Effect of different surface treatments and adhesives on repair bond strength of resin composites after one and 12 months of storage using an improved microtensile test method.

OBJECTIVES: To evaluate the effect of surface treatments and bonding systems on the repair bond strength between composite materials after one and 12 months of storage, using an improved microtensile test method. METHODS: A total of 72 composite cylinders (Tetric Evo Ceram, Ivoclar) were fabricated, stored in distilled water for two weeks followed by thermal cycling (5000 times between 5°C and 55°C), and served as substrate. The cylinders were mechanically roughened using 320-grit silicon carbide sandpaper, etched with 37% phosphoric acid gel, rinsed with water, and divided equally into three experimental groups: group 1, unchanged surface; group 2, sandblasting of the surface (CoJet tribochemical silica sand, 3M ESPE; Microetcher II, Danville Engineering Inc); and group 3, surface silane coating (Bis-Silane, BISCO Inc). Eight control cylinders were prepared and underwent similar aging as the substrate. Each experimental group was divided into subgroups that received the following bonding systems: one-step self-etching adhesive (AdheSE One, Ivoclar Vivadent), two-step self-etching adhesive (Clearfil SE, Kuraray America), and three-step etch-and-rinse adhesive (Adper Scotchbond Multi-Purpose, 3M ESPE). Fresh composite (Tetric Evo Ceram, Ivoclar) was placed and cured on top of the prepared substrate cylinders. The specimens were placed in distilled water for a week and thermocycled the same way as before. Eight composite control cylinders were also stored and thermocycled for the same period of time. Half of the cylinders in each test group were tested at one month and the second half at 12 months. The cylinders were serially sectioned in an automatic cutting machine, producing 10 to 20 1.1 × 1.1-mm test specimen beam from each cylinder. Specimens were prepared for microtensile testing and the tensile strength calculated based on the force at fracture and specimen dimension. The fracture surfaces were examined under a stereomicroscope and the type of fracture noted. RESULTS: The mean tensile strength of composite control was 54.5 ± 6.0 MPa at one month and 49.6 ± 5.1 MPa at 12 months. The mean tensile strength for the repaired groups ranged from 26.4 ± 6.8 MPa to 49.9 ± 10.4 MPa at one month and 21.2 ± 9.9 to 41.3 ± 7.5 at 12 months. There was a statistical difference between all groups (p<0.05) at one month. This difference was less pronounced at 12 months. The highest repair strength was obtained in the group having a silane-coated surface and Clearfil, the two-step self-etching adhesive. Clearfil also had the highest repair strength within each surface treatment group. There was a tendency for lower tensile strength at 12 months compared with one month. Most fractures were of the adhesive type; the highest number of cohesive fractures, 16% at one month and 12% at 12 months, were in groups with the highest tensile strength. CONCLUSION: The best repair bond strength was achieved by using freshly mixed silane solution on the substrate in addition to an adhesive, rendering a thin bonding layer.

Placement and replacement of restorations in general dental practice in Iceland.

Ninety-one Icelandic practicing dentists (51% response rate) provided information related to the reasons for placement and replacement of 8,395 restorations and 741 sealants in 5,997 patients. Information included the patient's gender and age, the clinician's gender and experience in years since graduation, the defined criteria for replacement of restorations, the estimated past use of material in five-year increments and the records of 100 consecutively placed restorations. The materials used include composite (52.7%), amalgam (29.2%), glass ionomer (9.5%), resin-modified glass ionomer (7.1%) and other materials (1.4%). Although material selection was independent of the clinician's gender, female patients received more composite and fewer amalgam restorations than their male counterparts. Reasons for placing restorations comprised replacement of failed restorations (47.2%), primary caries (45.3%) and non-carious defects (7.5%). Secondary caries was the main reason for replacement for all types of restorations. Chi square analysis related to the dependence between the reasons for replacement and clinician's experience showed that more experienced clinicians recorded a lower frequency of secondary caries than less experienced ones (p<0.0001), while the diagnoses of discoloration and fracture of restorations increased with the clinicians' experience (p<0.0001).

Radiographic signs of bone destruction in the arthritic temporomandibular joint with special reference to markers of disease activity. A longitudinal study.

OBJECTIVE: To investigate the progression of radiographic changes of the temporomandibular joint (TMJ) with reference to plasma levels of interleukin-1beta (IL-1beta), C-reactive protein (CRP) and disease duration. METHODS: Twenty-one patients with chronic inflammatory joint disease and TMJ involvement were included. Individualized tomography of the TMJ was performed twice with an interval of at least 12 months. Blood samples were analysed for IL-1beta and CRP. RESULTS: Significant progression of the overall grade of radiographic changes occurred during the observation period, whereas erosions showed great interindividual variability. Progression of TMJ bone loss was correlated to raised levels of CRP and, in patients with a diagnosis of rheumatoid arthritis, or with shorter duration, also to plasma IL-1beta. CONCLUSION: Progression of overall grade of radiographic changes in the TMJ occurs in patients with chronic inflammatory joint disease. Raised levels of serum CRP are associated with progression of TMJ bone loss.

A 10-year prospective study of tobacco smoking and periodontal health.

BACKGROUND: To date only a few studies have evaluated the long-term influence of smoking and smoking cessation on periodontal health. The present study, therefore, was undertaken with the aim to prospectively investigate the influence of smoking exposure over time on the periodontal health condition in a targeted population before and after a follow-up interval of 10 years. METHODS: The primary study base consisted of a population of occupational musicians that was investigated the first time in 1982 and scheduled for reinvestigation in 1992 and 2002. The 1992 investigation included 101 individuals from the baseline study constituting a prospective cohort including 16 smokers, who had continued to smoke throughout the entire length of the 10-year period; 28 former smokers who had ceased smoking an average of approximately 9 years before the commencement of the baseline study; 40 non-smokers, who denied ever having smoked tobacco; and 17 individuals whose smoking pattern changed or for whom incomplete data were available. The clinical and radiographic variables used for the assessment of the periodontal health condition of the individual were frequency of periodontally diseased sites (probing depth > or =4 mm), gingival bleeding (%), and periodontal bone height (%). The oral hygiene standard was evaluated by means of a standard plaque index. RESULTS: The changes over the 10 years with respect to frequency of diseased sites indicated an increased frequency in continuous smokers versus decreased frequencies in former smokers and non-smokers. Controlling for age and frequency of diseased sites at baseline, the 10-year change was significantly associated with smoking (P <0.001). The differences between current smokers and non-smokers, and between current and former smokers, respectively, were statistically significant (P<0.001). Moreover, the 10-year change increased significantly with increasing smoking exposure controlling for age (P= 0.01). In terms of periodontal bone height, the 10-year changes implied statistically significant reductions within current as well as former smokers (P <0.001 and P <0.05, respectively), but not within non-smokers. The overall change was significantly associated with smoking controlling for age and bone height level at baseline (P<0.01), including statistically significant differences between current smokers and non-smokers and between current and former smokers, respectively (P<0.05). Moreover, the 10-year bone height reduction increased significantly with increasing smoking exposure controlling for age (P <0.05). With regard to gingival bleeding, the 10-year differences between smoking groups were not statistically significant. Plaque index remained low throughout in all smoking groups at an overall average level of about 0.8. CONCLUSIONS: The results suggest that periodontal health is compromised by chronic smoking as evidenced by an increase of periodontally diseased sites concomitant with loss of periodontal bone height, as compared to non-smokers whose periodontal health condition remained unaltered throughout the 10-year period of investigation. The periodontal health condition in former smokers, similar to that of non-smokers, remained stable, suggesting that smoking cessation is beneficial to periodontal health.

Exposure to tobacco smoking and periodontal health.

BACKGROUND: The influence of smoking behavior on the periodontal health condition was clinically and radiographically studied in 257 dentally aware adults in the age range 20-69 years, including 50 current smokers, 61 former smokers and 133 non-smokers. AIMS: The clinical variables to be investigated were frequency of diseased sites > or =4 mm, frequency of gingival bleeding sites and plaque index. In addition, the periodontal bone height was radiographically assessed as a % of the dental root length. METHODS: All variables were based on full-mouth examinations including all teeth and periodontia. RESULTS: The observations indicated an inferior periodontal health condition associated with smoking. This was evidenced by a significantly greater frequency of diseased sites and a significantly greater reduction of periodontal bone height in current smokers as compared to non-smokers. The condition of former smokers was intermediate between current smokers and non-smokers, suggesting that former smokers who have quit smoking have a better periodontal health condition than current smokers, although worse than that of non-smokers. The finding that former smokers exhibited less disease than current smokers suggests that smoking cessation may be beneficial and mitigate the untoward effects inflicted by smoking, allowing a normalization towards non-smoker conditions. Heavy exposure was consistently associated with more severe a condition than light exposure, suggesting that the relationship between smoking exposure and periodontal morbidity is dose-dependent. CONCLUSIONS: Altogether, the present observations identify a negative impact from smoking on periodontal health and provide further evidence that tobacco smoking is an avoidable risk for periodontal disease.

Periodontal bone height in professional musicians. Cross-sectional and longitudinal aspects.

Cross-sectional and longitudinal studies of the periodontal bone height were performed on professional musicians playing wind and non-wind instruments. The cross-sectional study population included 244 occupational musicians (186 men and 58 women aged 20-69 years) from three Swedish national orchestras. Eighty-seven were wind instrument musicians. Radiographic full-mouth surveys were performed and the periodontal bone height was measured with a computerized method and expressed as a percentage of the root length. The mean periodontal bone height was 83.4% for the musicians playing wind instruments and 83.6% for those playing non-wind instruments. There was no statistically significant difference in periodontal bone height between the two instrumentalist categories. In addition, the bone height quotients of anterior to posterior teeth were analyzed but no significant differences were found between wind and non-wind instrumentalists. A longitudinal cohort including 92 musicians who had been examined in a corresponding study 10 years earlier was studied. The overall loss of the periodontal bone height over the 10-year period was small, but only wind instrumentalists of the 50-69 year age group exhibited a statistically significant reduction over time. There was no statistically significant difference between musicians as regards instrument played. It is concluded from the cross-sectional and 10-year longitudinal observations that the playing of wind instruments is unlikely to affect periodontal bone height.

Noncontusive segmental spinal cord injury using radiofrequency current.

OBJECTIVE: To develop a nondisruptive model for the study of spinal cord injury. METHODS: A 2-MHz radiofrequency heating chamber was mounted over the rat T13-L1 vertebral column via a short dorsal incision. Epidural temperature at chamber level was monitored via a small proximal laminotomy. Forty-three rats were studied using time-temperature heating regimens from 45 to 48.5 degrees C and 4 to 15 minutes. A blinded numerical hind limb impairment score (Neurologic Impairment Score) was determined at intervals up to 2 weeks after injury. Segmental spinal cord blood flow was measured using [14C]butanol tissue uptake in injured and control rats. RESULTS: Above the injury threshold, increasing the time-temperature regimens was associated with a progressively worse Neurologic Impairment Score (r = 0.73-0.87 up to 24 hours after injury). Cord blood flow was unchanged at 2 hours but was 44% depressed at the injury level 6 hours after injury (p < 0.01). Histologically, injury extended minimally beyond the injured segment. Vascular thrombosis was not seen. CONCLUSION: This comparatively noninvasive model does not mechanically disrupt cord components and results in progressive neurologic impairment that correlates with the time-temperature regimen used for injury. It should be useful in identifying secondary phenomena that worsen functional status after cord trauma.

Interleukin-1beta in plasma and synovial fluid in relation to radiographic changes in arthritic temporomandibular joints.

The aim of this study was to investigate the level of the cytokine IL-1beta in plasma and temporomandibular joint (TMJ) synovial fluid of patients with arthropathies, and to study the relation between IL-1beta levels of synovial fluid and plasma as well as radiographic changes of the TMJ. 31 patients with general disease, 14 with rheumatoid arthritis (RA) and 17 with various arthritides were included in the study. Synovial fluid and blood samples were collected, and an individualized tomography of the TMJ was performed. Detectable levels of IL-1beta were found in 5 out of 39 synovial fluids and in 10 out of 27 plasma samples. The presence of IL-1beta in both plasma and synovial fluid was more frequent in RA patients than in the non-RA group. The extension of radiographic erosion was significantly greater in joints with IL-1beta than in those without. Both the extension of erosion and grade of radiographic changes of the TMJ were greater in patients with detectable IL-1beta level of plasma than in patients without. Our study indicates that presence of IL-1beta in plasma and synovial fluid is related to radiographic changes of the TMJ.

Minimum periodontal bone loss in dentally-aware adults. A 10-year prospective study.

A prospective study was performed on periodontal bone height changes over 10 years in dentally aware subjects. 94 subjects, aged 20-60 year, were radiographically examined by means of full mouth surveys at baseline in 1982 and 10 years later. The periodontal bone height evaluated by means of a computerized method was expressed as % of the root length. The mean of all measurements in the individual constituted the bone height value. The mean (SEM) periodontal bone height was 82.8% (0.64) at baseline and 82.0% (0.61) at follow-up. Although small, the periodontal bone height reduction over the 10 year period was statistically significant (p < 0.05). The reduction in periodontal bone height over time ranged from 0.4% (0.87) for subjects aged 30-39 years to 1.3% (0.80) for subjects aged 60-69 year. Only 15% of the subjects exhibited a bone loss > 5% and none > 10%. It is concluded that the rate of periodontal bone height reduction in dentally aware subjects is low. In the vast majority of these subjects, the 10 year bone loss may be considered clinically negligible.

Pain, tenderness, mandibular mobility, and anterior open bite in relation to radiographic erosions in temporomandibular joint disease.

The relationship between radiographic changes and clinical signs and symptoms of the temporomandibular joint (TMJ) was investigated in 39 patients with joint diseases. Radiographic erosions were found in 33% of the TMJ joints, and overall frequency of radiographic changes including remodeling was 47%. Fifty-four percent of the patients had an anterior open bite (AOB). The AOB showed statistically significant correlation to the extension of erosion of the TMJ. Pain expressed by means of a visual analog scale, tenderness to palpation of the TMJ, and pressure pain threshold showed no significant correlation to erosion, but mandibular mobility showed significant negative correlation to erosive changes. In conclusion, AOB is correlated with erosive radiographic changes in this patient group. However, the degree of local pain and tenderness showed no correlation to radiographic changes.

Radiographic evaluation of mandibular posterior implant sites: correlation between panoramic and tomographic determinations.

The purpose of the present study was to compare bone height determinations of implant sites by different radiographic techniques. Available bone height was measured in regions posterior to the mental foramen on panoramic radiographs, and on tomographs where the faciolingual dimension was at least 5mm. The bone heights were recorded at 401 edentulous and dentate sites in 100 patients. The overall mean bone height (m +/- SD) was 11.25 +/- 3.29 mm on panoramic radiographs and 8.81 +/- 3.38 mm on tomographs. The correlation between the two radiographic techniques ranged from 0.36 to 0.91 if the material was stratified according to factors such as height of available bone, age, gender and the presence of teeth. Gender was significantly correlated to panoramic and tomographic measurements in all regions. However, the precision of predicted tomographic measurements by using a linear regression model was not significantly increased by including gender as an explanatory variable. For evaluation of available bone height in mandibular regions posterior to the mental foramen, tomography is recommended for all prospective implant sites.

Reconstruction of the resorbed edentulous maxilla using autogenous rib grafts and osseointegrated implants.

14 patients with severely resorbed edentulous maxillae underwent reconstruction by the use of autogenous rib graft on-lays and osseointegrated Brånemark System implants in a one-stage procedure. 75 implants were installed. 16 (21.3%) failed to osseointegrate at the abutment connection. After a mean observation period of 5.2 years, 55 (73.3%) of the original implants were osseointegrated. 10 supplementary implants were inserted in 3 patients. At the end of the observation periods, 2 patients had overdentures and 12 had fixed prostheses. The mean marginal bone loss was 2.13 mm (SD 0.47 mm) the 1st year after grafting, and 2.92 mm (SD 1.27 mm) at the end of the follow-up periods. Long-term follow-up did not show any persistent donor site discomfort. The results indicate that this technique is a conceivable alternative for patients with severe maxillary resorption.

Effects of fixed anterior biteplane therapy--a radiographic study.

Orthodontic treatment of eight overbite cases with a maxillary fixed lingual arch appliance with anterior biteplane involved a reduction in overbite of 4 to 7 mm between the upper and the lower front teeth and a first molar separation of 2 to 4 mm. After a treatment period of 3.5 to 5 months, occlusal contact between the upper and the lower molars was established. The appliance was then removed, and permanent overbite reduction was secured with an edgewise appliance. With the subtraction technique, 15 temporomandibular joints were radiographically investigated in the retruded position for change of condylar position on the glenoid fossa before and directly after insertion of the appliance, as well as after achieved molar contact. All condyles changed position directly after the bite opening, indicating that pure rotation did not occur. The direction of movement varied not only between subjects but also between the two condyles of each subject. With one exception, none or very small further positional changes occurred during treatment. No imaged signs of hard structure remodeling were observed. It may be concluded that other factors than change of condylar position must be responsible for the therapeutic effect of the bite-opening appliance that has been demonstrated in an earlier study.

Periodontal bone loss of teeth with metal posts. A radiographic study.

Periodontal bone loss was compared in teeth with metal posts and contralateral teeth without metal posts by means of intraoral radiographs. 250 subjects with a high standard of dental awareness and a great number of teeth retained were included in the study. The periodontal bone loss was calculated from the ratio of the distance from bone margin to apex (bone height) and the distance from crown tip to apex (tooth length). Intra-individual differences between experimental and control teeth were statistically analyzed with the Student paired t-test. 96 subjects (38%) had > or = 1 teeth with root posts. In all, 172 teeth with posts were found, i.e., on average 1.8 teeth per subject. The means +/- SEM of the ratio bone height to tooth length in experimental and control teeth were 0.52 +/- 0.007 and 0.56 +/- 0.006, respectively. The difference was statistically highly significant (P < 0.001). Statistically significant differences were found for incisors, premolars and molars. Regression analysis indicated more severe bone loss for teeth with longer posts. The results suggest that the periodontal bone support of teeth with metal posts is inferior to that of teeth without metal posts.

Mandibular single crystal sapphire implants: changes in crestal bone levels over three years.

A total of 190 single crystal sapphire implants, 85 short (4S9S) and 105 long (4S9L), were monitored with panoramic and intraoral radiographs for 3 years. The implants were used as abutments for overdentures in edentulous mandibles in 51 patients. Within the first year, 2 patients lost one implant each due to pain and lack of osseointegration. Neither was replaced and the superstructures remained stable. At baseline registration, i.e., immediately after the prosthetic installation, the bone height relative to the length of the implant was calculated. The mean bone implant score (BIS) was 63.55 +/- 1.34% (mean +/- SE). BIS decreased during the first year 62.18 +/- 1.51%. At the 2- and 3-year recordings, the mean BIS were 61.81 +/- 1.58% and 61.73 +/- 1.63%, respectively. There were no statistically significant differences in BIS changes over the 3-year period or between men and women. The decrease in mean BIS was greater for implants in the premolar region than in the incisor region and for short implants than for long implants.

The hinge axis concept: a radiographic study of its relevance.

The "hinge axis concept" maintains that the mandible moves around a transverse horizontal axis through both condyles. Since it was introduced in the 1920s it has had a profound impact on clinical dental practices all over the world. By use of the radiographic subtraction technique, we demonstrated that an increase in the occlusal vertical dimension of 4 to 7 mm in the retruded position resulted in a small positional change (range 0.31 to 1.84 mm) in an unpredictable direction. Pure rotation did not occur; however, the condylar displacement is probably of minor clinical importance in prosthodontic restoration.

Panoramic and tomographic dimensional determinations for maxillary osseointegrated implants. Comparison of the morphologic information potential of two and three dimensional radiographic systems.

Accurate information on available bone volume is of decisive importance in dental implantology. The purpose of the present investigation was to examine the correlation between maxillary alveolar bone height measured on panoramic radiographs and on tomographic radiographs with a facio-lingual dimension of at least 5 mm. The alveolar bone height was recorded in 683 edentulous and dentate regions in 100 patients. The mean bone height (m +/- SD) in panoramic radiography for all regions was 11.90 +/- 3.60 mm and in tomography 8.20 +/- 4.33 mm. The differences in bone height recorded by the two techniques were greater in edentulous regions than in dentate regions, and the differences increased in regions where the available bone height was small. For preimplant assessment of available bone height in the maxilla, tomography is recommended for all regions intended for implants.

Evaluation of root resorption in relation to two orthodontic treatment regimes. A clinical experimental study.

The aim of the investigation was to evaluate the effect of a treatment pause on teeth in which apical root resorption was discovered after an initial treatment period of 6 months with fixed appliance. Forty patients with initial apical root resorption in 62 upper incisors were included in the study. In 20 patients treatment continued according to the original plan and in 20 patients active treatment was interrupted during a pause of 2-3 months. After the pause active treatment was resumed. Assessment of apical root resorption was performed on standardized radiographs taken with individual film holders. The amount of root resorption was significantly less in patients treated with a pause than in those treated without interruption.

Periodontal condition of epileptic adults treated long-term with phenytoin or carbamazepine.

The periodontal condition of 40 adult epileptic subjects (mean age 51 years) receiving long-term therapy (mean 18 years) with phenytoin (PHT) or carbamazepine (CBZ) was studied. The subjects completed a questionnaire and underwent clinical and radiologic examination. Patients receiving PHT exhibited the same level of alveolar bone loss as those receiving CBZ. Patients receiving PHT exhibited more units with gingival overgrowth, reflected by the significantly higher number of gingival units with increased probing depth (p < 0.05). The results indicate that long-term PHT does not result in increased risk for alveolar bone loss as compared with CBZ.

Methylprednisolone treatment of experimental spinal cord injury.

UNLABELLED: Lipid peroxidation has been identified as a deleterious consequence of contusive spinal cord trauma and of thermal injury. The L3-L6 spinal cord segment was thermally injured using a radiofrequency heating chamber mounted on the vertebral column of anesthetized rats. Hind limb function was assessed 2 hours later. A bolus of methylprednisolone (MP, 30 mg/kg) was then given intravenously, followed by 5.4 mg/kg/hr MP for 6 or 24 hours. Cord water content and regional spinal cord blood flow (RSCBF, 14C-butanol distribution) were measured at seven cord levels after function had been reassessed following treatment. Untreated rats were given vehicle. The study was randomized and blinded. RESULTS: Edema in heated segments was progressive over 24 hours, but was the same in treated vs untreated rats. RSCBF in heated segments was the same in treated vs uninjured controls at 6 and 24 hours. In untreated rats, RSCBF in the heated segment was elevated by 30% at 6 hours, but was the same as uninjured control by 24 hours. In the unheated segments of untreated rats, RSCBF was elevated at 24 hours. At 24 hours, RSCBF was lower in treated vs untreated rats at all levels, including the heated one. Limb function deteriorated equivalently in both groups. CONCLUSION: MP obviated the early rise in RSCBF in heated segments and the elevations in RSCBF in uninjured segments, but had no effect on cord edema or on limb function.