International Poster Journal of Dentistry and Oral Medicine, 02/2012

Objective: The aim of the present study was to evaluate the effect of different concentrations of chlorhexidindigluconate (CHX) on microtensile bond strength (mTBS) of two dentin adhesives (Syntac Classic, Optibond All-in-One) in vitro. Methods: Seventy-two extracted third molars were included in this study. All teeth were specially prepared allowing the simulation of dentin perfusion. The specimens were randomly assigned to one of the six groups of fifteen samples each: group S-C: Syntac control group (no CHX-application); group S-0.2: immersion for five minutes in 0.2% CHX prior to bonding with Syntac, group S-5: immersion for five minutes in 5% CHX prior to bonding with Syntac, groups O-C, O-0.2 and O-5 followed the same procedure with Optibond All-in-One as adhesive. MTBS was measured 15 minutes after application of the composite (Tetric Ceram) using an universal testing machine. Results: Statistical analysis showed a significant influence of the used dentin adhesive and the pre-treatment with CHX in different concentrations (p 0.001, ANOVA). The application of 5% CHX before bonding procedure (S-5, O-5) resulted in a significant reduction of mTBS compared to the untreated control groups (S-C, O-C) (p 0.05, Tukeyxs test). Between the 0.2% CHX-groups and the controls, no significant differences could be detected (p 0.05, Tukeyxs test). Pairwise comparison between Syntac and Optibond showed no significant differences after the different pre-treatments (p 0.05, Tukeyxs test). Conclusions: Within the limitations of an in vitro investigation it can be concluded that CHX in high concentrations affected the mTBS of both tested adhesive systems. Keywords: microtensile bond strength, dentin adhesives, CHX, perfused dentin

Now, direct digital lateral cephalogram (DD-LC) is wide spread and routinely used in orthodontic practice. Recently, cone beam computed tomography (CBCT) technology is widely used in orthodontics to acquire 3D information. Many devices are new capable of a large field of view imaging of the skull to include most anthropometric landmarks used in cephalometric analysis. In current clinical practice, the CBCT DICOM image datasets can be reconstructed to generate a 2D CBCT- lateral cephalograms so that conventional measurements can be made and compared with existing 2-D norms. The advantages of using CBCT lateral cephalograms (CBCT-LC) include the ability to digitally reorient the head position after the initial scan in cases in which the patient did not undergo scanning with the proper head position and the ability to enhance the image quality by virtually sculpting away extraneous superimposing skeletal structures that are not relevant to the lateral cephalometric measurement process (for example, vertebrae). All the previous study related to CBCT cephalometry were on ex vivo human skulls, and they may have some potential limitations when using 3D images derived from CBCT data: unable to simulate soft tissue effects of attenuation on image quality which may have allowed easier identification of landmarks. However, there is a lack of data regarding the reliability and precision of measurements obtained from CBCT constructed cephalograms of orthodontic patients. We hypothesize that the precision of measurements obtained from CBCT LC is similar to the precision of measurements obtained from DD-LC using specific orthodontic software and analysis. Keywords: Measurement Precision, Cone Beam Computed Tomography Lateral Cephalogram, Direct Digital Lateral Cephalogram, Reconstructed Cephalogram

Intrusion of the maxillary posterior segment has always been a challenge to the orthodontic community. Definitive intrusion of the maxillary posterior segment is feasible only by means of orthognathic surgery. Miniscrew implants offer a paradigm change in treatment mechanics of intrusion of the posterior segment alleviating extensive surgical management. The following poster highlights the different types of intrusion of the maxillary posterior segment and the their indication. The biomechanics involved in first order, second order and third order control have been enumerated. The disadvantages of each mechanics are put forth. Comparing the different biomechanics in three dimensions of space (first order, second order, thrid order) the ideal appliance system for three dimensional control has been put forth. Keywords: miniscrew, intrusion, posterior segment

The fabrication of full-ceramic-restorations with the Cerec 3D® System (Sirona Dental Systems GmbH, Bensheim) includes the option to consider the occlusal surfaces of the antagonistic teeth in the construction by scanning an interocclusal record. Thereby extensive occlusal adjustments in the patient should be cancelled. The objective of the study was to determine how exactly the interocclusal record passes information to the Cerec 3D® system. The exactness was examined for the simulated clinical situation in mouth as well as the lab situation on gypsum models. Nine scannable materials of different manufacturers were measured in comparison among each other and in comparison to a primarily not scannable material whose surface was conditioned. The interocclusal records were made in stylised antagonistic casts which were mounted in an articulator to simulate the oral situation. These models were measured at first mechanically. The records were evaluated with the Cerec 3D® internal height data. By using a specially developed algorithm (considered the mechanically won data) the precision was calculated. Different proceedings in the production and measurement of the records were executed. The most exact procedure for the simulation of the chairside-treatment is characterised by very low manipulations on the interocclusal record. Trimming the record should be done in situ without demounting from the teeth. Conditioning the neighbouring teeth with scan spray should be extended also on the surface of the record in one step. Thereby the measured divergences to the surface of the original model amount from 1 to 14 µm on average, according to recording material. However, the vertical discrepancies increased between 36 and 98 µm on average when using the interocclusal record on gypsum models. Keywords: accuracy, scannable, cerec, bite registration, interocclusal recording

The current study was to investigate the early shear bonding strength of two types of ‎bonding agents on different tooth substrates and to compare the results by SEM, AFM ‎and microradiography. Bonding strength of two bonding agents; 3M ADPER Single ‎Bond and OptiBond Solo adhesive system Kerr were investigated at three periods on ‎enamel, prepared enamel and prepared dentin of 240 teeth by Universal testing machine. ‎Specimens were tested under SEM for the measurement of embedment of the bonding ‎material into the tubules of the substrate. The same specimens were reevaluated by AFM ‎and micro-radiography. Shear bond strength test found no significant differences among ‎the tissues or adhesive systems. The Single Bond system formed an authentic hybrid layer ‎that can ensure adequate adhesion. OptiBond Solo showed bonding of composite to ‎dentin and enamel reinforced by mechanical interlocks of the hybrid layer. SEM gave the ‎better reliable image to estimate intrusion of the polymer into dentinal tubules. Keywords: shear bond strength, bonding agents, SEM, AFM, 2D optical analyser

Objective: Using methods of geometric morphometrics, the structures responsible for asymmetries in the jaws of adults should be identified and described. Patients and Methods: The study surveyed 242 models of orthodontically untreated adults with a full dentition using a MicroScribe 3DX digitizer. Were selected in the upper jaw 68 measuring points in the lower jaw 73 measuring points of the teeth and apical base. The xyz coordinates were analyzed with MorphoJ 1.01c. The symmetric and asymmetric components were formed by Procrustes transformation, and compared using correlation matrix. The effects of the symmetry and asymmetry-determining factors (principal components analysis, PCA) were visualized by thin-plate splines (TPS). Results: There were symmetrical and asymmetrical components for the upper jaw (Procrustes sum of squares 0.82 to 0.20) and lower jaw (0.84 to 0.23) separated. The correlation matrix showed dependence of the matrices (p = 0.000). In the PCA the first three components showed in the upper jaw a cumulative variance explanation of 49.8% (symmetrical) and 33.7% (asymmetrical) and in the mandible of 46.9% (sym.) and 33.3% (asym.). In TPS the mandibular asymmetric component are visible as lateral movement in the premolar and canine region, in the upper jaw the changes effect mainly the anterior region and the region of the canines. Moreover, the apical base in terms of a transverse asymmetry is altered here. Conclusions: The study showed that methods of geometrical morphometrics have the ability to separate symmetrical and asymmetrical components and quantify their location graphically. There were both quantitatively similar proportions of the jaw asymmetry. Lateral asymmetries seem to be manifest particularly in the canine in both the upper as well as in the mandible. Keywords: geometric morphometrics, orthodontics, dental arch, asymmetry

Objectives: Bar attachments have been established in implant dentistry. Contrary to prefabricated and individual fabricated metal or electroplated matrices semi-precise resin matrices are economical and easy replaceable. Manufacturers offer various retention forces [RF]. The aim of this in vitro study was to analyze and compare retention characteristics of different prefabricated resin matrices in implant dentistry. Methods: 4 bar systems (Dolder-(U-shaped-)bar-attachments [DBA; C&M], parallel-bar-attachment [PBA], snap-bar-attachment [SBA] and resilient-snap-bar-attachment [RSBA; Bredent]) were tested for retention of the corresponding specific resin matrices. For each system patrices were casted using prefabricated acrylic components (Heraenium, Heraeus Kulzer) and torqued to an implant (RN, Straumann). For each system 3 coloured matrices (n=3x10) with different RF (A, B, C) were tested. RF of 3 systems are indicated by the manufacturers (4/6/8N). DBA quotes 'light'/'middle'/'heavy'. In an universal-testing-machine matrices were removed 10 times from the patrices in (v=50mm/min, axial). Force-deflection-graphs were made. If possible mean RF were compared to manufacturer's data and statistically analyzed (p0,05). Results: RF differed within the groups: DBA 3,6±1,8N to 17,6±1,0N, PBA 5,6±0,6N to 7,9±0,8N, SBA 4,2±1,2N to 7,5±1,0N, RSBA 5,8±1,8N to 8,9±1,6N. Comparing manufacturer's data partially significant differences were recorded: PBA 93,3-152,5%, SBA 70-122,5%;RSBA 108,3-145%. Manufacturer's data of RF were different: PBA-matrixA (4N) 6,1N, PBA-matrixB (6N) 5,6N; SBA-matrixA (4N) 4,9N; RSBA-matrixB (6N) 4,2N. Conclusion: RF of the matrices of most systems showed differences to manufacturer's data. Purposeful application of some systems according to RF seems to be doubtful and unpractical. Keywords: implant dentistry, attachments, bar, retention

Background: Periodontitis is initiated by the subgingival occurrence of periodontopathogens. It is triggered by specific host dependent immune response which is influenced by the genetic predisposition. Polymorphisms in the interleukin 1 (IL-1) gene cluster have been suggested to influence the pathogenesis of periodontitis. Patients and methods: A total of 159 periodontitis patients (chronic: n=73, aggressive: n=86) and 89 periodontitisfree controls were included in the study. Polymorphisms IL-1α (rs1800587), IL-1ß (rs16944, rs1143634), IL-1 receptor (rs2234650), and IL-1 receptor antagonist (rs315952) were determined by polymerase chain reaction with sequence-specific primers (PCR-SSP). Subgingival bacterial colonization was assessed using a polymerase chain reaction (PCR)/DNA probe test (micro-Ident®). Haplotype block structure was determined using Haploview 4.2. Statistical analyses were performed applying SPSS 17.0 considering dominant, recessive and codominant genetic models. Results: In this case-control-study no association between genomic variants of the IL-1 gene cluster and the occurrence of severe periodontitis could be shown. Carriers of the rare genotypes of rs1800587 (pcorr.=0.009), rs1143634 (pcorr.=0.009) and composite genotype (rs1800587+rs1143634) (pcorr.=0.031) had a 2-fold higher risk for subgingival occurrence of A. actinomycetemcomitans. In forward stepwise binary logistic regression analyses considering age, gender, smoking, approximal plaque index as potential confounders these significant associations were proven. Conclusions: Despite the genetic background of IL-1 gene cluster could be shown to be associated with subgingival colonization of A. actinomycetemcomitans there is no evidence that it is an independent risk indicator for periodontitis. Keywords: periodontitis, interleukin 1, SNP

The effectiveness of double plate system prompted the author (Osama Al-ali) to develop a fixed double-plate system, Fixed Lingual Mandibular Growth Modification Appliance (FLMGMA), that would not require patient compliance. A PhD Clinical research is now in progress to identify the effects of FLMGMA treatment. The present case report demonstrates description and use of this new Class II corrector. The hard tissue effect was three dimensionally quantified using cone beam computed tomography (CBCT) data. In addition, three dimensional (3D) superimposition was used to display of the overall treatment outcomes qualitatively. The FLMGMA consists of two separate and fixed parts. The maxillary part consists of acrylic button, two retention wires, two retention hooks, advancement loops. The Mandibular part is made in a similar manner to a standard lingual arch but It includes an inclined guiding plane. This new corrector, which represents the fixed version of the removable double-plate system, is aesthetic, cost effective and clinically easy to handle. Keywords: fixed lingual mandibular growth modification appliance (FLMGMA), class II functional appliance, cone beam computed tomography, three dimensional cephalometric analysis, three dimensional superimposition

The mirror finish during the CAM process is not possible yet nevertheless a high gloss surface is unavoidable, and therefore polishing with the aid of a dental hand piece is still important. We examined different parameters during the dental polishing process by ten different dental technicians concerning their individual way to work. How tall are the emerging contact forces, the emerging temperatures? How long does a dental technician take to polish a defined surface area? How is it to the different materials? Four different materials were tested. Three plastic interim arrangements: Zeno CAO temporary PMMA (Wieland Dental & Technik), Profix (Merz), CAD Temp (Vita), and one leucite ceramic Mark II (Vita). Every sample 10x8x2 mm was made out of cerec-blanks. In each case it was used a specific polisher in two graduations. A prepolisher and a mirror finish polisher. The plastic interim arrangements were polished with Technik Polierer medium and fine (EVE), the ceramic with Diapol medium and fine (EVE). The contact pressure was measured by a load cell (Lorenz K13) its measurement rang is 0,01N -10N, the accuracy is 0,5N. The surface temperature in direct nearness to the polishing process was detected by infrared and additionally the warming of the whole sample by direct contact measurement (Testo temp Sensor 845).The average contact force was determined and generated by ten dental technicians with 80 sample runs. It came up to 1.2 N. This study can be used for subsequent researches and standardized test conditions in the material science as an evaluated quantity. Keywords: surface finishing, handpiece, polishing, CAD/CAM, Cerec, force, temperature, roughness

Aim: Numerous investigations have found active metallomatrix proteinase 8 (aMMP-8) to be a relevant inflammatory marker for early stages of periodontal tissue destruction. The first chairside aMMP-8 test just recently entered the market. It was the aim of this prospective, monocenter case-control study to compare the diagnostic accuracy of this chairside test (PerioMarker® aMMP-8 Schnelltest von Chlorhexamed®) with the conventional laboratory method (ELISA). Methods: For this study, 35 periodontally healthy participants, 60 patients who had gingivitis, and 35 periodontitis patients were recruited. In order to differentiate between the groups, the periodontal screening index was applied. Primary variable was the aMMP-8 chairside test result. Secondary variables were aMMP-8 ELISA test results, plaque index, gingivitis index, bleeding on probing, periodontal pocket depths, clinical attachment level. Parameters were recorded at baseline and after therapy. Healthy participants did not receive any therapy; parameter recording took place at baseline and after four weeks. Gingivitis patients received a dental prophylaxis, periodontitis patients received a deep scaling. Both patient groups were recalled 12 weeks after baseline. Positive and negative agreement [%] between test and control methods was calculated as measure of diagnostic accuracy. The agreement between aMMP-8 concentrations and clinical parameters before and after therapy was assessed by means of contingency tables. Results: Positive agreement between both aMMP-8 methods was found in 75.8% (95%-CI 57.7 - 88.9%). Negative agreement was found in 92.8% (95%-CI: 85.7% - 97.0%). In total, the agreement of test results was kappa=0.692 before therapy and kappa=0.693 after therapy. The percentage of positive test results increased strongly from healthy participants to periodontitis patients. Conclusion: The chairside aMMP-8 test is as exact as ELISA to detect increased MMP-8 activity in patients who have gingivitis and periodontitis. Negative test results indicate healthy periodontal conditions. Keywords: biomarker, aMMP8, parodontitis, chairside test