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Human Premolars (human + premolar)
Selected AbstractsStudies on dentin grafts to bone defects in rabbit tibia and mandible; development of an experimental modelDENTAL TRAUMATOLOGY, Issue 1 2009Lars Andersson This property may possibly be used as an alternative or supplement to bone grafting to defective areas after trauma prior to treatment with osseointegrated implants. Hence, the objective of this study was to investigate if dentin can be used as a graft in bone defects in an experimental rabbit model. Materials and Methods:, Eight New Zealand White Rabbits were used to prepare bone cavities either in the angle of the mandible or tibia. Six of the eight tibial and six of the eight mandibular bone defects were filled with dentin blocks from human premolars which were extracted for orthodontic treatment. Two mandibular and two tibial bone cavities were used as controls and all the rabbits were sacrificed after 3 months. Radiographic and histological examinations were performed. Results:, There was a difference in healing pattern between the mandibular and tibial defects. In the mandible, the dentin blocks were resorbed to a larger extent and more often surrounded by fibrous tissue, probably due to the fact that the dentin blocks were mobile because of the thin mandibles and muscular activity in that area. Only some dentin blocks were ankylosed with the mandibular bone. In the tibia however, all dentin blocks were fused to bone over a large area. Osseous replacement resorption was seen. In control cavities, bone formation was seen but was never complete. No signs of inflammatory changes were seen in any fused grafts. Conclusions:, Dentin grafts have a potential to be incorporated in bone without inflammation and can be used as bone inducer and later replaced by bone. Thus, rabbit tibia served as a better model for further studies of this phenomenon when compared to the mandible. [source] Comparison of bonding efficacy of an all-in-one adhesive with a self-etching primer systemEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2004Tomoko Abo The aim of this study was to compare the bonding efficacy of an all-in-one adhesive with that of a self-etching primer system by measuring microleakage after thermocycling and the microtensile bond strength (,TBS) to enamel and dentin. Circular class V cavities along cement,enamel junctions were prepared in 20 extracted human premolars. Each 10 teeth were bonded with either AD Bond (AD) or Clearfil SE Bond (SE), and filled with a resin composite (Charisma). After thermocycling and staining with 0.5% basic fuchsin, the microleakage at the coronal and apical walls was evaluated using longitudinal sections. In addition 20 premolars were used to measure ,TBS at 24 h after bonding for these adhesives to enamel and dentin that corresponded to the coronal and apical walls of the class V cavities. AD showed more microleakage than SE in the coronal walls, but there was less microleakage in the apical walls and no difference in apical leakage between the two adhesives. ,TBS (SD) in MPa to enamel and dentin were 25.2 (7.3) and 68.3 (9.4) for AD, and 35.8 (7.4) and 76.4 (7.8) for SE, respectively. AD gave a lower ,TBS to enamel than did SE. The results suggested that the poor adaptation at the coronal wall in AD might be caused by the lower bond strength to enamel. [source] Micro-computed tomography of tooth tissue volume changes following endodontic procedures and post space preparationINTERNATIONAL ENDODONTIC JOURNAL, Issue 12 2009O. H. Ikram Abstract Aim, To compare the volume of hard tooth tissue lost after caries removal, access cavity preparation, root canal preparation, fibre post space and cast post preparation in carious premolar teeth. The null hypothesis tested was that there is no difference between the volumes of hard tooth tissue lost expressed as a percentage of the preoperative hard tooth tissue volume, after each operative procedure. Methodology, Twelve extracted human premolars with mesial or distal carious cavities penetrating into the pulp chamber were selected. Teeth were scanned using a microCT scanner. After each operative procedure the loss of hard tooth tissue volume was measured. The data were statistically analysed using one-way analysis of variance and Fisher's PLSD test with statistical significance set at , = 0.01. Results, The percentage of preoperative hard tooth tissue volume lost after caries removal was 8.3 ± 5.83, after access cavity preparation the loss of volume reached 12.7 ± 6.7% (increase of 4.4%). After root canal preparation, fibre post space and cast post preparation the hard tissue volume lost reached, 13.7 ± 6.7 (increase of 1%), 15.1 ± 6.3 (increase of 1.4%) and 19.2 ± 7.4 (increase of 4.1%) respectively. Each procedure performed after caries removal significantly increased (P < 0.01) the amount of hard tissue volume lost with the exception of the root canal preparation. Conclusions, Access cavity and post space preparation are the procedures during root canal treatment which result in the largest loss of hard tooth tissue structure. Cast post space preparation causes a larger loss of tooth structure than fibre post space preparation. This should be taken into account when planning root canal treatment and restoration of root filled teeth that are to be restored with cuspal coverage restorations. [source] Mechanism and control of tooth eruption: overview and clinical implicationsORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 2 2009WR Proffit Structured Abstract Authors,,, Proffit WR, Frazier-Bowers SA Objectives,,, To review pre- and post-emergent eruption, with particular emphasis on distinguishing isolated molar ankylosis from primary failure of eruption (PFE) and genetic considerations in eruption problems. Material and Methods,,, Radiographic review of eruption failure patients; animal and human experiments; high precision observations of movements of erupting teeth. Results,,, In pre-emergent tooth eruption, the controlling element is the rate of resorption of overlying structures. A path is cleared, and then the erupting tooth moves along it. This has clinical importance in recognizing the cause of eruption problems, particularly PFE, in which all teeth distal to the most mesial involved tooth do not erupt or respond to orthodontics. In our study of by far the largest sample of PFE cases yet reported, familial cases of PFE accounted for approximately ¼ of all cases examined. Candidate genes now are being evaluated. In post-emergent eruption, control seems to be light forces of long duration that oppose eruption, rather than heavy forces of short duration such as those during mastication. Studies of human premolars in their passage from gingival emergence to the occlusal plane show that in this phase eruption occurs only during a few hours in the early evening. The critical hours for eruption parallel the time that growth hormone levels are highest in a growing child. In this stage intermittent force does not affect the rate of eruption, but changes in periodontal blood flow do affect it. [source] A comparative histological analysis of human pulp following direct pulp capping with Propolis, mineral trioxide aggregate and DycalAUSTRALIAN DENTAL JOURNAL, Issue 1 2010A Parolia Abstract Background:, Permanent teeth pulp exposures have traditionally been treated with calcium hydroxide pulp capping. The aim of this study was to investigate the response of human pulp tissue which were mechanically exposed to a new material, Propolis and compare it with two existing and commonly used pulp capping agents (mineral trioxide aggregate and Dycal). Methods:, Thirty-six intact human premolars were mechanically exposed. Teeth were divided into six groups of 6 teeth each and were capped with Propolis, mineral trioxide aggregate and Dycal. Final restoration was done with posterior composite resin using light cured glass ionomer cement as a liner. The teeth were then extracted on the 15th or the 45th day and processed for histological evaluation. Results:, Differences in inflammatory response and dentine bridge formation of the exposed pulp to the three different materials were statistically calculated using chi-square test and were found to be non-significant. There was more pulp inflammation in teeth treated with Dycal than with Propolis and MTA on the 15th as well as on the 45th day. Propolis and MTA showed bridge formation in more teeth, and the bridges were in closer proximity to pulp capping material than teeth treated with Dycal on the 45th day. Conclusions:, The response of pulps to Propolis as a pulp capping agent was comparable to MTA and Dycal. [source] | ||||||||||