T and B Cells in Periodontal Disease: New Functions in A Complex Scenario.

Periodontal disease is characterised by a dense inflammatory infiltrate in the connective tissue. When the resolution is not achieved, the activation of T and B cells is crucial in controlling chronic inflammation through constitutive cytokine secretion and modulation of osteoclastogenesis. The present narrative review aims to overview the recent findings of the importance of T and B cell subsets, as well as their cytokine expression, in the pathogenesis of the periodontal disease. T regulatory (Treg), CD8+ T, and tissue-resident γδ T cells are important to the maintenance of gingival homeostasis. In inflamed gingiva, however, the secretion of IL-17 and secreted osteoclastogenic factor of activated T cells (SOFAT) by activated T cells is crucial to induce osteoclastogenesis via RANKL activation. Moreover, the capacity of mucosal-associated invariant T cells (MAIT cells) to produce cytokines, such as IFN-γ, TNF-α, and IL-17, might indicate a critical role of such cells in the disease pathogenesis. Regarding B cells, low levels of memory B cells in clinically healthy periodontium seem to be important to avoid bone loss due to the subclinical inflammation that occurs. On the other hand, they can exacerbate alveolar bone loss in a receptor activator of nuclear factor kappa-B ligand (RANKL)-dependent manner and affect the severity of periodontitis. In conclusion, several new functions have been discovered and added to the complex knowledge about T and B cells, such as possible new functions for Tregs, the role of SOFAT, and MAIT cells, as well as B cells activating RANKL. The activation of distinct T and B cell subtypes is decisive in defining whether the inflammatory lesion will stabilise as chronic gingivitis or will progress to a tissue destructive periodontitis.

Novel keratin preparation supports growth and differentiation of odontoblast-like cells.

AIM: To fabricate a keratin hydrogel, characterize its functionality as a biomaterial and investigate the effects of keratin on growth and differentiation of odontoblast-like cells. METHODOLOGY: Keratins were extracted from sheep wool using a well-established technique. The extracted proteins were purified by dialysis, quantified by gel electrophoresis, mass spectrometry, amino acid analysis and inductively coupled mass spectrometry. The microstructure of the fabricated keratin hydrogels was studied by scanning electron microscopy, flow characteristics by rheometer, hydrolytic stability and cytocompatibility by Live/Dead(®) cell assay. Furthermore, the influence of keratin on odontoblast-like cells (MDPC-23) was assessed to confirm their bioactivity at different dilutions. Cell proliferation was studied using alamarBlue(®) assay and differentiation by alkaline phosphatase enzyme activity, alizarin red staining and calcium quantification, reverse transcription polymerase chain reaction (rt-PCR) and immunocytochemical staining for dentine matrix protein- 1 (DMP-1) expression. anova with Tukey's tests was performed for statistical comparison. RESULTS: The characterized hydrogel was injectable with a highly porous architecture that underwent slow degradation, and its cytocompatibility was statistically equivalent to collagen hydrogel (P > 0.05). Cell proliferation and differentiation were enhanced at the optimal keratin concentration of 0.1 mg mL(-1) . At this concentration, the influence of keratin on cell differentiation was demonstrated by marked elevation in alkaline phosphatase activity (P < 0.05), calcium deposition (P < 0.01), gene expression (P < 0.01) and positive immunostaining for DMP-1. CONCLUSION: The presence of keratin enhanced odontoblast cell behaviour. Keratin hydrogels may be a potential scaffold for pulp-dentine regen-eration.

Collagen-like peptide sequences inhibit bacterial invasion of root dentine.

AIM: To investigate the effects of peptides derived from the sequence of collagen to inhibit penetration of human or bovine dentine by species of streptococci and enterococci. METHODOLOGY: Blocks of human or bovine root dentine were infected for 14 days with bacterial cultures, in the presence or absence of various collagen-like peptide sequences. Invasion of dentinal tubules was determined from microscopic images of histochemically stained dentine thin sections. Extent of invasion was expressed as tubule invasion index (TI), or tubule invasion factor (TIF) which, in addition to the density of invasion, took into account the depth of invasion. Data were analysed by two-way anova. RESULTS: Streptococcus gordonii, Streptococcus mutans and Enterococcus faecalis were associated with heavy invasion (TI >2.5, TIF >4) of human or bovine root dentinal tubules, with E. faecalis being the most penetrative. Incorporation of peptides Gly-Pro-Ala or Gly-Pro-Hyp into the in vitro model system significantly reduced (P < 0.05) dentine invasion by the three species of highly invasive organisms. Inhibition of bacterial invasion by the peptides was dose dependent, and the peptides did not inhibit bacterial growth in culture. CONCLUSION: Specific collagen-like peptide sequences inhibited the invasion of dentine in vitro by a range of oral bacteria. The peptides likely act as competitive inhibitors blocking bacterial collagen receptors and could potentially allow for target-specific control of dentine infections.

Oral health of older people admitted to hospital for needs assessment.

OBJECTIVES: To describe the clinical oral health status, treatment needs and oral-health-related quality of life (OHRQoL) of older people admitted to older persons' wards at Dunedin Public Hospital due to a sudden worsening of their general health. Participants and methods: A systematic oral assessment was undertaken for a consecutive case series of 200 patients (59.5% female; mean age 82.6 years, sd 6.6) admitted to older person's wards at Dunedin Public Hospital. The Oral Health Impact Profile-20 (OHIP-20) was used to assess OHRQoL. RESULTS: One in three (36.0%) had been living independently at home prior to admission, and over half (55.0%) had been admitted for a medical reason which required assessment. Half (50.0%) of the participants were dentate (with an average of 16.8 teeth). There was an average of 1.9 decayed teeth present in the dentate group; 70.7% of individuals required restorations or extractions, and about 90% required only simple scaling of the teeth and prophylaxis. A reline or a replacement denture were required by three-quarters of those with dentures. Almost two-thirds of participants did not have a regular dentist, and fewer than one in three had made a dental visit in the previous year. One in six described their oral health as 'fair' or 'poor', and just under one-third reported dry mouth. Dentate participants, those without xerostomia, and those reporting better oral health had better OHRQoL, reflected in lower OHIP-20 scores. Affecting 37.1% of participants, functional limitation was the most commonly experienced of the OHIP-20 domains, followed by physical disability and physical pain (18.0% and 15.6% respectively). CONCLUSIONS: The oral health of medically compromised and functionally dependent but cognitively competent older people in this study is generally poor. If transfer to long-term care is indicated, early and proper preventive measures and appropriate dental contact should be advocated in order to reduce morbidity and improve quality of life for older people.

Expression of Toll-like receptors 2 and 4 and the OPG-RANKL-RANK system in inflammatory external root resorption and external cervical resorption.

AIM: To investigate and compare the expression of the pathogen recognition receptors Toll-like receptor (TLR) 2 and TLR4, and the hard tissue resorption triad osteoprotegerin (OPG)-receptor activator of nuclear factor kappa-B ligand (RANKL)-receptor activator of nuclear factor kappa-B (RANK) in external inflammatory root resorption of endodontic origin (ER) and external cervical root resorption (ECR) by immunohistochemistry. METHODOLOGY: Formalin-fixed, paraffin-embedded archival specimens collected from teeth that were diagnosed clinically, radiographically and histopathologically with either ER (n = 9) or ECR (n = 9) were processed for immunohistochemistry to investigate and compare levels of TLR2, TLR4, OPG, RANKL, RANK, CD3, CD19 and CD83 expression. The histological features were evaluated via haematoxylin and eosin stain. Taylor's modification of the Brown and Brenn Gram stain was used for examining the presence and distribution of bacteria. All stained slides were digitally photographed and qualitatively analysed, and F test and unpaired Student's t-test were used for statistical analysis. RESULTS: Both ER and ECR showed similar immuno-histopathology characteristics of a fibrovascular connective tissue with varying degrees of inflammatory infiltrate consisting of T and B lymphocytes, dendritic cells, polymorphonuclear lymphocytes and plasma cells. Colonies of bacteria were identified in the majority of lesions, and this correlated with the cellular expression of TLR2 and TLR4 in all lesions. Similarly, all lesions showed a significantly higher (P < 0.05) level of cells expressing RANKL than OPG, indicating hard tissue resorption processes where active in the lesions. CONCLUSION: The immunohistopathology patterns of ECR samples were consistent with the bacteria-driven ER specimens, suggesting bacteria-induced inflammation may be involved in ECR.

A Micro CT study of the mesiobuccal root canal morphology of the maxillary first molar tooth.

AIM: To observe the morphology of the root canal system of the maxillary first molar mesiobuccal root using micro computed tomography and compare it to current canal classifications. METHODOLOGY: Twenty mesiobuccal roots were resected from randomly selected extracted human maxillary first molar teeth and prepared for scanning using a SkyScan micro CT scanner (SkyScan 1172 X-ray microtomograph, Antwerp, Belgium) at a slice thickness of 11.6µm. Three-dimensional images were produced and analysed to record the number and configuration of the canals, the presence of accessory canals, connections between the canals and number of canal orifices and foramina. RESULTS: The majority of roots had complex root canal systems with a second mesiobuccal canal present in 90% of the roots examined. Intercanal communications were observed in 55% of the roots. A single apical foramen was found in 15% of roots, two foramina were present in 20% and three or more foramina were present in 65%. In half of the roots, there were two orifices at the furcation level; 40% had one orifice and 10% had three orifices. Accessory canals were present in 85% of the roots. Only 60% of root canals could be classified using the classification of Weine et al. (1969) and 70% using the classification of Vertucci (1984). CONCLUSION: Micro computed tomography offers an ability to examine root canal anatomy in fine detail and confirms that the morphology of the mesiobuccal root of the maxillary first molar teeth is complex and that present morphology classifications do not fully reflect the complexity.

Antigen recognition and presentation in periapical tissues: a role for TLR expressing cells?

Bacteria are the prime cause of periapical diseases and root canal microbiology is a well-researched area of endodontics. Antigen-presenting cells (APCs) are present in periapical lesions of endodontic origin and play a substantial role in recognizing, processing and presenting pathogenic antigens to the adaptive immune system such as an effective and long-lasting immune response is generated against the specific pathogens. Toll-like receptors (TLRs) are germ-line encoded pathogen recognition receptors (PRR) expressed by various APCs which induce their maturation, lead to gene transcription in the nucleus and the production of several pro- and anti-inflammatory cytokines. Thirteen TLRs have been discovered, 10 of which have been identified in humans so far. Preliminary studies of dental pulp tissue have demonstrated various cell types expressing different TLRs in response to commonly encountered microorganisms. However, there is little information available regarding the expression and function of the various TLRs in human periapical lesions. This review discusses the interactions of various APCs in periapical lesions and the possible roles of different TLRs and APCs in pulp/periapical pathogen recognition and presentation to the adaptive immune system in the initiation and sustaining of periapical diseases.

Toll-like receptor 2 expression in refractory periapical lesions.

AIM: To investigate the expression of TLR2 in refractory periapical lesions. METHODOLOGY: Refractory periapical lesion biopsies were histopathologically and clinically categorized into asymptomatic periapical granuloma (n=10), symptomatic periapical granuloma (n=10) or periapical cyst (n=10) and prepared for immunohistochemical staining using antibodies to TLR2, CD3 and CD19 or staining with methyl green pyronin. Sections were viewed under light microscopy and the presence or absence of the target cells was correlated with the histopathological and clinical data. Additionally, TLR2 expression was quantified by counting TLR(+) cells. RESULTS: Various mononuclear inflammatory cells in the bacteria-induced periapical lesions were reactive to TLR2 antibody, with many showing morphological similarities to lymphocytes and plasma cells. Lymphocytes were the most numerous cells in the inflammatory infiltrate. In refractory periapical granuloma, CD3(+) T cells were more numerous, whereas in periapical cysts, CD19(+) B cells were more numerous. There was a statistically significant (P<0.05) higher expression of TLR2 in symptomatic periapical granuloma than asymptomatic periapical granuloma or periapical cyst. CONCLUSION: The presence of TLR-expressing cells in periapical granulomas and cysts provides further evidence that periapical cysts are likely to be sustained by the immune system via reaction to bacterial antigens.

Radiolucent inflammatory jaw lesions: a twenty-year analysis.

AIM: To determine the range and demographic and clinical features of radiolucent inflammatory jaw lesions. METHODOLOGY: Histopathology reports were reviewed to identify radiolucent jaw lesions. There were no clinical exclusive criteria, and the samples represented a wide range of clinical presentation and treatment history from multiple providers. Data were analysed using SPSS. To evaluate concordance of clinical and histological diagnoses, the clinician's provisional diagnosis was compared with the final histopathological diagnosis. RESULTS: A total of 17 038 specimens were reviewed; of these, 4983 (29.2%) were radiolucent jaw lesions, of which inflammatory lesions accounted for 72.8% (n = 3626). Periapical granulomas (59.7%) were the largest group followed by radicular cysts (29.2%). The mean age was 44 years (range 2-100 years), men and women were equally represented and the anterior maxilla was the most common site for the biopsied lesions. A provisional diagnosis was correct for only 48.3% of periapical granulomas and 36% of radicular cysts. CONCLUSIONS: This study included all presentations of periapical radiolucent lesions and showed that the incidence of cystic change in periapical lesions of endodontic origin is high at approximately 30% of all inflammatory lesions. Notwithstanding the relative frequencies, demographics and location of radiolucent inflammatory lesions presenting in the New Zealand population are comparable to that of other populations. No inflammatory radiolucent lesion can be reliably accurately diagnosed from clinical presentation and/or radiographic appearance alone.

Maxillofacial trauma and the GDP--specialty recognition and patterns of referral.

OBJECTIVE: To investigate New Zealand GDPs' awareness of maxillofacial trauma and to identify their associated referral patterns. DESIGN: Cross-sectional survey of a random sample of GDPs. METHOD: A nationwide postal questionnaire survey was sent to GDPs on the New Zealand Dental Register, maintained by the Dental Council of New Zealand. The questionnaire requested socio-demographic details, together with information on the availability of specialist services and their need for continuing professional development in oral and maxillofacial surgery (OMS). The questionnaire also asked the GDPs to indicate which specialty (plastic surgery, ear nose and throat (ENT) surgery, OMS and Other) they expected to manage--and to which specialty they would refer-seven types of maxillofacial injury. RESULTS: Some 377 GDPs responded (76.6%). The majority of GDPs expected OMS to manage maxillofacial trauma, except for facial lacerations and isolated nasal fractures which were expected to be managed by plastic surgery (83.0%) and ENT surgery (79.7%), respectively. Most GDPs (48.0% to 87.9%) referred maxillofacial trauma to OMS, except for isolated nasal fractures, for which there were similar proportions referred to ENT surgery and OMS (45.8% and 41.4%, respectively). Differences in awareness of and referral patterns for maxillofacial trauma were identified by dentist characteristics. Most GDPs (96.0%) felt there was a need for continuing professional development in OMS, and most (84.1%) preferred this to be in the form of lectures and seminars. CONCLUSION: The first-ever study of GDP referral patterns for maxillofacial trauma in New Zealand has revealed that most GDPs in New Zealand referred maxillofacial trauma appropriately to OMS.

Histopathological profile of surgically removed persistent periapical radiolucent lesions of endodontic origin.

AIM: To determine the types of periapical lesions associated with root filled teeth with persistent periapical pathosis that required surgical treatment based on specific inclusion and exclusion criteria. METHODOLOGY: Periapical lesions from a consecutive clinical sample of 100 patients were examined histopathologically to determine a definitive diagnosis. RESULTS: Females were more represented (n = 56), the average age was 46.5 years and there were no age differences between gender or lesion type. A diagnosis of periapical granuloma was the most common finding with a similar number present in females (n = 40) and males (n = 37). A cyst was present in 18% of the cases with a majority of females (n = 12) represented in the sample. Evidence of foreign material, with an appearance consistent with endodontic sealer materials, was seen in 25 periapical granulomas, two cysts and one scar. Two periapical scars were seen, one had a history of apicectomy and amalgam root-end filling while the other was associated with extruded root filling material. CONCLUSIONS: By using defined clinical inclusion and exclusion criteria a predictable clinical diagnosis of a persistent periapical lesion due to endodontic origin can be reliably made. Periapical granulomas and cysts were the most common periapical lesions of endodontic origin associated with persistent periapical pathosis with the overall incidence of periapical cysts similar to previous studies. The presence of endodontic material in a high proportion of periapical lesions suggests a cause-effect association with the inference that clinicians should employ canal preparation techniques that limit apical extrusion of material.

Dental stem cells and their potential role in apexogenesis and apexification.

Injury to an immature permanent tooth may result in cessation of dentine deposition and root maturation leaving an open root apex and thin dentinal walls that are prone to fracture. Endodontic treatment is often complicated and protracted with an uncertain prognosis frequently resulting in premature tooth loss. Postnatal stem cells, which are capable of self-renewal, proliferation and differentiation into multiple specialized cell lineages have been isolated and identified within the dental pulp, apical papilla and periodontal ligament. The ability of these cells to produce pulp-dentine and cementum-periodontal ligament complexes in vivo suggest potential applications involving stem cells, growth factors and scaffolds for apexification or apexogenesis. Similar protein expression amongst dental stem cells possibly implicates a common origin; however, the dominant cells to repopulate an open apex will be directed by local environmental cues. A greater understanding of the structure and function of cells within their environment is necessary to regulate and facilitate cellular differentiation along a certain developmental path with subsequent tissue regeneration. This review focuses on development of the apical tissues, dental stem cells and their possible involvement clinically in closing the open root apex. MEDLINE and EMBASE computer databases were searched up to January 2009. Abstracts of all potentially relevant articles were scanned and their contents identified before retrieval of full articles. A manual search of article reference lists as well as a forward search on selected authors of these articles was undertaken. It appears that dental stem cells have the potential for continued cell division and regeneration to replace dental tissues lost through trauma or disease. Clinical applications using these cells for apexogenesis and apexification will be dependent on a greater understanding of the environment at the immature root end and what stimulates dental stem cells to begin dividing and then express a certain phenotype.

cAMP included during cell suspension preparation improves survival of dopaminergic neurons in vitro.

The physical process of cell suspension preparation from embryonic ventral mesencephala (VM) may be responsible for the low numbers of dopaminergic (DA) neurons that survive following neural transplantation or in vitro culture. In particular, the disruption of cell to extracellular matrix attachment may result in cell death through deactivation of a cAMP-dependent protein kinase involved in cell survival signalling. In an attempt to reduce this death, dibutyryl cAMP was included in all solutions from explant collection to final dissociation. Pretreatment with 700 microM dibutyryl cAMP resulted in 90% survival of the DA neurons originally plated, compared with only 40% in the untreated cultures, after 5 days in vitro. Treatment of VM explants in this manner may result in major improvements in neural transplantation as a technique for the treatment of Parkinson's disease.

Effects of antioxidant pretreatment on the survival of embryonic dopaminergic neurons in vitro and following grafting in an animal model of Parkinson's disease.

The effect of pretreating cell suspensions of embryonic rat ventral mesencephala (VM) with antioxidant combinations on the survival of dopaminergic (DA) neurons was studied in vitro and following transplantation into the unilateral 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease. The in vitro experiments examined the effects of two thiol antioxidants, N-acetyl-L-cysteine (NAC) and reduced glutathione (GSH), and a member of the lazaroid family of 21-aminosteroids, U-83836E, singly and in combination, on survival of DA neurons derived from dissociated E14 rat VM tissue. For in vivo studies, cell suspensions were pretreated with combinations of NAC, GSH, and U-83836E prior to transplanting into 6-OHDA-lesioned rats to investigate whether DA neuron survival could be further improved. NAC, GSH, and U-83836E individually increased DA neuron survival in vitro and a combination of all three resulted in the greatest survival. In vivo, pretreatment with U-83836E alone resulted in a significantly greater reduction in amphetamine-induced rotation 6 weeks postgrafting compared with a control group receiving nontreated graft tissue. This functional effect correlated with a significant improvement in DA neuron survival 6 weeks postgrafting. The thiol combination pretreatment of NAC and GSH, and the triple combination of NAC, GSH, and U-83836E, however, failed to improve both functional recovery and DA neuron survival when compared with the nontreated control grafts.

Effects of anaesthetics and lazaroid U-83836E on survival of transplanted rat dopaminergic neurones.

We investigated whether different methods of anaesthesia, used on the pregnant rat when collecting embryonic donor tissue, and a lipid peroxidation inhibitor (lazaroid U-83836E) affect the survival of grafted embryonic dopaminergic neurones in hemiparkinsonian rats. There was no difference in either functional recovery or survival of dopaminergic neurones between the different euthanasia groups: (a) isoflurane sedation followed by cervical dislocation, (b) equithesin- or (c) euthatal-anaesthesia. However, lazaroid-treatment enhanced both behavioural recovery and transplant survival.

Regional variation in root dentinal tubule infection by Streptococcus gordonii.

The purpose of this study was to investigate the pattern of bacterial invasion of dentinal tubules at different regions in human roots. Specimens were obtained from single-rooted teeth that had their root canals prepared in a standard manner. Roots were then sectioned longitudinally through the canals and the resulting specimens chemically treated to remove the smear layers. Specimens were immersed in a suspension of Streptococcus gordonii for 3 weeks and then prepared for histological analysis. Sections from the cervical, midroot, and apical areas were examined. The pattern of bacterial infection of the cervical and midroot areas was similar, characterized as a heavy infection with bacteria penetrating as deep as 200 microns. Invasion of the apical dentin was significantly different, with a mild infection and maximum penetration of 60 microns.

Retention of posts with resin, glass ionomer and hybrid cements.

OBJECTIVES: To measure and compare the retention of serrated root canal posts cemented with glass ionomer, resin and resin-modified glass ionomer (hybrid) cements. METHODS: Fifty single-rooted human teeth were decoronated, treated endodontically and then embedded in resin blocks. Standard post-holes, 10 mm long, were prepared to receive 1.5 mm serrated stainless steel posts. Five equal-sized groups of roots had posts cemented using either a glass ionomer cement, one of two resin cements or one of two resin-modified glass ionomer luting cements. The cements were prepared and used according to the manufacturers' instructions. The tensile force required to dislodge the cemented posts in a testing machine was recorded. Statistical analysis was performed using Student's t-test and Mann-Whitney U-tests at the 99.9% confidence level. RESULTS: Statistical analysis revealed that posts cemented with resin A were significantly better retained (340.06 N+/-23.13 N) than those cemented with resin B (212.56 N+/-67.62 N), or either of the two resin-modified glass ionomer cements (53.90 N+/-28.42 N, 25.97 N+/-14.70 N), but not statistically better than posts cemented with the glass ionomer cement (286.16 N+/-38.71 N). The retention of posts cemented with either resin B or the glass ionomer cement was significantly better than with either hybrid cement. There was no significant difference in retention between the hybrid cements. CONCLUSION: The performance of the resin-modified glass ionomer cements was significantly below that of alternative cements in this study. Possible explanations for this finding are discussed. Dentists should be cautious in adopting this new cementing regime.

Laser Doppler flowmetry: an aid in differential diagnosis of apical radiolucencies.

The case of a patient having 2 teeth with associated apical radiolucencies that responded to conventional pulp tests is presented. A decision was made to reexamine the patient at intervals rather than perform root canal treatment. During a recall visit, use of an available laser Doppler flowmeter allowed detection of blood flow within the affected teeth. A diagnosis of periapical cemental dysplasia (cementoma) was made.

Rigidity and retention of ceramic root canal posts.

Ceramic root-canal posts offer potential advantages over other types with respect to aesthetics and biocompatibility. Any post must be sufficiently rigid and retentive to withstand functional forces. Ceraposts (1.2 mm coronal diameter, ceramic, tapering, smooth posts) and Paraposts (1.25 mm, stainless-steel, parallel, serrated posts) were tested for rigidity by means of a three-point bending test. To test retention in roots, ceramic posts were cemented using one of three protocols: (1) glass-ionomer cement, (2) silane coupling agent and resin cement, or (3) sandblasted post surface, silane coupling agent, and resin cement. Stainless-steel posts were cemented with resin. The tensile force required to dislodge the posts, following four weeks of storage in water, was recorded. Data were compared using Student's t-test and Mann-Whitney U analysis. Ceraposts were significantly more rigid than Paraposts (p < 0.001). Paraposts cemented with resin were significantly more strongly retained than Ceraposts following any cementation protocol (p < 0.001). Retention of the ceramic posts was significantly greater with a silane coupling agent and resin cement than with glass-ionomer cement (p < 0.001). Sandblasting the ceramic posts produced variable results and needs further investigation before it could be recommended.

Rigidity and retention of root canal posts.

OBJECTIVE: To test the rigidity and the retention into roots of parallel root canal posts, one a spiral vented titanium post and the other a spiral serrated, hollow, stainless steel post. A serrated, stainless steel post was used as the control. MATERIALS AND METHODS: A three-point bending test was used to test rigidity. To test retention, ten posts of each type were cemented into the roots of extracted teeth with a resin cement and the tensile loads required to remove them were compared using Student's t and Mann-Whitney U tests. RESULTS: The serrated stainless steel posts were significantly more rigid than either of the other types. The titanium posts and the stainless steel hollow posts were not significantly different in rigidity. The serrated, stainless steel posts were significantly better retained than either of the other types. The titanium posts showed greater retention than the hollow posts. CONCLUSIONS: Within the limits of the study the stainless steel, serrated posts were superior to the two newer types in terms of rigidity and retention into roots.