Influence of platform switching on bone-level alterations: a three-year randomized clinical trial

The concept of platform switching has been introduced to implant dentistry based on clinical observations of reduced peri-implant crestal bone loss. However, published data are controversial, and most studies are limited to 12 months. The aim of the present randomized clinical trial was to test the hypothesis that platform switching has a positive impact on crestal bone-level changes after 3 years. Two implants with a diameter of 4 mm were inserted crestally in the posterior mandible of 25 patients. The intraindividual allocation of platform switching (3.3-mm platform) and the standard implant (4-mm platform) was randomized. After 3 months of submerged healing, single-tooth crowns were cemented. Patients were followed up at short intervals for monitoring of healing and oral hygiene. Statistical analysis for the influence of time and platform type on bone levels employed the Brunner-Langer model. At 3 years, the mean radiographic peri-implant bone loss was 0.69 ± 0.43 mm (platform switching) and 0.74 ± 0.57 mm (standard platform). The mean intraindividual difference was 0.05 ± 0.58 mm (95% confidence interval: -0.19, 0.29). Crestal bone-level alteration depended on time (p < .001) but not on platform type (p = .363). The present randomized clinical trial could not confirm the hypothesis of a reduced peri-implant crestal bone loss, when implants had been restored according to the concept of platform switching.

Diagnostic accuracy of CBCT for periodontal lesions

OBJECTIVES

The present study compares the diagnostic value of periodontal bone defect images using conventional two-dimensional single-tooth radiographs and three-dimensional cone beam computed tomography (CBCT) images.

MATERIALS AND METHODS

Classified periodontal bone defects were prepared on pig mandibles and presented radiographically. Fifteen dentists were instructed to make a diagnosis based on these x-rays, regarding the type and the extent of the bone defects. Subsequently, the results were evaluated and compared to the morphology of the surgically prepared defects as the gold standard.

RESULTS

On average, the diagnosis of infrabony defects were 21 %, dehiscence 25 %, and fenestration 33 % more accurate using the three-dimensional projection than with the single-tooth radiograph. Furthermore, the CBCT allows grade II furcation to be captured more accurately.

CONCLUSIONS

The results of this study indicate that a considerably more precise analysis of periodontal defects is possible due to the third dimension. Particularly, in the oro-vestibular orientation, defects could be detected significantly more accurate.

CLINICAL RELEVANCE

CBCT images offer an advantageous alternative to the conventional single-tooth radiograph while taking the higher exposure of radiation into account.

NOD1 gene polymorphisms in relation to aggressive periodontitis

BACKGROUND

NOD proteins are part of innate immunity mechanisms. They play a role in epithelial barrier functions and inflammatory responses to bacteria. Single nucleotide polymorphisms (SNPs) in the NOD1 gene have proven to be associated with inflammatory bowel disease (IBD) and asthma.

OBJECTIVE

To investigate SNPs in the NOD1 gene in relation to aggressive periodontitis (AgP), a multifactorial, inflammatory disease of the supporting tissues of the teeth.

MATERIALS AND METHODS

Five SNPs in the NOD1 gene (4 intronic and 1 exonic) were tested for association in a total of 415 AgP patients and 874 controls both of Northern European ancestry.

RESULTS

The frequencies of the rare SNP alleles ranged between 21% and 26% among cases, and 20-27% among controls, and were not statistically different between cases and controls. Two SNPs were in strong linkage disequilibrium (r(2) = 0.97 in cases and 0.94 in controls). The overall haplotype distributions did not differ between cases and controls. We observed 8 haplotypes with a frequency of >or=1% among cases and/or controls, but none of these haplotype frequencies differed significantly among cases and controls. Logistic regression analyses with adjustment for gender and smoking status did not reveal significant associations with AgP for any of the 5 SNPs. This study had a power of >or=95% to detect associations with variants carrying relative risks of >or=1.5 for heterozygote carriers and >or=2.25 for homozygote carriers.

CONCLUSIONS

Although SNPs in the NOD1 gene have been strongly associated with cases of IBD, the current study failed to show an association of NOD1 SNPs with AgP.

Full-mouth disinfection for the treatment of adult chronic periodontitis

BACKGROUND

In an attempt to enhance treatment outcomes, alternative protocols for anti-infective periodontal therapy have been introduced.

OBJECTIVES

To evaluate the effectiveness of full-mouth disinfection or full-mouth scaling compared to conventional quadrant scaling for periodontitis.

SEARCH STRATEGY

Data sources included electronic databases, handsearched journals and contact with experts. The Cochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE were searched. Reference lists from relevant articles were scanned and the authors of eligible studies were contacted to identify trials and obtain additional information. Date of most recent searches: December 2006: (CENTRAL) (The Cochrane Library 2006, Issue 4).

SELECTION CRITERIA

Randomised controlled trials were selected with at least 3 months follow up comparing full-mouth scaling and root planing within 24 hours with (FMD) or without (FMS) the adjunctive use of an antiseptic (chlorhexidine) with conventional quadrant scaling and root planing (control). The methodological quality of the studies was assessed within the data extraction form, mainly focusing on: method of randomisation, allocation concealment, blindness of examiners and completeness of follow up.

DATA COLLECTION AND ANALYSIS

Data extraction and quality assessment were conducted independently by multiple review authors. The primary outcome measure was tooth loss, secondary outcomes were reduction of probing depth, bleeding on probing and gain in probing attachment. The Cochrane Collaboration statistical guidelines were followed.

MAIN RESULTS

The search identified 216 abstracts. Review of these abstracts resulted in 12 publications for detailed review. Finally, seven randomised controlled trials (RCTs) which met the criteria for eligibility were independently selected by two review authors. None of the studies included reported on tooth loss. All treatment modalities led to significant improvements in clinical parameters after a follow up of at least 3 months. For the secondary outcome, reduction in probing depth, the mean difference between FMD and control was 0.53 mm (95% confidence interval (CI) 0.28 to 0.77) in moderately deep pockets of single rooted teeth and for gain in probing attachment 0.33 mm (95% CI 0.04 to 0.62) in moderately deep single and multirooted teeth. Comparing FMD and FMS the mean difference in one study for gain in probing attachment amounted to 0.74 mm in favour of FMS (95% CI 0.17 to 1.31) for deep pockets in multirooted teeth, while another study reported a mean difference for reduction in bleeding on probing of 18% in favour of FMD (95% CI -33.74 to -2.26) for deep pockets of single rooted teeth. No significant differences were observed for any of the outcome measures, when comparing FMS and control.

AUTHORS' CONCLUSIONS

In patients with chronic periodontitis in moderately deep pockets slightly more favourable outcomes for pocket reduction and gain in probing attachment were found following FMD compared to control. However, these additional improvements were only modest and there was only a very limited number of studies available for comparison, thus limiting general conclusions about the clinical benefit of full-mouth disinfection.

Microbiological outcomes of quadrant versus full-mouth root planing as monitored by real-time PCR

OBJECTIVES

To study the short-term microbiological changes following full-mouth compared with quadrant wise scaling and root planing (FMRP and QRP) as well as long-term effects.

METHOD

Twenty patients with chronic periodontitis were randomized into a test group treated in two sessions with subgingival scaling and root planing within 24 h (FMRP) and a control group treated quadrant by quadrant in four sessions at intervals of one week (QRP). Microbiological samples were taken in the two deepest pockets of the maxillary right quadrant immediately before treatment and after 1 day, 1, 2, 4, 8, 12, and 24 weeks. The samples were evaluated by real-time PCR for quantification of Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum ssp., Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, and Tannerella forsythia as well as for total bacterial counts (TBC).

RESULTS

Treatment resulted in a TBC median log reduction of 0.75 (FMRP) and 0.72 (QRP). There were no differences between groups either for the short term (1 day-4 weeks) (analysis of variance: p=0.3150) or for long term (4-24 weeks) (analysis of variance: p=0.9671). Likewise, no differences were detected for selected target bacteria.

CONCLUSION

The results of the present study showed similar microbiological outcomes following both treatment modalities.

Clinical outcomes of quadrant root planing versus full-mouth root planing

OBJECTIVES

To determine the clinical effects of full mouth compared with quadrant wise scaling and root planing.

METHOD

Twenty patients with chronic periodontitis (> or = 2 teeth per quadrant with probing pocket depths (PPD) > or = 5 mm and bleeding on probing (BOP) were randomized into a test group treated in two sessions with subgingival scaling and root planing within 24 h (full-mouth root planing (FMRP)) and a control group treated quadrant by quadrant in four sessions in intervals of 1 week (quadrant root planing (QRP)). PPD, relative attachment level (RAL) and BOP were recorded at baseline, 3 and 6 months.

RESULTS

Analysing first quadrant data, in moderately deep pockets (5 mm < or = PPD < 7 mm) there was no evidence for a difference (FMRP-QRP) between both groups for PPD reduction (mean: -0.128 mm; CI: [-0.949, 0.693]; p=0.747), RAL gain (mean: 0.118 mm; CI: [-0.763, 1.000]; p=0.781), and BOP reduction (mean: -20.1%; CI: [-44.3, 4.2]; p=0.099). Likewise, no significant differences between treatments were found for initially deep pockets (PPD > or = 7 mm), neither for first quadrant nor for whole mouth data.

CONCLUSION

The results of the present study demonstrated equally favourable clinical results following both treatment modalities.

Comparison of culture and real-time PCR for detection and quantification of five putative periodontopathogenic bacteria in subgingival plaque samples

OBJECTIVES

Bacterial cultivation is a well-established method for analyzing plaque samples. Real-time polymerase chain reaction (PCR) is a novel rapid method for the identification and quantification of periodontopathogenic bacteria that has been recently introduced. In this study, we compared real-time PCR with conventional anaerobic cultivation.

METHOD

A total of 78 subgingival plaque samples were harvested from pockets > or =5 mm in 22 patients with advanced chronic periodontitis and immediately transferred into transport medium. Aliquots were evaluated with species-specific probes by real-time PCR (meridol Perio Diagnostics, GABA) and anaerobic bacteria culture on selective media for the detection of Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia and Tannerella forsythensis. The analysis was performed by two separate, blinded examiners.

RESULTS

When real-time PCR was compared with the culture method (golden standard) for the detection of putative periodontopathogenic bacteria, the sensitivity and specificity for A. actinomycetemcomitans were 67% and 100%, respectively (kappa: 0.79); for F. nucleatum 73% and 53%, respectively (kappa: 0.21); for P. gingivalis 94% and 84%, respectively (kappa: 0.77); for P. intermedia 33% and 94%, respectively (kappa: 0.26) and for T. forsythensis 92% and 56%, respectively (kappa: 0.51). Spearman's correlation coefficients for the quantitative results of both methods were 0.82 for A. actinomycetemcomitans, 0.33 for F. nucleatum, 0.83 for P. gingivalis, 0.38 for P. intermedia and 0.67 for T. forsythensis.

CONCLUSION

Overall, the agreement between both test methods was excellent for A. actinomycetemcomitans and P. gingivalis, fair for T. forsythensis and poor for F. nucleatum and P. intermedia. The discrepancies in the results may be explained by the inability of cultivation methods to distinguish between close related taxa, and the problems of keeping periopathogenic bacteria viable, which is required for standard cultivation.

Clinical and microbiological effects of topical subgingival application of hyaluronic acid gel adjunctive to scaling and root planing in the treatment of chronic periodontitis

BACKGROUND

Hyaluronic acid (HA) has shown anti-inflammatory effects in gingivitis therapy. The potential benefits of local subgingival application of HA adjunctive to scaling and root planing (SRP) were evaluated in this study.

METHODS

Twenty patients with chronic periodontitis were included in this split-mouth study. Sulcus fluid flow rate (SFFR) and sulcus bleeding index were monitored at baseline and after 1, 2, 3, 4, 5, 6, and 12 weeks; probing depth and clinical attachment level were monitored at baseline and 6 and 12 weeks. Subgingival plaque samples were also taken at these same three appointments to determine the presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Treponema denticola. All patients were treated with full-mouth scaling and root planing (SRP); in addition, an HA gel was administered subgingivally in the test sites every week for 6 weeks.

RESULTS

An improvement of all clinical variables was observed (P < 0.05) in both groups. Clinically, no difference between test and control sites could be found. No difference between test and control sites was seen in the tested microorganisms.

CONCLUSIONS

No clinical or microbiological improvement was achieved by the adjunctive use of HA gel compared to SRP alone. Only SFFR was affected by the use of HA in terms of a more rapid reduction of SFFR in the test sites.

Assessment of root curvature and distance using computed tomography

The safety and efficacy of subgingival root surface instrumentation may be enhanced by optimized adaptation between instrument and treated surface. Thus, detailed knowledge of root geometry may allow advances in instrument design. The aim of this study was therefore to measure root radii of various tooth types as well as distances between tooth roots using computed tomography. Two hundred sixteen teeth in eight patients were studied, with cross sections of teeth at the level of the cemento-enamel junction (CEJ) being regarded as ellipses. The maximum radii of ellipses were calculated and averaged for each tooth surface within various tooth groups. In addition, the spacing between roots at CEJ level and 5 mm below the CEJ was measured. Mean radii varied from 1.09+/-0.50 mm (lower incisor, lingual) to 13.7+/-0.96 mm (upper molar, mesial). Radii of 1 mm to 6 mm were most frequently found at buccal, palatal, and lingual surfaces, whereas the majority of radii were between 2 mm and 11 mm at mesial and distal sites. Root distance varied between 1.04+/-0.49 mm (lower incisors, CEJ level) and 2.81+/-1.70 mm (lower molars, 5 mm below CEJ). The curvature of an instrument for root surface instrumentation should correspond to a radius of at least 11 mm to achieve maximum adaptation to the treated surface, and the width of the working end should be less than 1 mm to allow sufficient interdental instrumentation.

[The value of high resolution computed tomography (HRCT) in the diagnosis of deep forms of parodontitis]

It is difficult to demonstrate the extent of parodontal bone erosions with conventional radiographic techniques. HRCT makes it possible to demonstrate the alveolar structures without superimposition. 10 patients with parodontitis marginalis profunda were examined by conventional methods and HRCT. Comparison showed considerable superiority of HRCT in respect of demonstrating bone destruction. The absence of superimposition produces excellent demonstration of the roots and shows the bifurcation and trifurcation of teeth; consequently, mapping the position and shape of the root canals is possible and this is an important aid in the planning of parodontal surgical treatment.

[Ultrasonic root cleansing with 0.1% chlorhexidine gluconate as a coolant]

In 10 patients with marginal periodontitis a systemic periodontal treatment approach was employed in which the root surfaces were cleansed by exclusive use of ultrasound. The effect of 0.1% chlorhexidine gluconate as a cooling medium during the application of ultrasound was studied in a cross over design study. PI, GI, SBI and the probing depths at 6 sites per tooth as well as the clinical attachment levels were the parameters for evaluating the treatment effect. An improvement of the clinical findings was observed during initial treatment both in the test and the control group. Except for PI, which was better after chlorhexidine gluconate application, no obvious differences could be found.