Biomedical subjects

K A Hiller

Publications and source records attributed to K A Hiller.

At least 19 recordsLinked to original sources

PubMed2003

Influence of interleukin-1 gene polymorphism on periodontal regeneration in intrabony defects.

The aim of this controlled retrospective study was to evaluate the influence of an IL-1 gene polymorphism on the clinical and radiographic healing outcomes of GTR therapy. The study included 47 adult periodontitis patients with 94 deep intrabony defects treated by GTR using different membrane materials. The following clinical parameters were recorded at baseline and 12 months after surgery: papillary bleeding index (PBI), gingival recession (REC), probing pocket depth (PPD), clinical attachment level (CAL), and the vertical relative attachment gain (V-rAG). Bone changes in the defect regions due to GTR therapy were quantitatively evaluated using digital subtraction radiography (DSR). Polymorphisms of the IL-1A gene at position - 889 and of the IL-1B gene at position + 3953 were analyzed by PCR. Statistical analysis was performed using the Mann-Whitney-U and the Wilcoxon-Signed-Rank tests (alpha = 0.05). The study comprised 19 IL-1 genotype positive (IL-1 +) patients and 28 IL-1 genotype negative (IL-1 -) patients. Twelve months after GTR therapy, both patient groups revealed statistically significant PPD reductions and CAL gain [median (25/75% percentiles)]: Delta PPD [IL-1 + : 4.0 (2.5/5.0) mm; IL-1-: 3.8 (3.0/4.9) mm], Delta CAL [IL-1 + : 3.5 (3.0/4.8) mm; IL-1 -: 3.0 (1, 2/4, 5) mm]. V-rAG amounted to 60.0 (47.7/78.6)% in IL-1 + patients and 53.1 (43.4/81.9)% in IL-1 - patients. Both patient groups showed significant bone density gain in 40% (IL-1 +) and 43.6% (IL-1 -) of the initial defect area due to GTR. Neither the clinical nor the radiographic healing parameters revealed any statistically significant differences in the GTR healing outcome between IL-1 + and IL-1 - patients. In conclusion, these 12-month findings indicate that the IL-1 gene polymorphism has no influence on the clinical and radiographic regeneration results following GTR therapy.

Adult↗

PubMed2001

Clinical evaluation of packable composite resins in Class-II restorations.

This study investigated the clinical performance of two packable composite resins in Class-II restorations. One hundred and four Class-II restorations were placed in 52 patients by five dentists (four in dental practices and one in a university clinic) in a controlled prospective multicentre clinical trial. Each patient received one Definite/Etch & Prime 3.0 (D-EP) and one Solitaire/Solid Bond (S-SB) restoration, which were examined clinically according to modified USPHS-criteria after 1 week (baseline) and after 1 year. Statistical analysis was performed using the Wilcoxon rank sum test and the error rates method. The significance level was set to 0.05. At baseline both materials performed equally according to the evaluated criteria. After 1 year D-EP showed significantly worse marginal adaptation compared to S-SB. Both materials displayed significant deterioration for the criteria marginal adaptation, marginal discolouration, approximal contact, and fracture of restoration after 1 year compared to baseline. With a failure rate of 9.6% after 1 year, D-EP did not fulfill ADA acceptance criteria for restorative materials. It is proposed that at least 1-year data of clinical testing should be available before a new material is broadly marketed.

Adolescent↗

PubMed2001

Curing efficiency of different polymerization methods through ceramic restorations.

The aim of this in vitro study was to examine the curing efficiency of three different polymerization methods through ceramic restorations by determination of the depth of cure and the universal hardness of a composite resin luting material. Therefore, 36 ceramic specimens [Empress 2 (Ivoclar), color 300, diameter 4 mm, height 2 mm] were prepared and inserted in steel molds (diameter 4 mm, height 6 mm) using a composite resin luting material [Variolink II (Vivadent)] with and without catalyst. The polymerization through six specimens of each group was done conventionally (40 s), by softstart polymerization (40 s), or by plasma arc curing (10 s). Depth of cure under the ceramic specimens was assessed according to ISO 4049. Additionally, universal hardness was determined at 0.5 and 1.0 mm from the ceramic using a universal testing machine (Zwick 14040). Curing without a catalyst, using conventional and softstart polymerization, resulted in greater hardness in both layers, compared to plasma arc curing. The use of a catalyst always produced a greater hardness and depth of cure with all polymerization methods. Depth of cure was always greater using conventional polymerization and softstart polymerization, compared to plasma arc curing. The curing efficiency of plasma arc curing through ceramic was lower compared to conventional and softstart-polymerization.

Dental Porcelain↗

PubMed2001

Patients with local adverse effects from dental alloys: frequency, complaints, symptoms, allergy.

Data on the prevalence of adverse effects from dental cast alloys and on the characteristics of the related patient groups are scarce. Therefore, the aim of the present study was to investigate patients in a defined part of Germany attributing oral complaints or symptoms to dental cast alloys. All dentists in the area of Eastern Bavaria (with 1 million inhabitants) were asked to send corresponding patients to our department during a 3-year period. Out of this collection, patients with complaints or symptoms in the oral cavity were recruited and characterized with regard to number, age and sex distribution, type of subjective complaints and objective intraoral symptoms, and allergy status based on an alloy analysis. Patients reporting to our department with suspected local adverse effects from dental cast alloys represented 0.01% of the population. Thirty-four percent of the patients were 50-59 years old, with females prevailing (76%). A great variety of subjective complaints was reported, which mainly resembles those reported by patients with adverse effects attributed to other dental materials like amalgam or denture base materials. The main objective intraoral symptoms were gingivitis, anomalies of the tongue (lingua plicata, lingua geographica), discoloration of the gingiva, redness of the palate or tongue and lichenoid reactions of the oral mucosa. In not more than 10% of the patients, allergy was diagnosed as contributing to the complaints or symptoms.

Adult↗

PubMed2001

Permeability characteristics of bovine and human dentin under different pretreatment conditions.

In order to use bovine dentin instead of human dentin for in vitro adhesion and cytotoxicity tests the permeability characteristics of human and bovine dentin should be similar. In the present study hydraulic conductance (Lp) and diffusional water flux (J5) of human and bovine dentin slices were compared. The permeability experiments were performed in a split chamber using tritiated water in physiological saline. Lp and Js of bovine dentin were 0.7- to 2.4-fold and 1.1- to 3.5-fold that of human dentin (not statistically significant). For human and bovine dentin Lp and Js increased with etching and showed an inverse linear relationship (r > or = 0.7) with dentin thickness. The variability of bovine data was low (perfusion = 30%, diffusion = 22%) and about half that of the human data. In conclusion bovine dentin near the cementoenamel junction seems to be a suitable alternative for coronal human dentin for in vitro tests with respect to transdentinal permeability characteristics.

Acid Etching, Dental↗

PubMed2000

Retrospective clinical study and survival analysis on partial ceramic crowns: results up to 7 years.

The purpose of the present study was to determine retrospectively the clinical performance of 42 all-ceramic partial crowns (PCCs) placed during the past 7 years. All patients (n = 25) with partial ceramic crowns (n = 49) placed by one experienced dentist between 1992 and 1999 were asked to take part in a clinical study, and 22 patients with 42 restorations agreed to do so. All partial ceramic crowns studied were fabricated using the IPS-Empress I all-ceramic system (Vivadent). The following luting composites were used for placing the restorations: 20 (47.6%) Variolink high viscosity (Vivadent), 3 (7.1%) Variolink ultra (Vivadent), 17 (40.5%) Dual Zement (Vivadent), and 2 (4.8%) Compolute (Espe). The partial ceramic crowns were examined clinically using the modified USPHS criteria. Of the 42 restorations, 40 (95.2%) were still in function without any need of replacement. One restoration (2.4%) had failed before starting the clinical study, and another one (2.4%) fractured during the study. Twenty-eight (66.7%) of the partial ceramic crowns evaluated were rated Alpha with respect to marginal adaptation. Twelve (28.6%) restorations were rated Bravo, no Charlie ratings were found and 2 (4.7%) restorations were rated Delta. The Kaplan-Meier analysis was used to calculate the survival rate. The probability of survival (95% confidence interval) for 7 years was 81% (66-96%). These data indicate that partial ceramic crowns may provide successful esthetic restorations in posterior teeth.

Adult↗

PubMed2000

Release of prostaglandin E2, IL-6 and IL-8 from human oral epithelial culture models after exposure to compounds of dental materials.

A three-dimensional human tissue model based on TR146 cells isolated from a squamous cell carcinoma of the buccal mucosa was used to test for the release of the proinflammatory molecules prostaglandin E2 (PGE2), interleukin 6 (IL-6), and interleukin 8 (IL-8) after exposure to nickel chloride (NiCl2), cobalt chloride (COCl2), palladium chloride (PdCl2), and triethylene glycol dimethacrylate (TEGDMA). These compounds have documented adverse biological effects in vitro. The release of PGE2 from the tissue culture models was inversely correlated with cell viability (MTT assay). Toxic concentrations of NiCl2 and CoCl2 induced the release of PGE2 by factors of about 200-300 compared to controls, but PdCl2 which was nontoxic enhanced PGE2 levels about 10-fold. TEGDMA, however, did not stimulate PGE2 release. None or weakly toxic concentrations of Ni and Co chloride induced IL-6 and IL-8 release by a factor of 5-10 compared to controls. The amounts of IL-6 were induced 25- to 30-fold by PdCl2 under physiological conditions, and IL-8 levels were also slightly enhanced. Nontoxic TEGDMA concentrations induced IL-6 levels 5-fold, but IL-8 amounts increased only slightly. We conclude that a steep rise of PGE2 is closely associated with cytotoxicity. On the other hand, the specific induction of IL-6 occurs at much lower concentrations. Therefore, the measurement of this cytokine may be included as another parameter in evaluating the biological activity of dental materials under nontoxic experimental conditions in vitro.

Biocompatible Materials↗

PubMed1999

Clinical performance of polyacid-modified resin restorations using "softstart-polymerization".

This study investigated the influence of "softstart-polymerization" on the clinical performance and marginal integrity of polyacid-modified resin restorations (PMR) in class V cavities. Eighty PMR restorations were placed in 20 patients [40 Dyract (DY); 40 Hytac (HY)] with (npat = 10) and without preparation (npat = 10). Restorations were light cured for 40 s either conventionally (CP) or with a lower light intensity for the first 10 s (SSP). Each patient received four restorations (DY-CP, DY-SSP, HY-CP, HY-SSP), which were examined clinically according to modified USPHS criteria, and by quantitative SEM-analysis after 7 days (baseline), 6 months and 1 year. Statistical analysis was performed using the Mann-Whitney-U test (P < or = 0.05) and error rates method. Clinically, no restoration showed recurrent caries or crevices. After 1 year, margins of 24-47% of the HY- and 36-53% of the DY-restorations were rated "Bravo". Marginal discoloration occurred in 20-37% in HY- and in 18-21% in DY-restorations. The error rates method revealed no significant differences between materials or between polymerization modes with and without preparation. Pairwise testing showed that without preparation, the marginal adaptation to dentin was significantly worse compared to enamel for HY with both polymerization modes, for DY with SSP. With preparation, no significant differences were found. Cavity preparation may have an influence on differences in marginal quality between enamel and dentin.

Compomers↗

PubMed1998

Retrospective clinical investigation and survival analysis on ceramic inlays and partial ceramic crowns: results up to 7 years.

This study retrospectively evaluated the clinical performance of 287 all-ceramic restorations placed during routine patient care in the University setting in the past 7 years. All patients (n = 106) with ceramic inlays or partial ceramic crowns (PCC), placed during 1988-1994 (n = 327) by five experienced dentists were asked to take part in a clinical investigation, and 92 patients with 287 restorations (232 inlays, 55 PCC) agreed to do so. The following ceramics were used: 44 (15.3%) Dicor (Dentsply), 126 (43.9%) IPS-Empress (Ivoclar), 82 (28.7%) Mirage II, 33 (11.5%) Cerec-Vita-Mark 1 (Vita), and 2 (0.7%) Duceram LFC (Ducera) restorations. The restorations were placed using the following luting composites: 73 (25.4%) Dual Cure Luting Cement (Optec), 81 (28.3%) Variolink high viscosity (Ivoclar), 32 (11.1%) Microfill Pontic C (Kulzer), 51 (17.8%) Dual Zement (Ivoclar), 40 (13.9%) Dicor Light Activated Cement (Dentsply), and 10 (3.5%) Vita Cerec Duo Cement (Vita). Restorations were evaluated according to the modified USPHS criteria. Kaplan-Meier analysis was used to calculate the probability of survival. Of the 287 restorations 270 (94.2%) were still in function without any need of intervention. Fourteen restorations (4.8%) had failed before starting the clinical investigation, and in three a fracture was found during the investigation. These 17 failed restorations consisted of 14 PCC and 3 ceramic inlays. The results of the clinical investigation revealed 59.2% Alpha-ratings for marginal adaptation. Only one restored tooth showed recurrent caries. The probability of survival (95% confidence interval) for 7 years was 98% (97.99-98.01%) for ceramic inlays and 56% (46-66%) for PCC. Our findings show that ceramic inlays can be regarded as an acceptable alternative to cast gold restorations within the methodological limitations of the present study. For PCC further experience with more recent ceramics is warranted.

Adolescent↗

PubMed1998

Quantitative digital subtraction radiography for the determination of small changes in bone thickness: an in vitro study.

OBJECTIVE: The objective of this study was to determine the ability of quantitative digital subtraction radiography to detect small changes in bone thickness adjacent to tooth roots. STUDY DESIGN: A series of cortical or cancellous bone slices with a 50 microm-stepwise increasing thickness were attached to 4 porcine mandible sections covering buccal and interproximal "defect" regions. Standardized radiographs were quantitatively evaluated for radiographic density changes with the use of digital subtraction radiography. Furthermore, all radiographs were conventionally evaluated by 10 clinicians. The Wilcoxon signed-rank test and the Mann-Whitney U test were used for statistical analysis (alpha = 0.05). RESULTS: A high linear correlation was found between the actual thickness of bone slices and radiographic density changes (cortical bone: r2 = 0.89 to 0.99; cancellous bone r2 = 0.61 to 0.86, p < or = 0.001). A certain increase in bone thickness caused a 3 times higher increase in radiographic density for cortical bone than for cancellous bone (p < or = 0.05). The detection limits of digital subtraction radiography were 200 microm for cortical and 500 microm for cancellous bone, whereas the detection limits of conventional radiography were 600 microm and 2850 microm, respectively. CONCLUSIONS: This in vitro study demonstrated a very high correlation between the objective, quantitative assessment of subtle changes in alveolar bone by digital subtraction radiography and the true changes in bone thickness.

Absorptiometry, Photon↗

PubMed1998

GTR therapy of intrabony defects using 2 different bioresorbable membranes: 12-month results.

This prospective split-mouth study was designed to compare the clinical and radiographic healing results in intrabony periodontal defects 12 months after GTR therapy with 2 different bioresorbable barriers. The study comprised 25 healthy patients with one pair of contralaterally located intrabony defects with a probing pocket depth of > or = 6 mm and radiographic evidence of angular bone loss of > or = 4 mm. The 2 defects of each patient were randomized for treatment either with polylactic acid (PLA) membranes or with polyglactin-910 (PG-910) membranes. The patients received systemic doxycycline (100 mg/d) for 11 days postoperatively. One blinded examiner recorded the following clinical parameters using a pressure calibrated probe at baseline and after 12 months: papillary bleeding index (PBI), gingival recession (REC), probing pocket depth (PPD), and probing attachment level (PAL). The vertical relative attachment gain (V-rAG) was calculated as a % of the PAL gain related to the maximum possible attachment gain (expressed by the intraoperatively measured depth of the osseous defect). Geometrically standardized intraoral radiographs were quantitatively evaluated for bone changes (density, area) in the defect region using digital subtraction radiography (DSR). Clinical and radiographic data were statistically analyzed using the Wilcoxon-signed-rank test (alpha=0.05). Postoperative membrane exposures occurred in 9 PLA and 13 PG-910 treated sites. After 12 months of healing, both barrier types provided significant PPD reductions and PAL gain [median (25/75 percentile)]: deltaPPD [PLA: 3.0 (2.0/4.0) mm; PG-910: 3.0 (2.0/4.5) mm]; deltaPAL [PLA: 3.0 (2.5/4.0) mm; PG-910: 2.0 (1.0/4.0) mm]. V-rAG amounted to 60% in PLA sites and 54% in PG-910 sites. DSR revealed significant bone density gain after 12 months. 58.3% of the initial defect area in PLA sites and 54.0% of the initial defect area in PG-910 sites showed bone density gain. Neither clinical nor radiographic data revealed any significant difference between the 2 barrier types after 12 months. In conclusion, this 12-month study demonstrated that PLA and PG-910 membranes provided similar favorable regeneration results in deep intrabony periodontal defects.

Adult↗

PubMed1998

Accuracy of quantitative digital subtraction radiography for determining changes in calcium mass in mandibular bone: an in vitro study.

The aim of this in vitro study was to determine the accuracy of digital subtraction radiography (DSR) to detect small changes in calcium mass in alveolar bone adjacent to tooth roots. In each of 4 dried porcine mandible segments, one interproximal and one buccal "defect" region was defined adjacent to a premolar root. A series of cortical and cancellous bone slices with a 50 microns--stepwise increasing thickness (0-5000 microns) were attached to the mandible segments covering the respective "defect" region. Standardized radiographs were quantitatively assessed for density changes using DSR. After dissolving each bone slice in hydrochloric acid, its calcium concentration was photometrically determined. For each bone slice, the mean calcium mass covering a single pixel of the subtraction image was calculated. The Wilcoxon signed-rank test and the Mann-Whitney U-test were used for statistical analysis (alpha = 0.05). A strong linear correlation (r2 = 0.86-1.00; p < or = 0.001) was found between the thickness of the bone slices and their calcium mass. Cortical bone showed a 3.5 times higher mean calcium mass/pixel than cancellous bone. Furthermore, a strong linear correlation (r2 = 0.63-1.00; p < or = 0.001) was found between the mean calcium mass per image pixel and the radiographic density changes. Neither the bone type nor the "defect" localization had a significant influence on radiographic density changes caused by changes in calcium mass. A change in mean calcium mass per image pixel of 0.1-0.15 mg was necessary to be detected by DSR. In conclusion, this study revealed a high accuracy of DSR to detect small changes in calcium mass in alveolar cortical and cancellous bone.

Alveolar Bone Loss↗

PubMed1998

Developmental enamel defects in children with different fluoride supplementation--a follow-up study.

The intake of fluorides with water, food, dental fluoride preparations, or in particular fluoride supplements, such as NaF tablets, may lead to dental fluorosis. In the present study conducted in a nonfluoridated area in Germany, developmental enamel defects were examined using the Modified Developmental Defects of Enamel Index (Mod DDE Index), which subdivides enamel defects into the categories demarcated (Mod DDE score 1) and diffuse (Mod DDE score 2) opacities and hypoplasia (Mod DDE score 3). 158 children, between 8.5 and 10 years old, were assigned to three examination groups, defined by three different fluoride tablet programs. The children in all three examination groups, F1, F2, and F3, had received 0.25 mg F-/day up to the age of 2 years, F1 and F3 from birth on, F2 beginning with the 7th month of life. F1 and F2 received 0.5 mg F-/day during the 3rd and 0.75 mg F-/day during the 4th and 5th year of life. For F3, beginning with the 3rd year of life, no further recommendations were made. 158 sociodemographically matched children living in a neighboring town served as controls and did not take part in any structured fluoride supplementation program. The proportions of children with Mod DDE scores 1, 2, or 3 at least in one index tooth were significantly higher in the examination groups (40%) than in the control group (20%). Also, the proportions of children with Mod DDE score 2 at least in one index tooth were significantly higher in the examination groups (18%) than in the control group (8%). The proportions of children with Mod DDE score 1 at least in one index tooth were 25% in the examination groups and 17% in the control group. No Mod DDE score 3 was found. Not more than 5% of the children in each group had 50% of their teeth with Mod DDE score 1, 2, or 3. The proportions of teeth per child with Mod DDE score 2 were significantly higher in the examination group than in the control group. While uncontrolled variables cannot be excluded, the observed differences between the experimental and control groups may be attributed to the ingestion of fluoride tablets in the experimental group.

Age Factors↗

PubMed1997

Postoperative exposure of bioresorbable GTR membranes: effect on healing results.

The goal of this investigation was to evaluate the effect of postoperative exposure of two different bioresorbable membranes on the guided tissue regeneration (GTR) healing results compared to nonexposed sites. In each of 25 patients one pair of contralateral intrabony lesions was treated either with polylactic acid (PLA) or polyglactin 910 (PG-910) membranes. Postoperative exposure occurred in 9 PLA and 13 PG-910 sites. Standardized clinical [papillary bleeding index (PBI), gingival recession (REC), probing pocket depth (PPD), probing attachment level (PAL)] and radiographic examinations (digital subtraction radiography) were performed immediately before (baseline) and 6 and 12 months postoperatively (p.o.). Subgingival bacterial samples from surgical sites were evaluated by culture at baseline, 6 weeks, and 6 and 12 months p.o. Six months after surgery the changes (delta) of REC were significantly (P < or = 0.05) greater in exposed than in nonexposed sites, independently of the membrane material (median): exposed sites, delta REC = -1 mm; nonexposed sites, delta REC = 0.0 mm. However, 12 months p.o. no significant differences were found due to a decrease in the initial recessions in exposed sites. Although a higher percentage of exposed than nonexposed sites harbored periodontal pathogens 6 weeks p.o. at the gingiva-faced membrane surface, membrane exposure did not have a significant negative effect on delta PPD, delta PAL, or radiographic bone density changes 6 and 12 months p.o. Both membranes showed significant gains in PAL and bone density in both exposed and nonexposed sites. In conclusion, this study demonstrates that with consistent infection control the postoperative exposure of PLA and PG-910 membranes has no significant negative effect on the regeneration outcome, although higher initial gingival recessions must be expected than in the nonexposed sites. However, in exposed sites plaque and infection control were clearly impeded by the rough, exposed membrane surfaces and by the initially negative gingival morphology.

Adult↗

PubMed1997

Clinical and quantitative marginal analysis of feldspathic ceramic inlays at 4 years.

The aim of this clinical study was to evaluate feldspathic ceramic inlays both by clinical criteria and quantitative margin analysis in continuation of an earlier, identically conducted 2-year study. Fifty feldspathic ceramic inlays were adhesively luted in Class II preparations with all margins located in enamel. The inlays were evaluated clinically according to modified USPHS criteria after 3 and 4 years. Quantitative margin analysis was performed with a scanning electron microscope (SEM). Clinically, the inlays showed no recurrent caries and no changes in colour, but superficial marginal discolouration (6%) was apparent after 4 years. Margins were perceptible clinically in 64% of the cases after 4 years. Quantitative margin analysis showed significantly more marginal gaps at the composite/ceramic interface than at the enamel/composite interface, There was neither a significant decrease in perfect margins nor a significant increase in marginal gaps and marginal imperfections at both interfaces between the third and fourth year. Clinically, the inlays performed very well up to 4 years. Clinical evaluation using an explorer only detected substance loss in the cementation gap. The SEM evaluation showed significantly higher changes in marginal qualities during the first 2-year interval of clinical service compared to the second 2-year interval following an exponential mathematical regularity. Quantitative margin analysis should be included in clinical long-term trials to detect early marginal deficiencies at the luting interfaces.

Aluminum Silicates↗

PubMed1997

SEM analysis of marginal expansion and gap formation in Class II composite restorations.

OBJECTIVES: Morphological changes in terms of marginal expansion have been observed at the dentin-composite interface of resin composite restorations with the scanning electron microscope (SEM), which could not be described with the criteria conventionally used for quantitative marginal analysis. The purpose of the present study was to elucidate the influence of marginal expansion upon marginal integrity and clarify the cause of these morphological changes. METHODS: A total of 22 extracted human molars were restored with Class II resin composite restorations, with and without the use of a dentin bonding agent. The cervical restoration margin was located below the cemento-enamel-junction (CEJ). The marginal adaptation at the dentin- and enamel-composite interfaces was evaluated and measured on replicas using quantitative SEM analysis after different storage periods. The chemical composition of the marginal expansion was determined qualitatively by EDX (Energy Dispersive X-Ray) analysis using original tooth samples. The results obtained from quantitative SEM analysis were statistically analyzed by applying the Mann-Whitney U-test and the error rates method. RESULTS: Significantly less marginal expansion occurred at the enamel interface than at the dentin-composite interface (p < or = 0.01). Within the dentin, less marginal expansion was observed with the use of a dentin bonding agent than without a dentin bonding agent (p < or = 0.05). At 1 y, a significant (p < or = 0.05) decrease in marginal expansion was observed in both groups. EDX analysis revealed that the chemical composition of the marginal expansion is comparable to the resin composite, since peaks for silicon, barium and ytterbium could be found at these sites. SIGNIFICANCE: In Class II resin composite restorations below the CEJ, partial disruption of the adhesive bond may occur initially when curing the restoration. Water sorption causes gap reduction by hygroscopic expansion, seen in the SEM as a volume increase. Thus, the observed morphological changes can be regarded as an early sign of insufficient adhesion between composite and dentin at sites where disruption of the bond occurred initially, whether or not a dentin bonding agent was used.

Acrylates↗

PubMed1997

Periodontal regeneration of intrabony defects with resorbable and non-resorbable membranes: 30-month results.

The aim of this prospective split-mouth-study was to compare the healing results in intrabony defects 12 and 30 months after placement of resorbable (polyglactin-910) and non-resorbable (e-PTFE) GTR-membranes. 11 healthy patients with 30 defects participated. 10 patients with 10 pairs of contralateral lesions, which were treated with both membrane types, were included in the split-mouth-design. Furthermore, in an additional group-design all 30 (16 polyglactin-910 and 14 e-PTFE) treated sites were evaluated. Clinical examinations (PBI, REC, PPD, PAL) and radiographic examinations were carried out under standardized conditions immediately before as well as 12 and 30 months after surgery. Additionally, for the assessment of the effectiveness of the 2 membranes by comparing the regeneration results of different defects, the vertical relative attachment gain (V-rAG) was calculated as a % of the PAL gain related to the maximum possible attachment gain (expressed by the baseline depth of the osseous defect intraoperatively measured). Digital subtraction radiography (DSR) was carried out for the quantitative assessment of bone density changes due to GTR. In the split-mouth-design, both types of membranes provided significant V-rAGs (median) after 12 months (polyglactin: 81.7%; e-PTFE: 100.0%) and after 30 months (polyglactin: 69.1%; e-PTFE: 83.8%) compared to baseline. In 90.0% of the polyglactin and e-PTFE sites, a probing attachment gain of at least 2 mm was maintained over the 30-month period. However, in 2 polyglactin treated sites, and 5 e-PTFE treated sites, a new attachment loss was found between 12 and 30 months. DSR showed bone density gain 12 and 30 months postsurgically. No statistically significant differences could be observed between the 2 membrane materials with regard to clinical and radiographic findings. This was confirmed when considering the total number of defects (group-design). In conclusion, based on this 30-month-study resorbable polyglactin membranes may be regarded as a useful alternative to the well established e-PTFE membranes for the treatment of intrabony defects.

Adult↗

PubMed1997

Resin-modified glass ionomer cements: fluoride release and influence on Streptococcus mutans growth.

The aims of the present study were to measure the fluoride release of 1 glass ionomer cement, 1 cermet, 3 resin-modified glass ionomer cements and 1 compomer, and to determine the influence of each material on bacterial growth. Test specimens were eluted in saline for 180 days. Every 2 days, the specimens were transferred into fresh saline and the fluoride content of the solution was measured. Furthermore, 48-h, 14-d, 90-d, and 180-d eluates were inoculated with Streptococcus mutans and bacterial growth was recorded nephelometrically. Fluoride release dropped significantly over time for each material with values between 6.2 (Ketac-Silver) and 29.3 (Photac-Fil) ppm after 48 h to values between 0.6 (Ketac-Silver) and 1.7 (Ketac-Fil, Vitremer) ppm after 180 days. Each material reduced bacterial growth at each time of examination, but the effect decreased significantly over time with a maximum growth of 71.7% (Ketac-Fil) to 85.6% (Ketac-Silver) after 48 h and 94.7 (Vitremer) to 99.0% (Ketac-Silver) after 180 days (growth control = 100%). Both Ketac-Silver and Dyract showed a significantly lower inhibiting effect on bacterial growth than the other materials. The tested materials showed a good correlation between fluoride release and influence on bacterial growth. However, both effects dropped dramatically over the 180-days period.

Cariostatic Agents↗