Comparatively few studies are available reporting at least 5 years of follow-up data of implant-s... more Comparatively few studies are available reporting at least 5 years of follow-up data of implant-supported single-tooth replacements. To evaluate prospectively the 5-year outcome of implant-supported single-tooth prosthetic restorations. Forty subjects (mean age 41 years), 23 males and 17 females, who required single-tooth prosthetic replacement for a missing tooth were recruited. A total of 45 self-tapping implants (Astra Tech ST-implants)--40 in the maxilla and five in the mandible--were installed in a two-stage procedure. Abutment connection was performed 3-6 months after implant installation. Clinical and radiographic examinations were performed at the completion of the prosthetic treatment and once a year during a 5-year follow-up period. The analysis of peri-implant bone level alteration was performed on subject and implant levels and by the use of analysis of variance and binary logistic regression. Three patients were lost during the 5 years of follow-up. One implant was lost after 2.5 years in function and another four implants could not be accounted for at the 5-year follow-up examination. The overall failure rate at 5 years was 2.6% (subject level) and 2.3% (implant level). The mean loss of marginal bone at the implants during the first year in function was 0.06 mm (SD 0.67) on the subject level and 0.02 mm (0.65) on the implant level. During the subsequent 4 years the annual change in peri-implant bone level amounted to -0.02 mm (0.22) on both subject and implant levels. Thus, the mean total bone level change over the 5-year interval was -0.14 mm (1.04) on subject level and -0.11 mm (1.00) on the implant level of analysis (p>0.05). The frequency of implants with a 5-year bone loss of > or =1 mm was 13%. Approximately 50% of the implants demonstrated no bone loss. The present clinical trial on single-tooth replacements with the Astra Tech implant system demonstrated that the bone loss during the first year of function as well as annually thereafter was small.
Purpose: The aims of this study were to assess changes in the microhardness and surface roughness... more Purpose: The aims of this study were to assess changes in the microhardness and surface roughness of a dual-cured composite resin cement after water storage for different periods of time. Materials and methods: Sixty specimens were divided into four groups comprising high- and low-viscosity cement specimens stored either dry or in water for 1 to 60 days. Microhardness and surface roughness measurements were made after 1, 7, and 60 days of storage. Results: It was found that that although interactions complicated the interpretation of the results, the water-stored samples had a significantly lower microhardness compared to the dry-stored specimens for every time interval. In addition, the high-viscosity specimens had a significantly higher microhardness compared to the low-viscosity specimens. An increased microhardness was found for all groups, except for the low-viscosity, water-stored specimens after 60 days of water storage, which was attributed to an effect of the chemical postcuring process. Although difficult to evaluate from a clinical point of view, the laser profilometry analysis revealed that a significantly increased surface roughness was found after water storage and increased storage time that was possibly caused by a deterioration of the resin-matrix surface. Conclusion: For the permanency of the interfacial luting material, a high microhardness value seems to be important.
Due to their inertness and unsurpassed aesthetic properties, ceramic materials are increasingly u... more Due to their inertness and unsurpassed aesthetic properties, ceramic materials are increasingly used as inlay materials. Based on a questionnaire, the frequency and character of complications related to ceramic inlay therapy were assessed and some important pitfalls and clinical relevant factors discussed. A majority of the dentists performed between 1 and 10 ceramic inlays per month using several different ceramic materials. As many as 85% of the dentists had observed complications in connection w^ith ceramic inlays. Most frequency reported was hypersensitivity of a transient nature (15%). The material revealed an overall inlay fracture frequency of 5%, but the individual variations were high. Tooth fracture, loss of retention and other complications such as secondary caries, endodontic envolvement, colour mismatch and a surface and edge deterioration occurred w^ith a varying but low^er frequency. Failure analysis revealed a large number of causative factors among w^hich cavity and inlay design, bonding procedures, selection of luting material and proper case selection were regarded as the most important. Due consideration to the strength of remaining tooth substance w^as found to be important in reducing the problem of hypersensitivity and the risk of tooth and inlay fracture.
In the present study we investigated the prevalence of self-reported hand eczema as well as subje... more In the present study we investigated the prevalence of self-reported hand eczema as well as subjective associations between skin symptoms and composite/bonding or other dental materials among Swedish dentists. A questionnaire on skin symptoms, atopy, occupational experience, and other background factors was sent to a random sample (n~3,500) of all dentists licenced since 1965. This group corresponds to about half of the country's occupationally active dentists. The response rate was 88%. The questionnaire had previously been validated against clinical dermatological examination of subjects reporting hand eczema. The prevalence of dry and rough skin on the hands was high (45%). Hand eczema during the previous 12 months was reported by 13.5%. Dry skin and hand eczema were more common among dentists than in two age-matched general population samples investigated using identical questions. The difference versus the general population was most pronounced (about twofold) among male dentists. A history of childhood eczema was the most important predictor for adult hand eczema, with a prevalence ratio of 2.4 compared to dentists without childhood eczema. Seven % reported skin symptoms when working with acrylic resins, and 15% had experienced rapid itching related to protective gloves.
By means of a questionnaire, clinical examination and force recordings, the relationships between... more By means of a questionnaire, clinical examination and force recordings, the relationships between self‐assessed masticatory ability, dental state and bite force were studied in 160 80‐year‐old persons, 74 men and 86 women. The subjects were in general satisfied with their masticatory ability and 70% had no problems, while 6% reported three or more problems with mastication. Half of the subjects were dentate without removable prostheses and almost one‐third had 20 or more natural teeth. The edentulous persons (about one‐fifth of all) reported more problems related to mastication than the other dentition groups. The maximal bite force varied much and exhibited a significant correlation to the number of remaining teeth and dental state. The self‐assessed masticatory ability was only weakly correlated with dental state and bite force. It was concluded that many subjects with few or no remaining teeth and/or removable dentures had only few complaints of impaired masticatory function and showed a good adaptation to an impaired dental status and small maximal bite force.
Objective: The aim of this study was to retrospectively analyze whether the inclusion of cantilev... more Objective: The aim of this study was to retrospectively analyze whether the inclusion of cantilever extensions increased the amount of marginal bone loss at free‐standing, implant‐supported, fixed partial dentures (FPDs) over a 5‐year period of functional loading.Material and Methods: The patient material comprised 45 periodontally treated, partially dentate patients with a total of 50 free‐standing FPDs supported by implants of the Astra Tech® System. Following FPD placement (baseline) the patients were enrolled in an individually designed supportive care program. A set of criteria was collected at baseline to characterize the FPDs. The primary outcome variable was change in peri‐implant bone level from the time of FPD placement to the 5‐year follow‐up examination. The comparison between FPDs with and without cantilevers was performed at three levels: FPD level, implant level, and surface level. Bivariate analysis was performed by the use of the Mann–Whitney U‐test and stepwise regression analysis was utilized to evaluate the potential influence of confounding factors on the change in peri‐implant bone level.Results: The overall mean marginal bone loss for the implant‐supported FPDs after 5 years in function was 0.4 mm (SD, 0.76). The bone level change at FPDs placed in the maxilla was significantly greater than that for FPDs in the mandible (0.6 versus 0.2 mm; p<0.05). No statistically significant differences were found with regard to peri‐implant bone level change over the 5 years between FPDs with and without cantilevers at any of the levels of comparisons. The multivariate analysis revealed that the variables jaw of treatment and smoking had a significant influence on peri‐implant bone level change on the FPD level, but not on the implant or surface levels. The model explained only 10% of the observed variance in the bone level change.Conclusion: The study failed to demonstrate that the presence of cantilever extensions in an FPD had an effect on peri‐implant bone loss.
Cytotoxic methacrylate monomers have been identified in aqueous extracts of freshly cured compome... more Cytotoxic methacrylate monomers have been identified in aqueous extracts of freshly cured compomers. Some of these compounds, including HEMA and TEGDMA, induce apoptosis and necrosis in vitro. The aim of the present study was to elucidate possible signaling pathways involved in apoptosis following exposure to HEMA or TEGDMA in a salivary gland cell line. The cells were exposed to various concentrations of HEMA or TEGDMA. ROS formation was determined by dichlorofluorescein assay. Phosphorylated MAP-kinases ERK1/2, p38 and JNK, as well as specific caspases were identified by Western blotting. Apoptosis was assayed by fluorescence microscopy. HEMA or TEGDMA exposure resulted in ROS formation and concentration-dependent apoptosis as well as phosphorylation of ERK. Phosphorylation of JNK and p38 was induced by HEMA. Selective inhibitors of ERK and JNK modified the apoptotic response after HEMA and TEGDMA exposure, whereas p38 inhibition modified the apoptotic response only after HEMA exposure. Vitamin C reduced HEMA-induced apoptosis. ROS formation and differential MAP kinase activation appear to be involved in the apoptotic response following exposure to HEMA and TEGDMA.
Objectives. Digital impressions are increasingly used and have the potential to avoid the problem... more Objectives. Digital impressions are increasingly used and have the potential to avoid the problem of inaccurate impressions. Only a few studies to verify the accuracy of digital impressions have been performed. The purpose of this study was to compare the marginal and internal fit of 3-unit tooth supported fixed dental prostheses (FDPs) fabricated from digital and conventional impressions. Methods. Ten FDPs were produced from digital impressions using the iTero system and 10 FDPs were produced using vinyl polysiloxane (VPS) impression material. A triple-scan protocol and CAD software were used for measuring and calculating discrepancies of the FDPs at 3 standard areas: mean internal discrepancy, absolute marginal gap, and cervical area discrepancy. The Mann-Whitney U test was used for analyzing the results. Results. For conventional and digital impressions, respectively, FDPs had an absolute marginal gap of 147 m and 142 m, cervical area discrepancy of 69 m and 44 m, and mean internal discrepancy of 117 m and 93 m. The differences were statistically significant in the cervical and internal areas (< 0.001). Significance. The results indicated that the digital impression technique is more exact and can generate 3-unit FDPs with a significantly closer fit compared to the VPS technique.
Dentistry usually is &amp;amp;#39;wet work&amp;amp;#39; with risk of damage to the skin b... more Dentistry usually is &amp;amp;#39;wet work&amp;amp;#39; with risk of damage to the skin barrier, and the hands may be exposed to skin irritants and contact-sensitizing substances used in dental materials or gloves. Airway irritants may also be present. This study assessed the consequences of work-related skin and airway symptoms among dentists in terms of contact with health authorities, sick leave, or changes in the professional career. A questionnaire on these factors was answered by more than 3000 Swedish dentists. Only 6% of the respondents had consulted a physician, although 22% had noted work-related skin symptoms. In 2% the skin symptoms had caused sick leave, and about 2% had reported their skin symptoms as an occupational disease. Two per cent had consulted a physician owing to work-related airway symptoms, which is a minor part of the 13% who had experienced such symptoms when in contact with dental materials. Twenty-five dentists (&amp;amp;lt;1%) had been on sick leave because of work-related airway symptoms. Only 1 dentists reported change of activities or occupation owing to work-related skin or airway symptoms, and in most cases these symptoms only contributed to their decision. In summary, whereas sick leave in dentists because of musculoskeletal problems may be common, the present study shows that this is not the case for work-related skin or airway symptoms, and such symptoms seldom affect the dentists&amp;amp;#39; professional career.
NIOM i endring NIOM har fått ny logo og har endret navn fra Nordisk institutt for odontologisk ma... more NIOM i endring NIOM har fått ny logo og har endret navn fra Nordisk institutt for odontologisk materialprøvning til Nordisk Institutt for Odontologiske Materialer. Artikkelen beskriver den modernisering som instituttet har gjennomgått.
Water sorption and solubility of six proprietary composite resin materials were assessed, and mon... more Water sorption and solubility of six proprietary composite resin materials were assessed, and monomers eluted from the organic matrix during water storage identi®ed. Water sorption and solubility tests were carried out with the following storage times: 4 h, 24 h and 7, 60 and 180 days. After storage, water sorption and solubility were determined. Eluted monomers were analysed by high performance liquid chromatography (HPLC). Correlation between the retention time of the registered peak and the reference peak was observed, and UV-spectra con®rmed the identity. The results showed an increase in water sorption until equilibrium for all materials with one exception. The solubility behaviour of the composite resin materials tested revealed variations, with both mass decrease and increase. The resin composition in¯uences the water sorption and solubility behaviour of composite resin materials. The HPLC analysis of eluted components revealed that triethyleneglycol dimethacrylate (TEGDMA) was the main monomer released. Maximal monomer concentration in the eluate was observed after 7 days. During the test period, quanti®able quantities of urethanedimethacrylate (UEDMA) monomer were observed, whereas 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)-phenyl]propane (Bis-GMA) was only found in detectable quantities. No detectable quantities of bisphenol-A were observed during the test period.
Purpose: The aim of this in vitro study was to evaluate the load resistance in a conical implant ... more Purpose: The aim of this in vitro study was to evaluate the load resistance in a conical implant system by comparing combinations of 2 different abutment head angles and 3 different retaining screw materials. Materials and methods: The retaining screw materials (titanium alloy, gold alloy, and commercially pure titanium) were tested with abutment-head angles of 20 degrees and 45 degrees. Six groups of 10 specimens each were prepared. An oblique (30-degree) compression test was performed in a Lloyd LRX universal testing machine with the abutment attached to a superstructure with a retaining screw. All specimens were loaded until fracture or permanent deformation occurred. The results were evaluated statistically with Wilcoxon signed rank test for variance distribution (P < .05 considered significant). Results: There were statistically significant differences in load resistance between 20-degree and 45-degree abutments. The titanium screws (titanium alloy and commercially pure) in the 45-degree abutment group had almost equal mean values, while the gold alloy had a significantly lower value. In the 20-degree abutment group, significantly higher values were found with commercially pure titanium compared to titanium alloy and gold alloy, but the difference between the values for the gold and titanium alloys was not significant. Discussion: The angulation of the abutment head played the most significant role in determining the amount of load withstood, but the material used for the screw was also relevant. Conclusion: A 45-degree abutment can be combined with a retaining screw of any of these materials to create a functional implant system. The test also substantiated that, irrespective of the retaining-screw material, a 20-degree abutment could resist loading forces of at least 900 N.
Objective: To compare two home-based over-the-counter (OTC) bleaching tray products with similar ... more Objective: To compare two home-based over-the-counter (OTC) bleaching tray products with similar hydrogen peroxide (HP) concentrations with respect to tooth lightening efficacy and potential to induce negative side effects in tobacco-and non-tobacco users as well as degree of satisfaction with product handling. The HP concentrations were near the regulation limit for bleaching products of 6% set by the European Union in 2011. Materials and Methods: The clinical trial was randomized, single-blind and included 41 patients (93% completed) who were allocated into three bleaching groups: non-tobacco users treated with either 16% (corresponding to 5.8% HP) or 22% (corresponding to 7.9% HP) carbamide peroxide (CP) and tobacco users treated with 22% CP. Total bleaching time was 10.5 hours within 14 days. Tooth shade was visually assessed using a commercial shade guide. Side effects and satisfaction with the bleaching outcome and product handling were reported through a perception scale and a questionnaire. Results: Tooth lightening was similar (p>0.05) and significantly increased (p<0.05) for all groups. Patient age (> 31 years) was negatively correlated (p<0.05) and tobacco use was positively correlated (p<0.05) with bleaching efficacy. A percentage of 97% (n=38) of the patients experienced some form and degree of side effect, most frequently tooth hypersensitivity and gingival irritation. Patient satisfaction with the bleaching result was positively correlated with the user-friendliness of the product (p<0.05). Conclusion: A large number of side effects were reported after bleaching treatment with OTC products after a short treatment time. Prior to bleaching, patients should be informed of the major individual differences in both bleaching efficacy and degree and number of side effects.
The International journal of oral & maxillofacial implants
Porous titanium granules (PTG) may have potential as an osteoconductive bone graft substitute to ... more Porous titanium granules (PTG) may have potential as an osteoconductive bone graft substitute to treat peri-implant osseous defects. The aim of this study was to analyze clinical and radiographic outcomes of peri-implant osseous defects after treatment with PTG. This prospective, randomized, case-control, clinical 12-month study compared open-flap debridement and surface decontamination with titanium curettes and 24% ethylenediaminetetraacetic acid gel (n = 16) to the same protocol but with the addition of PTG (n = 16). One-, two-, and three-wall infrabony defects were included. Patients were given amoxicillin and metronidazole 3 days before surgery and for 7 days afterwards. Implants were submerged and allowed to heal for 6 months. Probing pocket depths, bleeding on probing, implant stability using resonance frequency analysis, and radiographic evaluation were performed at baseline and at 12 months. The threshold for significance was set at .05. Change in radiographic defect height...
The International journal of oral & maxillofacial implants
Porous titanium granules (PTG) may have potential as an osteoconductive bone graft substitute to ... more Porous titanium granules (PTG) may have potential as an osteoconductive bone graft substitute to treat peri-implant osseous defects. The aim of this study was to analyze clinical and radiographic outcomes of peri-implant osseous defects after treatment with PTG. This prospective, randomized, case-control, clinical 12-month study compared open-flap debridement and surface decontamination with titanium curettes and 24% ethylenediaminetetraacetic acid gel (n = 16) to the same protocol but with the addition of PTG (n = 16). One-, two-, and three-wall infrabony defects were included. Patients were given amoxicillin and metronidazole 3 days before surgery and for 7 days afterwards. Implants were submerged and allowed to heal for 6 months. Probing pocket depths, bleeding on probing, implant stability using resonance frequency analysis, and radiographic evaluation were performed at baseline and at 12 months. The threshold for significance was set at .05. Change in radiographic defect height...
In contrast to conventional casting methods for the production of a metallic crown the Procera pr... more In contrast to conventional casting methods for the production of a metallic crown the Procera process is based on precision machine duplication of models combined with spark erosion of the metal frame. Some of the steps in the manual handling procedure are thereby excluded. The present study evaluated, by means of a replica technique, the fit or adaptation of Procera titanium crowns to the stone die and in vivo to the tooth before cementation. For any combination, the marginal adaptation was superior to and significantly better than the occlusal areas and axial surfaces, respectively. In addition, the crowns had a significantly better fit to the stone die than to the tooth. The marginal discrepancy was approximately 60 microns in vitro and 70 microns in vivo, with a range of 3-205 microns.
The dental records of 638 patients treated with 788 posts and cores were studied to analyze failu... more The dental records of 638 patients treated with 788 posts and cores were studied to analyze failure rate and failure characteristics for two post designs. Frequency of the technical failures, loss of retention, root fracture, and post fracture were recorded 4 to 5 years after post cementation. There were two types of posts: custom-cast tapered posts and parallel-sided serrated posts. The cumulative failure rate was 15% for 456 tapered posts and 8% for 332 Para-Post posts. Loss of retention was the most frequent reason for failure for both types of posts, whereas root fractures had the most serious consequences, and all resulted in extraction. A significantly higher success rate was recorded for parallel-sided serrated posts, compared with custom-cast posts, regarding the total failure rate and the severity of the failure (p < 0.05).
Comparatively few studies are available reporting at least 5 years of follow-up data of implant-s... more Comparatively few studies are available reporting at least 5 years of follow-up data of implant-supported single-tooth replacements. To evaluate prospectively the 5-year outcome of implant-supported single-tooth prosthetic restorations. Forty subjects (mean age 41 years), 23 males and 17 females, who required single-tooth prosthetic replacement for a missing tooth were recruited. A total of 45 self-tapping implants (Astra Tech ST-implants)--40 in the maxilla and five in the mandible--were installed in a two-stage procedure. Abutment connection was performed 3-6 months after implant installation. Clinical and radiographic examinations were performed at the completion of the prosthetic treatment and once a year during a 5-year follow-up period. The analysis of peri-implant bone level alteration was performed on subject and implant levels and by the use of analysis of variance and binary logistic regression. Three patients were lost during the 5 years of follow-up. One implant was lost after 2.5 years in function and another four implants could not be accounted for at the 5-year follow-up examination. The overall failure rate at 5 years was 2.6% (subject level) and 2.3% (implant level). The mean loss of marginal bone at the implants during the first year in function was 0.06 mm (SD 0.67) on the subject level and 0.02 mm (0.65) on the implant level. During the subsequent 4 years the annual change in peri-implant bone level amounted to -0.02 mm (0.22) on both subject and implant levels. Thus, the mean total bone level change over the 5-year interval was -0.14 mm (1.04) on subject level and -0.11 mm (1.00) on the implant level of analysis (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;0.05). The frequency of implants with a 5-year bone loss of &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; or =1 mm was 13%. Approximately 50% of the implants demonstrated no bone loss. The present clinical trial on single-tooth replacements with the Astra Tech implant system demonstrated that the bone loss during the first year of function as well as annually thereafter was small.
Purpose: The aims of this study were to assess changes in the microhardness and surface roughness... more Purpose: The aims of this study were to assess changes in the microhardness and surface roughness of a dual-cured composite resin cement after water storage for different periods of time. Materials and methods: Sixty specimens were divided into four groups comprising high- and low-viscosity cement specimens stored either dry or in water for 1 to 60 days. Microhardness and surface roughness measurements were made after 1, 7, and 60 days of storage. Results: It was found that that although interactions complicated the interpretation of the results, the water-stored samples had a significantly lower microhardness compared to the dry-stored specimens for every time interval. In addition, the high-viscosity specimens had a significantly higher microhardness compared to the low-viscosity specimens. An increased microhardness was found for all groups, except for the low-viscosity, water-stored specimens after 60 days of water storage, which was attributed to an effect of the chemical postcuring process. Although difficult to evaluate from a clinical point of view, the laser profilometry analysis revealed that a significantly increased surface roughness was found after water storage and increased storage time that was possibly caused by a deterioration of the resin-matrix surface. Conclusion: For the permanency of the interfacial luting material, a high microhardness value seems to be important.
Due to their inertness and unsurpassed aesthetic properties, ceramic materials are increasingly u... more Due to their inertness and unsurpassed aesthetic properties, ceramic materials are increasingly used as inlay materials. Based on a questionnaire, the frequency and character of complications related to ceramic inlay therapy were assessed and some important pitfalls and clinical relevant factors discussed. A majority of the dentists performed between 1 and 10 ceramic inlays per month using several different ceramic materials. As many as 85% of the dentists had observed complications in connection w^ith ceramic inlays. Most frequency reported was hypersensitivity of a transient nature (15%). The material revealed an overall inlay fracture frequency of 5%, but the individual variations were high. Tooth fracture, loss of retention and other complications such as secondary caries, endodontic envolvement, colour mismatch and a surface and edge deterioration occurred w^ith a varying but low^er frequency. Failure analysis revealed a large number of causative factors among w^hich cavity and inlay design, bonding procedures, selection of luting material and proper case selection were regarded as the most important. Due consideration to the strength of remaining tooth substance w^as found to be important in reducing the problem of hypersensitivity and the risk of tooth and inlay fracture.
In the present study we investigated the prevalence of self-reported hand eczema as well as subje... more In the present study we investigated the prevalence of self-reported hand eczema as well as subjective associations between skin symptoms and composite/bonding or other dental materials among Swedish dentists. A questionnaire on skin symptoms, atopy, occupational experience, and other background factors was sent to a random sample (n~3,500) of all dentists licenced since 1965. This group corresponds to about half of the country's occupationally active dentists. The response rate was 88%. The questionnaire had previously been validated against clinical dermatological examination of subjects reporting hand eczema. The prevalence of dry and rough skin on the hands was high (45%). Hand eczema during the previous 12 months was reported by 13.5%. Dry skin and hand eczema were more common among dentists than in two age-matched general population samples investigated using identical questions. The difference versus the general population was most pronounced (about twofold) among male dentists. A history of childhood eczema was the most important predictor for adult hand eczema, with a prevalence ratio of 2.4 compared to dentists without childhood eczema. Seven % reported skin symptoms when working with acrylic resins, and 15% had experienced rapid itching related to protective gloves.
By means of a questionnaire, clinical examination and force recordings, the relationships between... more By means of a questionnaire, clinical examination and force recordings, the relationships between self‐assessed masticatory ability, dental state and bite force were studied in 160 80‐year‐old persons, 74 men and 86 women. The subjects were in general satisfied with their masticatory ability and 70% had no problems, while 6% reported three or more problems with mastication. Half of the subjects were dentate without removable prostheses and almost one‐third had 20 or more natural teeth. The edentulous persons (about one‐fifth of all) reported more problems related to mastication than the other dentition groups. The maximal bite force varied much and exhibited a significant correlation to the number of remaining teeth and dental state. The self‐assessed masticatory ability was only weakly correlated with dental state and bite force. It was concluded that many subjects with few or no remaining teeth and/or removable dentures had only few complaints of impaired masticatory function and showed a good adaptation to an impaired dental status and small maximal bite force.
Objective: The aim of this study was to retrospectively analyze whether the inclusion of cantilev... more Objective: The aim of this study was to retrospectively analyze whether the inclusion of cantilever extensions increased the amount of marginal bone loss at free‐standing, implant‐supported, fixed partial dentures (FPDs) over a 5‐year period of functional loading.Material and Methods: The patient material comprised 45 periodontally treated, partially dentate patients with a total of 50 free‐standing FPDs supported by implants of the Astra Tech® System. Following FPD placement (baseline) the patients were enrolled in an individually designed supportive care program. A set of criteria was collected at baseline to characterize the FPDs. The primary outcome variable was change in peri‐implant bone level from the time of FPD placement to the 5‐year follow‐up examination. The comparison between FPDs with and without cantilevers was performed at three levels: FPD level, implant level, and surface level. Bivariate analysis was performed by the use of the Mann–Whitney U‐test and stepwise regression analysis was utilized to evaluate the potential influence of confounding factors on the change in peri‐implant bone level.Results: The overall mean marginal bone loss for the implant‐supported FPDs after 5 years in function was 0.4 mm (SD, 0.76). The bone level change at FPDs placed in the maxilla was significantly greater than that for FPDs in the mandible (0.6 versus 0.2 mm; p&lt;0.05). No statistically significant differences were found with regard to peri‐implant bone level change over the 5 years between FPDs with and without cantilevers at any of the levels of comparisons. The multivariate analysis revealed that the variables jaw of treatment and smoking had a significant influence on peri‐implant bone level change on the FPD level, but not on the implant or surface levels. The model explained only 10% of the observed variance in the bone level change.Conclusion: The study failed to demonstrate that the presence of cantilever extensions in an FPD had an effect on peri‐implant bone loss.
Cytotoxic methacrylate monomers have been identified in aqueous extracts of freshly cured compome... more Cytotoxic methacrylate monomers have been identified in aqueous extracts of freshly cured compomers. Some of these compounds, including HEMA and TEGDMA, induce apoptosis and necrosis in vitro. The aim of the present study was to elucidate possible signaling pathways involved in apoptosis following exposure to HEMA or TEGDMA in a salivary gland cell line. The cells were exposed to various concentrations of HEMA or TEGDMA. ROS formation was determined by dichlorofluorescein assay. Phosphorylated MAP-kinases ERK1/2, p38 and JNK, as well as specific caspases were identified by Western blotting. Apoptosis was assayed by fluorescence microscopy. HEMA or TEGDMA exposure resulted in ROS formation and concentration-dependent apoptosis as well as phosphorylation of ERK. Phosphorylation of JNK and p38 was induced by HEMA. Selective inhibitors of ERK and JNK modified the apoptotic response after HEMA and TEGDMA exposure, whereas p38 inhibition modified the apoptotic response only after HEMA exposure. Vitamin C reduced HEMA-induced apoptosis. ROS formation and differential MAP kinase activation appear to be involved in the apoptotic response following exposure to HEMA and TEGDMA.
Objectives. Digital impressions are increasingly used and have the potential to avoid the problem... more Objectives. Digital impressions are increasingly used and have the potential to avoid the problem of inaccurate impressions. Only a few studies to verify the accuracy of digital impressions have been performed. The purpose of this study was to compare the marginal and internal fit of 3-unit tooth supported fixed dental prostheses (FDPs) fabricated from digital and conventional impressions. Methods. Ten FDPs were produced from digital impressions using the iTero system and 10 FDPs were produced using vinyl polysiloxane (VPS) impression material. A triple-scan protocol and CAD software were used for measuring and calculating discrepancies of the FDPs at 3 standard areas: mean internal discrepancy, absolute marginal gap, and cervical area discrepancy. The Mann-Whitney U test was used for analyzing the results. Results. For conventional and digital impressions, respectively, FDPs had an absolute marginal gap of 147 m and 142 m, cervical area discrepancy of 69 m and 44 m, and mean internal discrepancy of 117 m and 93 m. The differences were statistically significant in the cervical and internal areas (< 0.001). Significance. The results indicated that the digital impression technique is more exact and can generate 3-unit FDPs with a significantly closer fit compared to the VPS technique.
Dentistry usually is &amp;amp;#39;wet work&amp;amp;#39; with risk of damage to the skin b... more Dentistry usually is &amp;amp;#39;wet work&amp;amp;#39; with risk of damage to the skin barrier, and the hands may be exposed to skin irritants and contact-sensitizing substances used in dental materials or gloves. Airway irritants may also be present. This study assessed the consequences of work-related skin and airway symptoms among dentists in terms of contact with health authorities, sick leave, or changes in the professional career. A questionnaire on these factors was answered by more than 3000 Swedish dentists. Only 6% of the respondents had consulted a physician, although 22% had noted work-related skin symptoms. In 2% the skin symptoms had caused sick leave, and about 2% had reported their skin symptoms as an occupational disease. Two per cent had consulted a physician owing to work-related airway symptoms, which is a minor part of the 13% who had experienced such symptoms when in contact with dental materials. Twenty-five dentists (&amp;amp;lt;1%) had been on sick leave because of work-related airway symptoms. Only 1 dentists reported change of activities or occupation owing to work-related skin or airway symptoms, and in most cases these symptoms only contributed to their decision. In summary, whereas sick leave in dentists because of musculoskeletal problems may be common, the present study shows that this is not the case for work-related skin or airway symptoms, and such symptoms seldom affect the dentists&amp;amp;#39; professional career.
NIOM i endring NIOM har fått ny logo og har endret navn fra Nordisk institutt for odontologisk ma... more NIOM i endring NIOM har fått ny logo og har endret navn fra Nordisk institutt for odontologisk materialprøvning til Nordisk Institutt for Odontologiske Materialer. Artikkelen beskriver den modernisering som instituttet har gjennomgått.
Water sorption and solubility of six proprietary composite resin materials were assessed, and mon... more Water sorption and solubility of six proprietary composite resin materials were assessed, and monomers eluted from the organic matrix during water storage identi®ed. Water sorption and solubility tests were carried out with the following storage times: 4 h, 24 h and 7, 60 and 180 days. After storage, water sorption and solubility were determined. Eluted monomers were analysed by high performance liquid chromatography (HPLC). Correlation between the retention time of the registered peak and the reference peak was observed, and UV-spectra con®rmed the identity. The results showed an increase in water sorption until equilibrium for all materials with one exception. The solubility behaviour of the composite resin materials tested revealed variations, with both mass decrease and increase. The resin composition in¯uences the water sorption and solubility behaviour of composite resin materials. The HPLC analysis of eluted components revealed that triethyleneglycol dimethacrylate (TEGDMA) was the main monomer released. Maximal monomer concentration in the eluate was observed after 7 days. During the test period, quanti®able quantities of urethanedimethacrylate (UEDMA) monomer were observed, whereas 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)-phenyl]propane (Bis-GMA) was only found in detectable quantities. No detectable quantities of bisphenol-A were observed during the test period.
Purpose: The aim of this in vitro study was to evaluate the load resistance in a conical implant ... more Purpose: The aim of this in vitro study was to evaluate the load resistance in a conical implant system by comparing combinations of 2 different abutment head angles and 3 different retaining screw materials. Materials and methods: The retaining screw materials (titanium alloy, gold alloy, and commercially pure titanium) were tested with abutment-head angles of 20 degrees and 45 degrees. Six groups of 10 specimens each were prepared. An oblique (30-degree) compression test was performed in a Lloyd LRX universal testing machine with the abutment attached to a superstructure with a retaining screw. All specimens were loaded until fracture or permanent deformation occurred. The results were evaluated statistically with Wilcoxon signed rank test for variance distribution (P < .05 considered significant). Results: There were statistically significant differences in load resistance between 20-degree and 45-degree abutments. The titanium screws (titanium alloy and commercially pure) in the 45-degree abutment group had almost equal mean values, while the gold alloy had a significantly lower value. In the 20-degree abutment group, significantly higher values were found with commercially pure titanium compared to titanium alloy and gold alloy, but the difference between the values for the gold and titanium alloys was not significant. Discussion: The angulation of the abutment head played the most significant role in determining the amount of load withstood, but the material used for the screw was also relevant. Conclusion: A 45-degree abutment can be combined with a retaining screw of any of these materials to create a functional implant system. The test also substantiated that, irrespective of the retaining-screw material, a 20-degree abutment could resist loading forces of at least 900 N.
Objective: To compare two home-based over-the-counter (OTC) bleaching tray products with similar ... more Objective: To compare two home-based over-the-counter (OTC) bleaching tray products with similar hydrogen peroxide (HP) concentrations with respect to tooth lightening efficacy and potential to induce negative side effects in tobacco-and non-tobacco users as well as degree of satisfaction with product handling. The HP concentrations were near the regulation limit for bleaching products of 6% set by the European Union in 2011. Materials and Methods: The clinical trial was randomized, single-blind and included 41 patients (93% completed) who were allocated into three bleaching groups: non-tobacco users treated with either 16% (corresponding to 5.8% HP) or 22% (corresponding to 7.9% HP) carbamide peroxide (CP) and tobacco users treated with 22% CP. Total bleaching time was 10.5 hours within 14 days. Tooth shade was visually assessed using a commercial shade guide. Side effects and satisfaction with the bleaching outcome and product handling were reported through a perception scale and a questionnaire. Results: Tooth lightening was similar (p>0.05) and significantly increased (p<0.05) for all groups. Patient age (> 31 years) was negatively correlated (p<0.05) and tobacco use was positively correlated (p<0.05) with bleaching efficacy. A percentage of 97% (n=38) of the patients experienced some form and degree of side effect, most frequently tooth hypersensitivity and gingival irritation. Patient satisfaction with the bleaching result was positively correlated with the user-friendliness of the product (p<0.05). Conclusion: A large number of side effects were reported after bleaching treatment with OTC products after a short treatment time. Prior to bleaching, patients should be informed of the major individual differences in both bleaching efficacy and degree and number of side effects.
The International journal of oral & maxillofacial implants
Porous titanium granules (PTG) may have potential as an osteoconductive bone graft substitute to ... more Porous titanium granules (PTG) may have potential as an osteoconductive bone graft substitute to treat peri-implant osseous defects. The aim of this study was to analyze clinical and radiographic outcomes of peri-implant osseous defects after treatment with PTG. This prospective, randomized, case-control, clinical 12-month study compared open-flap debridement and surface decontamination with titanium curettes and 24% ethylenediaminetetraacetic acid gel (n = 16) to the same protocol but with the addition of PTG (n = 16). One-, two-, and three-wall infrabony defects were included. Patients were given amoxicillin and metronidazole 3 days before surgery and for 7 days afterwards. Implants were submerged and allowed to heal for 6 months. Probing pocket depths, bleeding on probing, implant stability using resonance frequency analysis, and radiographic evaluation were performed at baseline and at 12 months. The threshold for significance was set at .05. Change in radiographic defect height...
The International journal of oral & maxillofacial implants
Porous titanium granules (PTG) may have potential as an osteoconductive bone graft substitute to ... more Porous titanium granules (PTG) may have potential as an osteoconductive bone graft substitute to treat peri-implant osseous defects. The aim of this study was to analyze clinical and radiographic outcomes of peri-implant osseous defects after treatment with PTG. This prospective, randomized, case-control, clinical 12-month study compared open-flap debridement and surface decontamination with titanium curettes and 24% ethylenediaminetetraacetic acid gel (n = 16) to the same protocol but with the addition of PTG (n = 16). One-, two-, and three-wall infrabony defects were included. Patients were given amoxicillin and metronidazole 3 days before surgery and for 7 days afterwards. Implants were submerged and allowed to heal for 6 months. Probing pocket depths, bleeding on probing, implant stability using resonance frequency analysis, and radiographic evaluation were performed at baseline and at 12 months. The threshold for significance was set at .05. Change in radiographic defect height...
In contrast to conventional casting methods for the production of a metallic crown the Procera pr... more In contrast to conventional casting methods for the production of a metallic crown the Procera process is based on precision machine duplication of models combined with spark erosion of the metal frame. Some of the steps in the manual handling procedure are thereby excluded. The present study evaluated, by means of a replica technique, the fit or adaptation of Procera titanium crowns to the stone die and in vivo to the tooth before cementation. For any combination, the marginal adaptation was superior to and significantly better than the occlusal areas and axial surfaces, respectively. In addition, the crowns had a significantly better fit to the stone die than to the tooth. The marginal discrepancy was approximately 60 microns in vitro and 70 microns in vivo, with a range of 3-205 microns.
The dental records of 638 patients treated with 788 posts and cores were studied to analyze failu... more The dental records of 638 patients treated with 788 posts and cores were studied to analyze failure rate and failure characteristics for two post designs. Frequency of the technical failures, loss of retention, root fracture, and post fracture were recorded 4 to 5 years after post cementation. There were two types of posts: custom-cast tapered posts and parallel-sided serrated posts. The cumulative failure rate was 15% for 456 tapered posts and 8% for 332 Para-Post posts. Loss of retention was the most frequent reason for failure for both types of posts, whereas root fractures had the most serious consequences, and all resulted in extraction. A significantly higher success rate was recorded for parallel-sided serrated posts, compared with custom-cast posts, regarding the total failure rate and the severity of the failure (p < 0.05).
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Papers by Stig Karlsson