Microarchitectural study of the augmented bone following ridge preservation with a porcine xenograft and a collagen membrane: preliminary report of a prospective clinical, histological, and micro-computed tomography analysis.

Socket preservation using a combination of porcine xenograft and collagen membrane maintains the vertical and horizontal dimensions of the ridge. The aim of this study was to evaluate the microarchitecture of the grafted area by histological analysis and micro-computed tomography. Patients in the test group (group 1; nine patients) underwent socket preservation, while the sockets in the control group (group 2; eight patients) were allowed to heal without preservation. After a 6-month healing period, bone core biopsy samples were obtained and implants were placed in the augmented sites in the test group (12 biopsy samples) and the non-augmented sockets of the control group (12 biopsy samples). Analysis of the biopsy samples obtained from group 1 revealed that particles of the graft were surrounded by newly formed bone in eight cases and by granulation tissue in four cases. Micromorphometric data showed statistically significant differences in several parameters between the microarchitecture of the native bone and the newly formed bone within the augmented sites, which suggests that the xenograft particles interfere with the bony healing of the alveoli.

Antiinflammatory effect of BPC 157 on experimental periodontitis in rats.

The pentadecapeptide BPC 157 has been shown to have anti-inflammatory and wound healing effects on multiple target tissues and organs. The purpose of the present study was to investigate the effect of BPC 157 on inflammation and bone resorption in experimental periodontitis in rats. First the acute effect of BPC was tested on gingival blood flow by laser doppler flowmetry. Then periodontitis was produced by a silk ligature placed around the lower left first molar. Rats were treated with BPC 157 (once daily for 12 days) or vehicle. At day 13, the gingivomucosal tissues encircling the molars were removed on both sides. Inflammation was assessed by Evans blue plasma extravasation technique and by histology. Alveolar bone loss was analyzed by microCT. BPC 157 had no effect on gingivomucosal blood flow. Twelve day ligature caused a significantly increased Evans blue extravasation in the gingivomucosal tissue, histological signs of inflammation, and alveolar bone destruction. BPC 157 treatment significantly reduced both plasma extravasation, histological alterations and alveolar bone resorption. In conclusion, systemic application of BPC 157 does not alter blood circulation in healthy gingiva. Chronic application of the peptide has potent antiinflammatory effects on periodontal tissues in ligature induced periodontitis in rats. Taken together, this proof of concept study suggests that BPC 157 may represent a new peptide candidate in the treatment of periodontal disease.

The influence of root canal shape on the sealing ability of two root canal sealers.

AIM: To evaluate the influence of root canal form on the sealing ability of two root canal sealers. METHODOLOGY: Twenty radiographically confirmed straight and 20 curved root canals were prepared with a stepback hand filing technique. Root canal aberrations created during preparation were determined by the use of double exposure radiographic technique. The prepared canals were filled with lateral condensation of gutta-percha and one or other of two root canal sealers (Pulp Canal Sealer and Sealapex). Leakage along the apical 10 mm of roots was measured with a fluid transport model at 1, 3, 6, 9 and 12-month intervals. RESULTS: There were no statistically significant differences between straight and curved root canals (P > 0.05) for prevalence of root canal transportation. The prevalence of apical transportation was 80% in the straight and 85% in the curved root canals. A complete seal was more frequently observed in straight canals compared with curved canals. Utilizing the pi* index, analysis showed the filling with Sealapex allowed more leakage than Pulp Canal Sealer at 1 year. CONCLUSION: Under the conditions of the study, root canal form influenced short-term sealing ability. In the long-term the seal was affected by the sealer rather than root canal form.

Measurement of periapical pressure created by occlusal loading.

AIM: To develop an in vitro model in which the pressure in the periapical tissues can be measured during loading. METHODOLOGY: Extracted human maxillary central incisors were embedded in resin blocks that had physical characteristics similar to those of bone and periodontal ligament. Each tooth was loaded with 20, 40, 50, 60, 75, 85, 100, 200, 300 and 450 N vertical forces from the incisal edge of the crown on three consecutive occasions. A minute resistor embedded in the periapical space was used to detect apical pressure changes during occlusal loading. The ratio of apical pressure changes (DeltaP) to the loading force changes (DeltaF) was calculated. RESULTS: The periapical pressure detected was in direct proportion to the loading force. The mean value of DeltaP/DeltaF was 5.994 kPa N-1 (SD = 2.04). CONCLUSIONS: Direct proportionality was found between the coronal loading and the apical hydrostatic pressure. The DeltaP/DeltaF ratio determined in this study makes it easier to estimate the apical hydrostatic pressure values during occlusal loading of single-rooted teeth. In this study, the apical pressure generated under occlusal loading was the same magnitude as that estimated with the finite element method.

A comparison of the shaping characteristics of two nickel-titanium endodontic hand instruments.

AIM: The purpose of this study was to compare the shaping characteristics of Ni-Ti K-files and Ni-Ti S-files manipulated by hand. METHODOLOGY: A total of 60 extracted human roots were embedded in resin blocks. The embedded roots were divided into three groups: (i) roots with straight; (ii) apically curved; and (iii) continuously curved canals. Each of the three groups was randomly divided into two subgroups; one subgroup in each group was prepared with Ni-Ti K-files and the other with Ni-Ti S-files. The files were used with a step-back technique and enlarged so that the master apical file was size 30, and the canals were stepped back to size 40. The performance of the files was assessed by the superimposition of projected radiographs taken in bucco-lingual and mesio-distal directions before and after the preparation. The results were analysed statistically using analysis of covariance and Duncan's multiple range test. RESULTS: Although canal preparation using Ni-Ti K-files was quicker, there were no statistically significant differences between file types. The Ni-Ti S-file removed significantly more material at the most coronal level (P < 0.05). There were minor differences between instruments at the apical level. Only in the proximal view of apically curved canals prepared with Ni-Ti S-files was significantly more dentine removed from the outer aspect of the curvature (P < 0.05). At the middle level (wide danger zone) the Ni-Ti S-files removed more dentine from the inner aspect of the curvature in those roots with apically curved canals. CONCLUSIONS: Under the conditions of this study, preparation with Ni-Ti K-files produced more appropriate shapes in roots with apically curved canals than Ni-Ti S-files.

[Mathematical description of human root canal curvatures]. / Az emberi fogak gyökércsatorna-görbületének matematikai leírása.

There is a necessity of a mathematical formula for the description of root canal curvatures. The aim of this study was to give a mathematical description of root canal forms. The measurements of 60 roots were conducted on isometric radiographs taken from the clinical view. Seven points of the imaginary axis were approximated using fourth-degree polynomial functions. Fourth-degree approximation for the description of the shape of root canal curvatures proved to be exact and reliably repeatable. This method may serve the classification of root canal forms as well as the description of the spatial curve of root canals.

A computerized method for mathematical description of three-dimensional root canal axis.

Knowledge of the three-dimensional (3D) morphology of root canals is important for successful endodontic treatment. The objective of the present study was to determine the 3D root canal axis mathematically. Two views (mesiodistal and buccolingual) of digitized images were taken from extracted natural human teeth. Geometric reconstruction to standardize projection geometry was conducted on images. Because 90-degree turn-around image pairs are Monge images of a given root canal, these Monge images were positioned using photogrammetric methods. Each well-ordered axis pair of a given root canal was put into a common coordinate system resulting in 3D polynomial function of the actual root canal. On the basis of the results gained using 10 samples evaluated with the Friedman statistical test, this description seems to be reproducible. The 3D representation of the root canal may help the clinicians in choosing the optimal instruments and shaping techniques. The root canal axis that is described by the 3D function forms a basis for determination of curvature values and torsion values in each of the axis points. Evaluating these values may also yield a new type of classification.

[Comparative microleakage study of two root canal sealants: calcium hydroxide and zinc oxide eugenol]. / Kalcium-hidroxid- és cink-oxid-eugenol-tartalmú gyökértömö paszták összehasonlító szélizárás-vizsgálata.

A quantitative longitudinal study was carried out to compare the amount of microleakage using two different types of root canal sealers on straight and curved root canals. Microleakage was measured just after the setting of the sealer, one month and three months after that using fluid transport model. One month follow up results showed that in straight root canals both the ZOE containing Pulp Canal Sealer and the calciumhydroxide containing Sealapex sealers produced similar microleakage values to that values measured just after the setting of materials. One month follow up measurement resulted higher values in curved canals comparing to the straight ones in case of both the tested materials. Three months follow up measurement demonstrated worse results in the Sealapex groups than the Pulp Canal Sealer groups. With loglinear statistical analysis the following interactions were proved between variables: root canal form/microleakage, root canal form/time laps, and material/microleakage/time laps. Results of the present study are in good agreement with conclusions of recently published other studies, namely calciumhydroxide containing sealers resulted in higher microleakages than ZOE containing sealers.