Biomedical subjects

T Lambrianidis

Publications and source records attributed to T Lambrianidis.

At least 19 recordsLinked to original sources

PubMed2006

Ex vivo study of the efficacy of H-files and rotary Ni-Ti instruments to remove gutta-percha and four types of sealer.

AIM: To compare the efficacy of ProFile rotary Nickel-Titanium (Ni-Ti) instruments and Hedstroem-files (H-files) combined with Gates-Glidden (GG) drills during removal of gutta-percha root fillings used in combination with one of the four representative sealers. METHODOLOGY: Forty-eight single-rooted human teeth, with fully formed apices and straight root canals were used. The root canals were accessed and instrumented using a stepback technique with H-files. They were randomly assigned to four groups and subsequently filled with a combination of lateral and vertical condensation of gutta-percha and one of the following sealers: Roth 811, AH26, Endion and Roekoseal. The root fillings were removed 1 year later, using either H-files in combination with GG drills or the ProFile Ni-Ti system. Teeth were then grooved longitudinally and split. The amount of gutta-percha and sealer remaining on the root canal walls was traced and scored visually with the aid of a stereomicroscope. The scores were analysed and statistically compared with the Kruskal-Wallis test between the ProFile and H-file groups, as well as among the four sealer subgroups. Two samples from each group were studied under the scanning electron microscope to enhance inspection of canal walls and remaining material. RESULTS: Sealer remnants were observed with both techniques mainly in the middle and apical third of the root canal. The ProFile system and the H-files were associated with similar amounts of remaining filling material (P > 0.05). In the cervical third of the root canal all sealer remnants were removed with both techniques. In the middle and apical third AH26 was associated with a statistically significant greater quantity of remnants on the root canal walls with both removal techniques (P < 0.05). Endion, Roth 811 and Roekoseal were associated with approximately the same amount of filling material in the middle third of the root canal (P > 0.05), whereas in the apical third Endion was associated with significantly more remnants of filling material than the other two sealers with either ProFile or H-files (P < 0.05). CONCLUSIONS: None of the methods used for the removal of root fillings was totally effective, especially in the apical third of the root canal.

Dental Cements↗

PubMed2006

Removal efficacy of various calcium hydroxide/chlorhexidine medicaments from the root canal.

AIM: To compare the efficiency of removing calcium hydroxide [Ca(OH)(2)]/chlorhexidine (CHX) (gel), Ca(OH)(2)/CHX (solution) and Ca(OH)(2)/saline pastes with the use of instrumentation and irrigation with sodium hypochlorite and ethylene diamine tetraacetic acid (EDTA) solutions. Moreover the role of the patency file in the cleanliness of the apical third of the root canal was evaluated. METHODOLOGY: Sixty-four human single-rooted teeth with straight canals were used. Root canal preparation was performed with a stepback technique using Hedström (H) files. Teeth were randomly assigned to three groups and subsequently filled with one of the pastes: Ca(OH)(2)/CHX (gel), Ca(OH)(2)/CHX (solution) and Ca(OH)(2)/saline paste. The medicaments were removed 10 days later using instrumentation and irrigation with 1% sodium hypochlorite and 17% EDTA, with or without obtaining patency of the apical foramen with a size 10 H-file. The crowns were removed at the cemento-enamel junction and the roots were grooved longitudinally and split into halves. Images of all halves were acquired with the use of a flatbed scanner. A scoring system of 1 to 4 was used to assess the amount of residue on the cervical, middle and apical third of the canal. Data were subjected to statistical analysis using Kruskal-Wallis and Mann-Whitney tests, with Bonferroni correction, at 95% confidence level (P < 0.05). RESULTS: Remnants of medicament were found in all experimental teeth regardless of the experimental material used and the use of the patency file. When examining the root canal as a whole, Ca(OH)(2)/CHX (gel) paste was associated with significantly larger amount of residue, whereas the Ca(OH)(2)/CHX (solution) paste was associated with less amount (P < 0.05) than the other two medicaments with or without the use of a patency file. CONCLUSIONS: None of the techniques used in this study removed the inter-appointment root canal medicaments effectively; the use of the patency file facilitated removal of more of the medicament in the apical third of those straight canals.

Calcium Hydroxide↗

PubMed2004

Healing of a radiolucent periradicular lesion with periradicular radiopacity.

Periradicular radiopacities that reveal the existence of sclerotic bone are less common than periradicular radiolucencies. Replacement of a radiolucent periradicular area by sclerotic bone after endodontic treatment is not very often reported and may be confused with condensing osteitis. An unusual case is presented of sclerotic bone formation after endodontic treatment of a first mandibular molar with initial diagnosis of apical periodontitis.

Adolescent↗

PubMed2002

Effect of calcium hydroxide as a supplementary barrier in the radicular penetration of hydrogen peroxide during intracoronal bleaching in vitro.

AIM: To examine pH changes in the cervical external root surface, when calcium hydroxide was used as a supplementary barrier to the protective base material during intracoronal bleaching. METHODOLOGY: Twenty-eight single-rooted human premolars extracted for orthodontic reasons were instrumented with K-Flex files, obturated with gutta-percha and subjected to thermocatalytic bleaching. The teeth were divided into four groups. In group A, a glass-ionomer cement barrier was placed at the cemento-enamel junction (CEJ) level and in group C, the barrier was placed 1 mm apical to the CEJ. In groups B and D, Ca(OH)2 was placed in contact and apical to the glass-ionomer cement at the CEJ and 1 mm apical to the CEJ, respectively. The teeth were placed in vials containing distilled water and the pH values of the medium surrounding the teeth were recorded after 1, 2, 4, 10 and 15 days, following renewal of the medium. RESULTS: The pH in the medium became acidic in all groups. No statistically significant differences existed between groups for all the experimental days (P = 0.790). CONCLUSION: The placement of Ca(OH)2 as a supplementary barrier during intracoronal bleaching did not have a significant effect in reversing the acidic pH created at the external root surface in vitro. Its potential effect during these procedures in vivo needs to be further investigated.

Adult↗

PubMed2002

Clinical relevance of standardization of endodontic files dimensions according to the ISO 3630-1 specification.

The aim of this study was to examine the current status of standardization of endodontic instruments. Measurements of instrument dimensions were conducted on stainless steel H- and K-files (sizes 08-40), as well as on rotary-driven nickel titanium (NiTi) files (sizes 15-40), to determine the incidence and degree of deviation from ISO 3630-1, 1992 specification. In addition, the dimensions of sets of H- and K-files (sizes 08-25) were measured to identify discrepancies in dimensions among instruments within the same size per manufacturer. The percentage of difference in width were used to determine the graduation from each size to the next. None of the files tested complied with the ISO nominal size. All files were within the ISO tolerance limits. However, under such tolerance limits, there is a high possibility of either sizes overlapping or of great differences between two sequential sizes. These results may explain the clinical difficulty found in negotiating narrow and curved canals and may establish the need for a more comprehensive approach on the evaluation methods used in root-canal instrument dimension specifications.

Dental Instruments↗

PubMed2001

Evaluation of periapical radiographs in the recognition of C-shaped mandibular second molars.

AIM: The purpose of this study was to evaluate in a blind trial the efficacy of radiographs to recognize C-shaped mandibular second molars and to determine the incidence of this entity amongst second mandibular molars treated in the Department of Endodontology at the School of Dentistry of the University of Thessaloniki during a seven-year period (1989 - 95). METHODOLOGY: A total of 480 clinical records of root treated mandibular second molars were reviewed. The preoperative, working length, and final radiograph of each tooth alone and in combination were examined in groups as follows: group 1 (preoperative radiographs only), group 2 (working length radiographs), group 3 (final radiographs), group 4 (preoperative and working length radiographs), group 5 (preoperative and final radiographs) and group 6 (all three radiographs). The efficacy of each combination to identify the C-shaped cases was evaluated based on the interpretation of three experienced dentists looking simultaneously at each case. Films were examined on a viewer using a magnifying glass and allowing a two-week interval between groups. Results were compared with the clinical diagnoses stated on the patients' records (group 7). RESULTS: The review of clinical records revealed that 4.58% of second molars had C-shaped canals. Radiographic interpretation was overall more effective when based on film combinations (groups, 4, 5, and 6) than on single radiographs. Amongst the latter, working length radiographs were more helpful than the preoperative and final ones. Preoperative radiographs were the least effective in diagnosing C-shaped cases. CONCLUSIONS: Simultaneous interpretation of preoperative, working length and post-treatment radiographs is important when attempting to diagnose a C-shaped configuration.

Dental Pulp Cavity↗

PubMed2001

The effect of maintaining apical patency on periapical extrusion.

Thirty-three human maxillary incisors were secured in the openings of a glass vial. Root canals were instrumented to the apical constriction with a step-back technique and a patency file was not used throughout the root canal preparation. The irrigant, 1% NaOCl, was delivered by means of a plastic syringe with a 23-gauge needle and the overflow was suctioned with an aspirator. The total volume of irrigant used was 10 ml. Apically extruded debris and NaOCl were measured. The apical constriction was then deliberately enlarged. With a step-back technique a new 'apical constriction' was created, coronally to the original one. A patency file was again not used, and irrigation was identical to the that used during the initial root canal preparation. Extruded debris and NaOCl in each bottle were again measured. Results indicated that there was significant difference in the amounts of extruded material before and after the enlargement of the apical constriction with greater extrusion when the constriction remained intact.

Anti-Infective Agents, Local↗

PubMed2000

Immunologic evaluation of dental patient with history of hypersensitivity reaction to sodium hypochlorite.

A 12-year-old girl, with a previous history of bronchial reaction and contact dermatitis to sodium hypochlorite, was referred for root canal treatment. Complete immunologic evaluation revealed a mild hypersensitivity condition, as it was assessed by the RAST investigation to different allergens and the DTH reactivity expressed though migration inhibition test. The absence of a serious immunologic disregulation in the patient's immunologic profile justified the term 'non-allergic hypersensitivity' to sodium hypochlorite to describe the condition.

Bronchial Hyperreactivity↗

PubMed2000

Factors associated with root canal ledging during instrumentation.

The purpose of this study was to identify the presence of a ledge in 141 cases treated in an undergraduate clinic and in 103 cases treated by endodontists, and to identify the clinical factors associated with ledging. A total of 626 root canals were examined and the factors analyzed were canal location, tooth number and canal curvature. The results indicated that 51.5% of the canals treated by students had been ledged, whereas the percentage was 33.2% for intact pulp cavities treated by endodontists and 40.6% in cases of endodontic retreatment. Canal location was found to have an effect on the incidence of ledging as the mesiobuccal, mesiolingual and distal buccal root canals exhibited a significantly higher ledge incidence rate than the distal and palatal root canals. Canal curvature was the most significant variable affecting the incidence of ledging.

Dental Pulp Cavity↗

PubMed2000

A case report of a compound odontoma causing delayed eruption of a central maxillary incisor: clinical and microscopic evaluation.

A case of a compound odontoma caused delayed eruption of a central incisor in the maxilla is presented with clinical, radiographic, and microscopic findings. The odontoma was surgically removed and microscopic examination showed a lot of crown-like structures in a very irregular form, some of which were fused to each other at their apical parts. Enamel and pre-enamel were totally abnormal, whereas the inside of the pulp chamber tissue did not present any histological sign of functional tissue. The most homogeneous tissue was dentin. The removal of the odontoma was followed by a rapid eruption of the impacted central incisor.

Child↗

PubMed1999

Removal efficiency of calcium hydroxide dressing from the root canal.

The aim of this study was to investigate whether differences in the composition of calcium hydroxide (Ca(OH)2) preparations influence the removal efficiency of irrigation solutions used in combination with filing of the canal. Three Ca(OH)2 preparations were used: Calxyl, Pulpdent paste, and chemically pure Ca(OH)2 mixed with distilled water. Fifty-one single-rooted extracted human teeth were prepared with a step-back technique and divided into groups A, B, and C. In each group, 15 teeth were assigned to each Ca(OH)2 preparation while the remaining two served as positive and negative controls. Each group of treated teeth was divided into three subgroups of five teeth each: subgroup I--canals were irrigated with saline, filed with a #25 file, and finally flushed with saline; subgroup II--canals were irrigated with NaOCl, filed with a #25 file, and finally flushed with NaOCl; and subgroup III--canals were irrigated with NaOCl, filed with a #25 file, and finally flushed with tetrasodium EDTA. Canal sections were then photographed, and the percentage ratios of Ca(OH)2 coated area to the total canal surface area were calculated by image processing analysis. Results revealed: (a) none of the methods efficiently removed all dressing from the walls, and (b) concentration of the paste used had little effect on the efficacy of the methods applied for the removal of the dressing. Excipients (i.e. methylcellulose contained in Pulpdent) possibly effect retention of Ca(OH)2.

Calcium Hydroxide↗

PubMed1998

In vitro evaluation of the cytotoxicity of a bleaching agent.

Cell cultures of L929 and BHK21/C13 cells were used to evaluate the toxicity of a newly introduced bleaching agent (Colgate Platinum) compared to hydrogen peroxide, an established bleaching agent. The cell reaction was determined by a quantitative technique at 24 h and 72 h. Both bleaching materials had a dose-dependent effect on cell viability. Concentrations of hydrogen peroxide causing a 50% decrease in cell number (50% inhibition dose-ID50) were calculated as 0.00034% after 24 h and 0.00001% after 72 h in L929 cells. The ID50 of hydrogen peroxide was found to be 0.00016% after 24 h and 0.00007% after 72 h in BHK21/C13 cells. The ID50 of Colgate Platinum was 0.00074% after 24 h and 0.00045% after 72 h in L929 cells and 0.00055% after 24 h and 0.00024% after 72 h in BHK21/C13 cells. The results showed that, in vitro, both bleaching agents were cytotoxic to fibroblasts and the new bleaching agent was less toxic than hydrogen peroxide.

Animals↗

PubMed1997

3D reconstruction of two C-shape mandibular molars.

Two mandibular second molars, with an indication of C-shape morphology were processed for 3-D reconstruction. After serial cross sectioning, photographs of the sections were digitized and by using surface representation, 3D reconstruction was achieved. The first molar as the 3D reconstruction showed was single rooted with one C-shaped root canal with two foramens, while the second one was double rooted with two root canals, one C-shaped and one thin, having a common foramen.

Anatomy, Cross-Sectional↗

PubMed1996

Role of cementoenamel junction on the radicular penetration of 30% hydrogen peroxide during intracoronal bleaching in vitro.

Intracoronal bleaching of nonvital, teeth with 30% hydrogen peroxide is occasionally associated with external cervical root resorption. The exact mechanism by which bleaching induced root resorption occurs is not yet fully understood. The relationship of cementum to the enamel at the cementoenamel junction may have clinical significance. Seventeen single rooted human mandibular premolars extracted atraumatically for orthodontic reasons were used. The radicular hydrogen peroxide penetration in each tooth was measured in vitro by an indirect colorimetric method. Thereafter, the teeth were examined with a scanning electron microscope to determine the type of the cementoenamel junction. It was found that the radicular penetration of 30% hydrogen peroxide was related to the type of cementoenamel junction.

Adult↗

PubMed1996

Accidental swallowing of endodontic instruments.

Swallowing or aspiration of a foreign body is a complication that may arise from any procedure in the oral cavity performed without the use of a rubber dam. Two cases of swallowed endodontic instruments and possible complications are presented. Emphasis is given in the discussion on the early diagnosis and treatment and primarily on prevention with the use of rubber dam, an absolute essential during endodontic treatment.

Adolescent↗

PubMed1993

Inductive effect of native dentin on the dentinogenic potential of adult dog teeth.

Autogenous dentinal matrix was exposed to the pulp cells of adult dogs in order to determine whether the mature pulp cells possess the ability to differentiate into odontoblast-like cells as a direct response to known inductive influences. The pulps of molars, premolars, and canines of three dogs (2 to 4 yr old) were mechanically exposed through buccal class V cavities. Pieces of demineralized or native dentin and predentin were implanted in the pulp sites for periods of 2 to 6 wk. The reactions were analyzed by light microscopy. Induction of dentin formation was observed only after native dentin implantation; either as early response to exposure of predentinal surfaces or around mineralized dentin after 3 postoperative wk. Encapsulation by fibrous connective tissue or matrix degradation was seen around demineralized dentin implants. A characteristic enhancement of circumferential pulpal dentin deposition around the implantation site was demonstrated after native dentin exposure to light and scanning electron microscopic examination. These data indicate that specific inductive influences given by the native but not the acid-conditioned dentin, when it is exposed to the pulp environment of adult teeth, are able to direct differentiation of odontoblast-like cells and to enhance the biosynthetic activity of primary odontoblasts.

Animals↗

PubMed1992

Sealing ability of sectional injection thermoplasticized gutta-percha technique with varying distance between needle tip and apical foramen.

The purpose of this investigation was to evaluate the influence of the distance of the needle tip from the apical foramen on the apical seal and the length control of the root filling material when thermoplasticized gutta-percha is injected using a sectional injection technique. Ninety-nine human single-rooted mandibular incisors and permanent premolars with straight canals were divided into three equal Groups A, B and C. In Group A the teeth had relatively the wider root canal, in Group C the narrowest, while in Group B root canal size was intermediate. The root canals of all teeth were prepared with a step-back technique. Roots of Group A were instrumented to a Size 70 4 mm short of the working length, while roots of Groups B and C to a Size 70 6 mm and 8 mm short of the working length, respectively. The teeth of all groups were covered with aluminium foil and embedded in acrylic blocks. After the placement of sealer (Roth 811) the root canals of all teeth were obturated with injection-molded thermoplasticized gutta-percha using a three-stage sectional technique. The roots remained in India ink for three days and then cleared by successive immersion in nitric acid, ascending grades of alcohol and finally in xylene. The linear dye penetration and the linear apical underextentionion of the root canal filling were measured by two independent examiners under a stereo microscope. There was no significant difference in the linear dye leakage between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Bicuspid↗

PubMed1991

The effect of citric acid treatment on periodontal healing after replantation of permanent teeth.

The aim of this study was to evaluate the effect of surface demineralization on the healing of 120 replanted teeth in fifteen 8- to 16-month-old dogs. Replanted teeth were divided into two groups (A and B). In group A, teeth were replanted following planing of the entire root surface. In group B, teeth were replanted following planing and surface demineralization with citric acid. Replanted teeth were splinted for 7 days, and observation periods were 3, 14 and 56 days. A total of 95 teeth and their surrounding tissues were examined histologically under a light microscope. Histological examination of specimens 3 days after replantation revealed that initial reunion between the root and the alveolar periodontal ligament fibres was via a fibrin-like network in both groups. Fourteen days after replantation histological observations showed superior healing in group B with regard to epithelial condition, periodontal ligament fibre reattachment to the root surface, resorption and functional arrangement of the periodontal ligament fibres. By 56 days after replantation, healing was superior in group A; group B was characterized by severe inflammatory and replacement resorption. These results indicated that surface demineralization had an initial positive effect, but later led to impaired healing.

Animals↗