerated aging obtained by ultraviolet-light exposure for 24 hours, and one maintained in dark. Thereafter, the samples were lighted by a light beam and the percentage of reflected light was assessed. The distribution of the levels of red, green and blue was assessed using a camera connected to a PC with a software for image processing.

RESULTS

For both the composites, the values of the three colors were significantly lower in the samples artificially aged (p<0.0001). The values concerning to the Tetric Ceram were significantly lower than those of Diamond Crown (p<0.0001). The latter showed aging-induced variation significantly smaller than the former.

CONCLUSIONS

Both the composites showed significant chromatic variations after 24 hours artificial aging. Diamond Crown showed significantly better stability.

Influence of mastication on gastric emptying

The role of mastication on digestion efficiency remains to be demonstrated. This study investigates whether masticatory function influences gastric emptying rate. Twelve normal volunteers were studied on two occasions after ingestion of the same test meal containing ham cubes, crackers, and egg (mixed with 13C-octanoic acid), chewed, in random order, either with 50 masticatory cycles or with 25 cycles, swallowing ham cubes whole. Lag phase (Tlag) and gastric half-emptying time (T1/2) were measured by means of the 13C-octanoic acid breath test. Trituration performance was assessed by the sieve test, and was expressed as the percentage of ham particles < or = 1 mm after 50 masticatory cycles. Tlag and T1/2 were significantly shorter when the meal was chewed with 50 cycles than with 25 cycles (Tlag 25.9+/-3.8 vs. 36.4+/-4.1 min, p=0.017; T1/2 49.1+/-5.7 vs. 62.5+/-6 min, p=0.009). Trituration performance was inversely related to both Tlag (r=0.621, p=0.031) and T1/2 (r=0.699, p=0.012). Comminution of food influences significantly gastric emptying rates.

Oral nitric oxide during plaque deposition

BACKGROUND

Nitric oxide (NO) is one of the most powerful antibacterial compounds. We investigated if NO oral production increases during dental plaque deposition.

MATERIALS AND METHODS

Oral NO and salivary nitrite were measured in 31 healthy subjects - 11 smokers and 20 nonsmokers - with natural healthy teeth, in the morning after tooth cleaning (baseline), after withdrawal of oral hygiene for 24 h and again after tooth cleaning.

RESULTS

NO and nitrite were significantly higher during plaque deposition than with clean teeth: mean NO values +/- SEM were 44.3 +/- 4.9 parts per billion (ppb) at baseline, 58.8 +/- 3.7 ppb with plaque and 43.6 +/- 3.7 ppb after tooth cleaning, P < 0.05; nitrite values were 32.9 +/- 5.5 microm at baseline, 66.4 +/- 8.2 with plaque and 37.5 +/- 5.5 after tooth cleaning, P < 0.01. During plaque deposition, oral NO was significantly directly related to salivary nitrite (r = 0.497, P = 0.002) and so were their respective changes after tooth cleaning (r = 0.577, P < 0.001). Smokers had significantly lower oral NO than nonsmokers, with both clean and dirty teeth (P < 0.001), and higher bacteria counts in the plaque (38.6 +/- 11.5 vs. 19.9 +/- 2.3, P = 0.046).

CONCLUSIONS

Oral NO production increases during de novo deposition of dental plaque. NO might be an early host defence mechanism against bacterial proliferation in the plaque. Such a mechanism is inhibited by cigarette smoking.

Effect of edentulism on spirometric tests

The impact of denture wear in edentulous subjects while performing routine spirometric measurements has never been systematically investigated. We compared the values of FVC, FEV(1), PEFR, FEF(50%), FIV(1), and FIF(50%) recorded with and without dentures in three groups of edentulous subjects: 36 asymptomatic subjects with normal spirometry (N), 22 patients with chronic obstructive pulmonary disease (COPD), and 18 with interstitial lung disease (ILD). In 14 subjects retropharyngeal space with and without dentures was assessed by cephalometry. Subjects with N and ILD had significantly lower airflow rates without dentures, whereas subjects with COPD had no significant difference in spirometric values recorded with or without dentures. The retropharyngeal space was significantly decreased by removing dentures (from 1.52 +/- 0.07 to 1.16 +/- 0.09 cm, SEM, p < 0.0001). These findings indicate that in edentulous subjects with a normal or restrictive pattern, the recording of flow-volume curves with or without dentures produces small but significant differences. Although such differences do not appear to have clinical significance, the fact that when dentures are used some respiratory flows are higher would favor the use of dentures in edentulous subjects during spirometric evaluation.

Influence of posts and cores on light transmission through different all-ceramic crowns: spectrophotometric and clinical evaluation

PURPOSE

The influence of different types of posts and cores on light transmission through all-ceramic crowns was assessed by spectrophotometric analysis and clinical evaluation.

MATERIALS AND METHODS

Three extracted natural teeth were replicated in acrylic resin, with roots prepared to receive standardized posts and cores. Using a silicone impression material as a template, various prosthodontic reconstructions were obtained by combining four types of posts and cores (polished and matte-finished gold alloy, all-ceramic, and ceramized metal alloy) and three types of all-ceramic crowns (IPS-Empress 2 surface-colored, IPS-Empress 2 stratified, and In-Ceram). The spectrophotometric analysis was performed in the dark at 25 degrees C. The teeth were backlit with an incandescent lamp at the color temperature of A illuminant and shielded to avoid spurious light entering the spectrophotometer. The transmitted light was analyzed in terms of luminance at four points of the sample surface (cervical, middle, incisal, and proximal). Twelve measurements were performed for the natural teeth, and 144 were performed for the artificial teeth.

RESULTS

Natural teeth had the highest luminance. Among all-ceramic crowns, surface-colored IPS-Empress 2 had the highest luminance, and stratified IPS-Empress 2 had the lowest. Regarding posts and cores, the luminance was highest with the all ceramic, lower with the ceramized and the polished gold alloy (which had very similar luminance), and lowest with the matte-finished gold alloy. No significant difference among prosthodontic combinations was detected under clinical observation.

CONCLUSION

The surface-colored glass ceramic (IPS-Empress 2) was the most translucent crown. At the standard crown thickness used, there were small, significant spectrophotometric, but not clinical, differences among the combinations tested. These findings show no esthetic contraindications for the use of polished gold alloy posts and cores with all-ceramic crowns.

Comparison of marginal fit of 3 different metal-ceramic systems: an in vitro study

PURPOSE

The aim of this study was to compare the marginal adaptation of metal-ceramic crowns made with 3 different metal substructures.

MATERIALS AND METHODS

Seventy-five gypsum dies were fabricated from a master steel die. They were randomly divided into 3 groups of 25 dies each. A metal coping was prepared on each die using a different technique for each group: composite alloy, electroforming, and cast high-noble alloy. Ceramic was baked on all of the samples following the same protocol and simulating the shape and size of a maxillary central incisor. All specimens were evaluated under a stereomicroscope at 200x magnification. The marginal gap was measured at 8 different points on each specimen before and after ceramic application and also on the master steel die. A total of 3,600 measurements was evaluated. The results were statistically elaborated by means of a t test and one-way analysis of variance (ANOVA).

RESULTS

The ANOVA revealed a significant difference in mean marginal gap before and after ceramic application within each group. Electroforming (mean 32 microns) and high-noble alloy (mean 31 microns) showed better marginal fit after ceramic application and on the master steel die compared to composite alloy (mean 68 microns; P < 0.0001).

CONCLUSION

Marginal gaps are influenced by the application of ceramic and by the alloy used for the substructure, and the values obtained were within the limits of clinical acceptability (70 microns).

[Correlation between edentulism, sleep disorders and arterial hypertension. Preliminary research]

BACKGROUND

Respiratory disturbances during sleep are considered risk factors for arterial hypertension and cardiovascular diseases. Edentulism, by decreasing retro-pharyngeal space, may favor upper airway occlusion during sleep. Aim of the study is to evaluate whether edentulism is associated with greater prevalence of sleep disturbances, arterial hypertension and other cardiovascular diseases.

METHODS

Eighty edentulous subjects with dentures (removed during sleep) and 57 subjects with natural teeth, matched for age, underwent assessment of oral conditions and recording of questionnaires on diseases and respiratory sleep disturbances.

RESULTS

Edentulous subjects had a significantly higher prevalence of arterial hypertension and cardiovascular diseases, than subjects with natural teeth.

CONCLUSIONS

In edentulous subjects, removing dentures during sleep may favor respiratory disorders, and increase the risk for hypertension and cardiovascular disease.

[The influence of edentulism on spirometric values]

BACKGROUND

Aim of the paper is to study whether edentulism, by causing a decrease in size and tone of pharyngeal musculature, may affect spirometric measurements.

METHODS

Spirometry was recorded with and without dentures in 58 edentulous subjects, 36 asymptomatic normal subjects (N) and 22 patients with chronic obstructive pulmonary disease (COPD). In 10 subjects retropharyngeal space with and without dentures was assessed by cephalometry.

RESULTS

In the N group, removing dentures produced a significant decrease in lung volumes and airflow rates, while in COPD patients it was ineffective. In both groups, retropharyngeal space was significantly decreased by removing dentures.

CONCLUSIONS

Edentulism, by decreasing extrathoracic airway caliber, influences significantly spirometric measurements in normal subjects but not in those with COPD.

Evaluation of occlusal contacts in the dental laboratory: influence of strip thickness and operator experience

PURPOSE

The purpose of this study was to evaluate the influence of recording strip thickness and of operator-dependent factors on the assessment of contact area on a cast mounted on an articulator.

MATERIALS AND METHODS

Thirteen dental students and 13 experts (dentists and dental technicians) performed occlusal maneuvers on casts mounted on an articulator, using recording strips of 8- and 40-micron thickness. Contact area, force, and time of biting relative to each group of operators using each type of paper were compared.

RESULTS

Both groups obtained significantly greater contact areas with the thicker strip. Students applied significantly stronger but shorter bitings than experts, but obtained smaller contact areas, particularly with the thinner strip. In operators, the extension of contact markings using the 8-micron strip was closely related to the biting time but not to the occlusion force, while neither time nor force of biting had a significant influence when using the 40-micron strip.

CONCLUSION

The assessment of occlusal contact in the dental laboratory was significantly influenced by paper thickness, operator experience, biting force, and time. The 40-micron strip was less influenced by operator experience, strength, and duration of biting.

Bond between gold alloy and ceramic in relation to the thickness of the oxide layer

BACKGROUND

The chemical bonding between metal and ceramic is aided by non-precious metal atoms and their oxides present on the metal surface. Aim of the study was to correlate metal-ceramic bonding with thickness oxide layer on a new gold alloy.

METHODS

Thirty-two specimens were constructed in gold alloy and ceramic, with the aim of evaluating the degree (using shear test) and quality (using optical microscope) of bonding resistance between these materials, in relation to the thicknesses of the oxide layer produced on the metallic parts by means of different thermal procedures.

RESULTS

Bond strength was practically the same with different thicknesses of the oxide layer. A slight reduction in the degree of bonding was observed in the non-oxidised models.

CONCLUSIONS

For the gold-alloy here tested, the oxide layer seems to be not influent in the chemical metal-ceramic bond strength.

In vitro evaluation of fit of adhesively luted ceramic inlays

PURPOSE

The purpose of this study was to evaluate both marginal and overall adaptation of 4 adhesively luted ceramic inlay systems.

MATERIALS AND METHODS

A total of 40 extracted teeth were restored with mesio-occlusodistal ceramic inlays using 4 different techniques: Colorlogic, IPS Empress, Celay direct, and Celay indirect. After cementation with a resin luting agent, the samples were sectioned along a mesiodistal line passing through the center of the restoration. The thickness of the cement was measured at the margins and at several points along the inside of the restorations by means of a stereomicroscope fitted with a measuring grid.

RESULTS

The results were analyzed by one-way analysis of variance. The marginal precision of IPS Empress and Colorlogic inlays averaged below 50 microns. Marginal precision of Celay inlays averaged between 110 and 130 microns. IPS Empress and Celay inlays showed a uniform distribution of the cement along the entire prepared surface. Colorlogic inlays showed an uneven distribution of the cement film.

CONCLUSION

IPS Empress inlays showed the best clinical features compared to Colorlogic and Celay inlays.

All-ceramic restorations: an overview

Advantages and disadvantages of metal-ceramic and all-ceramic restorations are reviewed particularly from the aesthetic point of view. All-ceramic restorations offer the best results because they let the light through optimally. In constructing all-ceramic crowns on teeth which have been endodontically treated, the material used to rebuild the pin-abutments must be taken into consideration if the best aesthetic results are to be achieved. Materials which, because of their translucent characteristics, are the most aesthetic alternatives to metal alloy pin-abutments in rebuilding teeth which have been endodontically treated, are then described.

Effectiveness of the Michigan splint in reducing functional cervical disturbances: a preliminary study

There is controversial evidence for a functional link between the masticatory apparatus and the cervical spine. The aim of this work was to perform a preliminary study to evaluate the effectiveness of the Michigan splint for the treatment of functional cervical disturbances. Forty patients with functional cervical disturbances were randomly organized into test and control groups. The patients in each group were examined by a physiologist to ascertain the extent of functional changes. The test group underwent splint therapy (Michigan type) during a two-month period. The other patients were sent home and did not receive active treatment. After two months, all patients were reassessed physiologically. Cervical pain and pain induced by epispinal or paraspinal pressure were reduced to a statistically significant extent in the treated group, compared with those in the control group.

Oral conditions and aptitude to receive implants in patients with removable partial dentures: a cross-sectional study. part I. oral conditions

The relationship between a removable partial denture (RPD) and damage caused to residual oral structures is the subject of on-going research. A group of patients wearing RPD, treated in the same way in the same department, were recalled to evaluate their oral hygiene and to compare the clinical condition of abutment teeth with that of non-abutment teeth. The study shows that most patients were unable to maintain high standards of oral hygiene. In the group of patients with non-optimal hygiene the clinical condition of abutment teeth was worse than that of non-abutment teeth. In the group of patients with optimal oral hygiene the condition of abutment teeth and non-abutment teeth was almost identical. To increase the standards of oral hygiene it is strongly advisable to recall and follow up patients on a regular basis.

In vitro marginal adaptation of alumina porcelain ceramic crowns

This study evaluated the dimensional stability during firing of In-Ceram alumina porcelain ceramic and examined the marginal fit for three different configurations of tooth preparation. A stereomicroscope was used to measure the space between the margin of restorations and tooth preparations. The three methods of tooth preparation were statistically compared and revealed suitable dimensional stability during the firing and glazing process. A better marginal fit was recorded for artificial crowns fabricated on a chamfer or 50-degree shoulder tooth preparation.

[The evaluation of the efficacy of auxiliary retention in the preparation of partial crowns]

An extracted maxillary human premolar was prepared for 3/4 artificial crown. Ten models of the tooth were made and different combinations of auxiliary retentive components were prepared on each model: proximal and lingual grooves, pins and boxes. For each model an artificial crown was cast cemented to it, mechanically tested for retention and graphed. Pins proved more retentive than grooves, being the latter more retentive when placed asymmetrically more than in symmetrical positioning.

[The incidence of craniomandibular disorders in patients with cervical dysfunctions. A clinico-statistical assessment]

The aim of this research was to measure the incidence of craniomandibular disorders in a group of patients with functional-type cervical alterations. The group consisted of 50 patients undergoing treatment for disorders of the cervical sectors of the spine. Each patient was subjected to a medical examination to investigate the presence of CMD signs or symptoms. From the data statistical analysis a higher percentage of cases with muscular and joint pain, limited mouth opening, deviation and deflection, were found in comparison with the percentage found among the general population. This demonstrates an overloading of the entire masticatory apparatus. Joint noise was less frequent, probably due to its exclusion from our sample of patients with arthrosis-type degenerative pathology.

[Psychometric and psychofunctional studies of a group of patients with craniomandibular disorders]

The base myoelectric of masticatory muscles, and their response to stressor, was studied in a group of patients affected with craniomandibular disorders (CMD) and in a control group. Patients suffering from craniomandibular disorders were affected by at least two of these three groups of symptoms: 1) articular and/or muscular pain; 2) articular noise; 3) alteration of mandibular mobility. The psychofunctional investigation was as follows: in order to measure the base myoelectric activity of the masticatory muscles and their response to stress, the Myotron 222 two-channel electromyographs were used, so as to record the activity of four muscles contemporaneously. The research was conducted on the masseter and anterior fascia of the temporal muscles, which are the most readily accessible of the elevator muscles. A non-specific stressor (shot pistol) was administered to the subjects after the base myoelectric level had been established. These factors were evaluated on the electromyograms: base activity before the stressor; the shape of the response to the stressor; the recovery time after the stressor. The minimum activity before the stressor was usually measured as the minimum activity the subject was able to maintain for roughly one minute. The psychometric investigation used "Minnesota Multiphasic Personality Inventory" (MMPI); this is a nonprojective personality test widely used in clinical psychology. The base level of myoelectric activity was higher in patients affected with craniomandibular disorders than in healthy patients, who generally had low initial values.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical applicability of the radiographic method for determining the thickness of calcified crown tissues

A previously developed radiologic method for determining the thickness of the mineralized crown tissues was applied clinically to 10 teeth diagnosed for extraction. The thickness of the mineralized crown tissues as measured radiographically was compared with that measured directly on the extracted tooth. A statistical analysis indicated accuracy of 4.46%, equivalent to an error of 0.12 mm.

[Occlusion in the etiology of craniomandibular disorders. Current directions]

Craniomandibular disorders are a pathology with a multifactorial genesis where the aetiological aspects it represented by emotional and occlusal factors. These provoke muscular hyperactivity so determining a change in all components of the stomatognathic apparatus. A critical analysis of the literature leads to an analysis of the importance of the occlusal factor in the aetiology of MCD. The conclusions reached are that the ideal occlusion is a theoretical concept. Physiological occlusion is the situation in which, independently of the number, lay-out and relationship between teeth there exists a subjective occlusal stability and a satisfactory masticatory, phonatory and aesthetic function.

[A radiographic assessment of condylar position after therapy with the Michigan plate]

The paper analyses condylar movement in the sagittal plane following four months of therapy using a Michigan-type plate in a group of 19 patients with craniomandibular disorders. An OLTP radiographic examination was used; X-rays carried out before and after therapy were compared using a special image subtraction technique. From the analysis of results it emerged that 63.12% of patients showed a mono- or bilateral condylar movement which was visible by X-ray.

[Extension bridges. A bibliographic evaluation and the clinical indications]

Extension bridges are a valid alternative to partial and implanted prostheses for the rehabilitation of small intercalary or distal lacunae. Following a critical review of published reports on the subject and the assessment of longitudinal studies, the authors examine the clinical parameters and technical procedures used to implement these prosthetic reconstructions.

[An evaluation of the signs and symptoms in patients with craniomandibular disorders correlated with the radiological pictures obtained by OLTP]

The study evaluated the frequency of noise, pain and alterations of mandibular movements in a group of 88 patients. Condylar position was also studied using OLTP X-ray images, and the presence of arthrotic lesions using multitomography. The condylar position was related to the presence of organic lesions at an articular level, and a higher frequency of the latter was found in anterior condylar displacements; the presence of condyles centered in the glenoid cavity on OLTP examination does not exclude the possibility of arthrotic lesions. Another important finding was the observation of a greater frequency of contralateral organic pathologies in posterior condylar displacements.

The unreliability of facial measurements in the determination of the vertical dimension of occlusion in edentulous patients

The aim of this research was to test the reliability of skin markers in the determination of the V.D.O. in edentulous patients during prosthetic rehabilitation. Two resin baseplates were constructed: on the upper one a modified pin of the Central Bearing Point registration device was fixed with impression compound. The height of the pin could be altered by rotating the pin directly in the patient's mouth with a probe. Two lead spheres were inserted on the resin base-plate as bone markers, and two others were fixed to the skin as markers, one above (end of nose) and one below (point of chin) the oral commissure. Five lateral cephalometric radiographs were exposed for each patient, raising the V.D.O. by 1.2 mm on each occasion. Statistical analysis of measurements made on the resulting radiographs showed a very strong correlation between bone markers and pin position, whereas great variation and considerable differences were found between skin markers and bone as well as measurements.

A graphic evaluation of the intermaxillary relationship before and after therapy with the Michigan splint

The effect of the Michigan splint was evaluated graphically in a group of 19 patients. Gothic arch tracings were registered before and after a period of therapy of 4 months, and the two tracings were compared photographically. The position of the apex of the Gothic arch was displaced in most patients, while the shape of the arch was more regular in almost all patients. The validity of the use of the Michigan splint was confirmed.

A radiologic method for determining the thickness of the hard crown tissues

This study describes a radiologic method that provides a reliable evaluation of the thickness of the hard crown tissues of the tooth scheduled for prosthetic and conservative preparation. The first stage consisted of calculating the discrepancy between the actual dimensions of the specimen under examination and the dimensions of the same specimen as measured and radiographed. Some coefficients of distortion were calculated for the distance(s) more usually involved clinically. Radiographs were made by using the "paralleling" technique. In the second stage, radiographs were made of 83 extracted teeth (22 incisors, 12 canines, and 51 premolars). On the resulting radiographs some prefixed distances were measured. Finally, to gain an anatomic comparison of the values obtained radiologically, 24 of the previously radiographed teeth were sectioned along the sagittal plane at the diameter, and measurements were made and compared with the radiologic data to which the correction coefficients had been applied.