Comparison of intraoral biofilm reduction on silver-coated and silver ion-implanted stainless steel bracket material : Biofilm reduction on silver ion-implanted bracket material.

PURPOSE: The objective of this in situ study was to quantify the intraoral biofilm reduction on bracket material as a result of different surface modifications using silver ions. In addition to galvanic silver coating and physical vapor deposition (PVD), the plasma immersion ion implantation and deposition (PIIID) procedure was investigated for the first time within an orthodontic application. MATERIALS AND METHODS: An occlusal splint equipped with differently silver-modified test specimens based on stainless steel bracket material was prepared for a total of 12 periodontally healthy patients and was worn in the mouth for 48 h. The initially formed biofilm was fluorescently stained and a quantitative comparative analysis of biofilm volume, biofilm surface coverage and live/dead distribution of bacteria was performed by confocal laser scanning microscopy (CLSM). RESULTS: Compared to untreated stainless steel bracket material, the antibacterial effect of the PIIID silver-modified surface was just as significant with regard to reducing the biofilm volume and the surface coverage as the galvanically applied silver layer and the PVD silver coating. Regarding the live/dead distribution, however, the PIIID modification was the only surface that showed a significant increase in the proportion of dead cells compared to untreated bracket material and the galvanic coating. CONCLUSIONS: Orthodontic stainless steel with a silver-modified surface by PIIID procedure showed an effective reduction in the intraoral biofilm formation compared to untreated bracket material, in a similar manner to PVD and galvanic silver coatings applied to the surface. Additionally, the PIIID silver-modified surface has an increased bactericidal effect.

Comparative three-dimensional analysis of initial biofilm formation on three orthodontic bracket materials.

INTRODUCTION: The purpose of the present study was to investigate and compare early biofilm formation on biomaterials, which are being used in contemporary fixed orthodontic treatment. METHODS: This study comprised 10 healthy volunteers (5 females and 5 males) with a mean age of 27.3 +-3.7 years. Three slabs of different orthodontic materials (stainless steel, gold and ceramic) were placed in randomized order on a splint in the mandibular molar region. Splints were inserted intraorally for 48 h. Then the slabs were removed from the splints and the biofilms were stained with a two color fluorescence assay for bacterial viability (LIVE/DEAD BacLight-Bacterial Viability Kit 7012, Invitrogen, Mount Waverley, Australia). The quantitative biofilm formation was analyzed by using confocal laser scanning microscopy (CLSM). RESULTS: The biofilm coverage was 32.7 ± 37.7% on stainless steel surfaces, 59.5 ± 40.0% on gold surfaces and 56.8 ± 43.6% on ceramic surfaces. Statistical analysis showed significant differences in biofilm coverage between the tested materials (p=0.033). The Wilcoxon test demonstrated significantly lower biofilm coverage on steel compared to gold (p=0.011). Biofilm height on stainless steel surfaces was 4.0 ± 7.3 µm, on gold surfaces 6.0 ± 6.6 µm and on ceramic 6.5 ± 6.0 µm. The Friedman test revealed no significant differences between the tested materials (p=0.150). Pairwise comparison demonstrated significant differences between stainless steel and gold (p=0.047). CONCLUSION: Our results indicate that initial biofilm formation seemed to be less on stainless steel surfaces compared with other traditional materials in a short-term observation. Future studies should examine whether there is a difference in long-term biofilm accumulation between stainless steel, gold and ceramic brackets.

Microbial diversity of peri-implant biofilms on implant fixed bar and telescopic double crown attachments.

One of the principal problems in oral implantation is inflammation of peri-implant hard and soft tissues caused by bacterial biofilms. The purpose of the present study was to evaluate the microbial diversity of peri-implant biofilms on 2 different implant-anchored attachment types in vivo. Samples of peri-implant sulcus fluid were collected from 8 patients with implant-supported bar attachments and 8 patients with implant-anchored telescopic double crown attachments. Samples of sulcus fluid of the adjacent teeth were also collected from the partially edentulous patients with implant fixed telescopic double crowns. The mixed amplicons of 16S rRNA fragments of different bacterial origins were separated by use of single-strand conformation polymorphism analysis to identify the predominant bacterial genera. With 3.5 ± 2.1 different predominant bacterial genera in the sulcus fluid surrounding implant-supported bar attachments and 6.3 ± 3.1 different predominant genera in the sulcular fluid of implant-anchored double crown attachments, the differences were not statistically significant (P = .11). The microbial diversity in the sulcus fluid surrounding the remaining dentition was similar to that of the implant fixed telescopic attachments (6.3 ± 2.1). Aside from host response and other individual factors, the microbial diversity of peri-implant biofilms seems to be impaired by cofactors such as the possibility of cleaning the implant-supported supraconstructions and the different plaque-retaining sites. Nevertheless, these differences do not lead to statistically significant differences in the microbial diversity of peri-implant plaques.

The influence of simulated aging on the mechanical properties of orthodontic elastomeric chains without an intermodular link.

OBJECTIVE: Orthodontic elastomeric chains are a main component in orthodontic therapy with fixed vestibular or lingual appliances. The objective of this study was to investigate the influence of artificial aging on the mechanical properties of orthodontic elastomeric chains (power chains, PCs) without an intermodular link using a test setup according to DIN EN ISO 21606:2007. MATERIAL AND METHODS: In this study, 11 types of PCs supplied by seven manufacturers were investigated. Four groups with 10 specimens each were randomly generated for each type. Samples were separately mounted in a universal testing machine and extended by 300% (four times their initial length) at a crosshead rate of 100 mm/min and were held at this position for five seconds. The chain length was then reduced to three times the initial length (extension by 200%) and kept for 30 s. Then, within the control group (t = 0) and the force Fmin was recorded before extension until failure was performed and force (Fmax) and length (Lmax) at failure were determined. After prestretching, specimens of the three other groups were stored in water at 37°C with its three times initial length for one day (t = 1), 14 days (t = 2), and 28 days (t = 3), respectively. The specimens were then placed in the universal testing machine and the residual force (Fmin) measured, so as to subsequently extend them until failure at Fmax and Lmax. Data were statistically analyzed by one-way analysis of variance; the level of significance was set at p = 0.05. RESULTS: Statistical analysis revealed significant differences in Fmax, Fmin, and Lmax in each group (t = 0 to t = 3) between the various manufacturers (p < 0.001). Moreover, artificial aging significantly influenced Fmax, Fmin, and Lmax (p < 0.001). CONCLUSION: The orthodontist should consider both the mechanical properties of PCs and the duration of these appliances' application when treating patients. Artificial aging had a significant influence on the parameters we determined (p <0.001).

Short-term periodontal and microbiological changes following orthognathic surgery.

OBJECTIVE: Aim of the present study was to evaluate the influence of orthognathic surgery on the development of periodontal and microbiological changes. MATERIALS AND METHODS: Fifteen consecutively treated patients with a mean age of 24.9±7.7 years receiving orthognathic surgery were included in the present study. Plaque index (PI) and concentrations of 11 periodonto-pathogenic bacteria were recorded one day prior to surgery (t(0)) and one week (t(1)) and six weeks (t(2)) post-surgery. In addition, a complete periodontal examination including pocket probing depth (PPD), gingival recession (GR), clinical attachment level (CAL), bleeding on probing (BOP) and width of keratinized gingiva (WKG) was conducted at t(0) and t(2). For statistical analysis, general linear model and paired t-test were applied. RESULTS: A significant increase of PI (t(0)-t(1), p=0.037) was followed by a significant decrease (t(1)-t(2), p=0.017). Apart from Eikenella corrodens (p=0.036), no significant microbiological changes were recorded. PPD significantly increased on oral sites (p=0.045) and GR especially on buccal sites (p=0.001). In the incision area the development of GR was significantly higher on the test (buccal) than on the control sites (oral). Both gingival biotypes were affected by GR. CONCLUSIONS: Orthognathic surgery causes statistically significant changes of periodontal parameters, but these changes do not necessarily impair the aesthetic appearance of the gingival margin.

Influence of orthognathic surgery on periodontal tissues: short-term results.

OBJECTIVE: The present prospective study aimed at evaluating the influence of orthognathic surgery on mucogingival tissues and the subgingival microflora. PATIENTS AND METHODS: Fifteen consecutively-treated patients with a mean age of 24.9±7.7 years were included in this study. The surgical interventions comprised the Le Fort I osteotomy of the maxilla and/or sagittal split osteotomy of the mandible. The following periodontal and microbial parameters were measured preoperatively (T(0)) as well as 1 week (T(1)) and 6 weeks (T(2)) postoperatively: pocket probing depth (PPD), gingival recession (GR), clinical attachment level (CAL), bleeding on probing (BOP), plaque index (PI), and changes in the subgingival microflora. Periodontal parameters were calculated for all sites as well as for buccal and oral sites separately. For statistical analysis, the general linear model and paired t test were applied (level of significance: p<0.05). RESULTS: PPD readings increased significantly on oral tooth sites when T(0) values were compared to T(1) (p=0.009) and T(2 )values (p=0.042). GR increased significantly on buccal sites from 0.10±0.16 mm at baseline to 0.21±0.23 mm at T(1) (p=0.013) and 0.31±0.31 mm at T(2) (p=0.001). Furthermore, we noted significant changes in the CAL (oral sites) and PI (buccal and oral sites). We observed no significant differences in BOP and periodontopathogenetic bacteria. CONCLUSION: Orthognathic surgery has a statistically significant effect on the development of gingival recessions. However, this effect may not necessarily clinically impair the esthetic appearance.

Comparative analysis of biofilm formation on dental implant abutments with respect to supra- and subgingival areas: polytetrafluoroethylene versus titanium.

The aim of the present in vivo study was to examine the effect of polytetrafluoroethylene (PTFE) surfaces on biofilm formation on dental implant abutments in comparison to titanium surfaces. Fifteen modified abutments with incorporated PTFE plates were inserted in 10 patients for 14 days. Scanning electron microscopy techniques were used to examine biofilm formation on different surfaces and to determine the percentage of surface coverage. Significantly less biofilm was detected on PTFE surfaces than on titanium surfaces. The results of this study reveal that PTFE surfaces reduce biofilm formation to a minimum on dental implant abutments. Int J Prosthodont 2011;24:373-375.

Comparative analysis of long-term biofilm formation on metal and ceramic brackets.

OBJECTIVE: To test the null hypothesis that stainless steel and ceramic brackets show no differences in biofilm adhesion. MATERIALS AND METHODS: Twenty adolescents (6 boys, 14 girls) who had received fixed orthodontic therapy for 18.9 ± 3.2 months were divided into a metal and a ceramic bracket group. Thirty brackets per group were taken from central incisors, canines, and second premolars and quantitatively analyzed for biofilm coverage with the Rutherford backscattering detection method. Five micrographs were obtained per bracket with views from the buccal, mesial, distal, gingival, and occlusal aspects, resulting in a total of 300 images. Biofilm formation between groups was compared using the Mann-Whitney U-test (α = .05). RESULTS: Total biofilm formation was 12.5% ± 5.7% (3.3 ± 1.6 mm(2)) of the surface on metal and 5.6% ± 2.4% (1.5 ± 0.6 mm(2)) on ceramic brackets. Differences between groups were statistically significant (P < .05). A pairwise comparison of biofilm formation revealed significantly lower biofilm formation on ceramic brackets with respect to intraoral location (central incisor, canine, second premolar) and bracket surface (buccal, mesial, distal). CONCLUSIONS: The hypothesis was rejected. The results indicate that ceramic brackets exhibit less long-term biofilm accumulation than metal brackets.

Tensile properties of orthodontic elastomeric chains.

AIM: Orthodontic elastomeric chains are a main component in orthodontic therapy employing labial or lingual appliances. The aim of this study was to investigate the tensile properties of orthodontic elastomeric chains with a test setup according to ISO 21606:2007. MATERIAL AND METHODS: Orthodontic elastomeric chains of eight manufacturers with and without an intermodular link were obtained from commercially-available stock, yielding 23 groups with ten specimens each. Samples were mounted in a universal testing machine and extended at a rate of 100 mm/min to four times the initial length and held for 5 seconds. After 5 seconds, the chain lengths were reduced to an extension of three times the initial length and held for 30 seconds before extension until failure. Forces at four times the test length (Fmax1), three times the initial length (Fmin) as well as force (Fmax2) and length (Lmax) at failure were recorded. Data were statistically analyzed by one-way analysis of variance using SPSS® 17. The level of significance was set at p = 0.05. RESULTS: Statistical analysis revealed significant differences in Fmax1, Fmin, Fmax2 and Lmax among the various manufacturers. Fmax1 ranged between 9.1 N and 23.2 N, Fmin ranged between 1.5 N and 3.0 N, Fmax2 ranged between 15.7 N and 34.0 N, and Lmax ranged between 425% and 629% of the initial length. CONCLUSIONS: The tensile properties of different manufacturers of elastomeric orthodontic chains differ statistically significantly. Hence the amount of orthodontic force that is applied depends significantly on the type of elastomeric chains used in combination with labial or lingual appliances.

Comparative analysis of slot dimension in lingual bracket systems.

BACKGROUND: Orthodontic treatment with fixed appliances requires - among others - the correct clinical expression of torque, which depends on the precise fitting of archwire and slot. Especially in the lingual technique torque problems become clinically more evident than in labial appliances also with respect to the vertical alignment of teeth due to different distances from the center of resistance. The purpose of the present study was to compare the preciseness of slot dimensions of different lingual bracket systems. METHODS: Three lingual bracket systems were included in the study (7th Generation and STb, Ormco, Glendora, CA, USA; Incognito, TOP-Service/3 M Unitek, Monrovia, CA, USA). Non destructive analysis of vertical slot dimensions was performed using precision pin gauges (Azurea, Belprahon, Switzerland) that were tapered in increments of 0.002 mm (0.00008 inch). The sizes of 240 incisor and canine brackets were measured per system (total: 720). Data were compared using one-way ANOVA. A p-value < 0.05 was considered statistically significant. RESULTS: Average slot dimensions were 0.467 mm +/- 0.007 mm (0.0184 inch +/- 0.0003 inch) for the 7th Generation bracket system, 0.466 mm +/- 0.004 mm (0.0183 inch +/- 0.0001) inch for the STb bracket system and 0.459 mm +/- 0.004 mm (0.0181 inch +/- 0.0001) inch for the Incognito bracket system. Differences between systems were statistically significant (p < 0.05). CONCLUSIONS: The analyzed bracket systems for lingual treatment exhibited significant differences in slot dimension that will clinically result in torque play. These aspects must be considered in lingual orthodontic treatment.

A comparison of change in condylar position in asymptomatic volunteers utilizing a stabilization and a pivot appliance.

Although different occlusal appliances with various designs have been described in the literature, little is known about their influence on condylar position. The purpose of the present study was to compare the effect of two occlusal appliances (pivot appliance, stabilization appliance) on condylar position with respect to normal and maximum clenching force. Electronic-positioning-analysis was performed in 22 healthy volunteers with an ultrasound-based registration system. After randomized insertion of the appliances, the volunteers were asked to clench five times using normal and then maximum force. Data was compared using ANOVA for repeated measurements, with occlusal design and clenching force as covariables (alpha = 0.05). Insertion of appliances caused an anterior-downward movement of the condylar reference point (pivot appliance: 0.3 mm +/- 0.5 mm sagittally, 0.8 mm +/- 0.5 mm vertically; stabilization appliance: 0.2 mm +/- 0.5 mm sagittally, 0.8 mm +/- 0.5 mm vertically). In both appliances, maximum clenching force enhanced the anterior and reduced the downward position (pivot appliance: 0.4 mm +/- 0.5 mm sagittally, 0.6 mm +/- 0.5 mm vertically; stabilization appliance: 0.4 mm +/- 0.5 mm sagittally, 0.4 mm +/- 0.6 mm vertically). Within groups, the positions for normal and maximum clenching force were significantly different (p<0.001 in the sagittal and vertical dimension for both appliances). Comparison of occlusal design with respect to clenching force revealed no significant differences between both appliances. Insertion of both appliances induced an anterior-downward movement of the condylar reference point, whereas the two different occlusal designs had no influence on condylar position.

Supra- and subgingival biofilm formation on implant abutments with different surface characteristics.

PURPOSE: The aim of the present study was to establish a noninvasive method for quantitative analysis of supra- and subgingival biofilm formation on dental implants considering different surface modifications. MATERIALS AND METHODS: Patients of both sexes were included. They had to be in generally good health, partially edentulous, and the recipient of at least 1 screw-type implant with an abutment possessing supra- and subgingival areas. Healing abutments were inserted for 14 days. The abutment surfaces were divided into quadrants that were sandblasted, ground, acid-etched, and untreated (with the latter surface as a control). Biofilm formation on the healing abutments was analyzed using scanning electron microscopy, including secondary-electron and Rutherford backscattering-detection methods. Calculation of biofilm-covered surfaces was performed depending on grey-values, considering supra- and subgingival areas. After calculating absolute and relative biofilm-covered surfaces depending on localization, the influence of surface modification on biofilm formation was analyzed. RESULTS: Fifteen healing abutments were inserted in 11 patients. In all surface properties plaque adhesion in supragingival areas was significantly higher (17.3% +/- 23.1%) than in subgingival areas (0.8% +/- 1.0%). Biofilm accumulation in supragingival areas was significantly increasing by higher surface roughness, whereas this influence was not detected in subgingival areas. CONCLUSION: The described method is valuable for investigation of supra- and subgingival biofilm adhesion on surface-modified implant abutments. There was a significant influence of surface localization (supra- and subgingival) as well as surface modification on biofilm formation.