Intact Teeth Research Articles

Retention of teeth in the fracture gaps of the mandible: a retrospective analysis.

Since the introduction of miniplate osteosynthesis and the use of prophylactic antibiotics, the complication rate related to the teeth in the fracture gap has significantly decreased. Currently, there are still no established guidelines for the management of such teeth in mandibular fracture lines. However, the long-term viability of these teeth within the fracture gap remains uncertain. Therefore, this study aimed to assess the survival rate of teeth located within the mandibular fracture line and evaluate related follow-up treatments over a minimum period of one year. This retrospective study examined 184 patients who underwent surgical treatment for mandibular fractures between January 2018 and December 2021. A total of 189 teeth located in the fracture line were analyzed. Clinical and radiological parameters were collected, including patient age and gender, fracture etiology and location, intraoperative tooth treatment, as well as complications related to both the fracture and the affected teeth in long term. Most of the examined teeth remained uneventful, with postoperative tooth-related complications seen in 14 (7.4%) teeth. The most common complications were symptomatic apical periodontitis (n = 9, 4.8%) and increased tooth mobility (n = 3, 1.5%). A correlation was found between complications and trauma-related tooth luxation (p = 0.002, OR = 15.2), as well as prior teeth connected to retainers or orthodontic appliances (p = 0.001, OR = 10.32). Tooth-related complications are rare when intact teeth are retained within the fracture gap. Therefore, unless there is a definitive intraoperative indication for extraction, it is recommended to preserve the teeth in the fracture line. Intact teeth in the fracture line of the mandible should not be primarily extracted.

Assessment of the quality of life of patients with abfraction tooth defects

BACKGROUND: The evaluation of the effectiveness of treatment of abfraction defects with respect to patients quality of life is relevant.
 AIM: To analyze the results of the treatment of abfraction defects according to quality of life.
 MATERIALS AND METHODS: A questionnaire survey of 158 people aged 3049 years was conducted. Group 1 (n=34) received the modified adhesive protocol (glutaraldehyde and an adaptive layer of flowable composite) as muscle relaxant mouthguard; group 2 (n=36), modified adhesive protocol, not used a muscle relaxant mouthguard; group 3 (n=31), basic adhesive protocol as muscle relaxant kappa; group 4 (n=27), basic adhesive protocol, did not use a muscle relaxant mouthguard; and group 5 (n=30), patients with intact teeth. The quality of life was assessed before treatment and 6 months and 1 year after tooth restoration. The Oral Health Impact Profile-14 (OHIP-14) Quality of Life Questionnaire was used.
 RESULTS: A good initial level of quality of life was found in 35.2% of patients with abfraction defects and a satisfactory one in 64.8%. The average quality-of-life score of groups 14 was 12.9 (95%, 12.413.3). Physical pain, with a score of2.73 (95%, 2.632.84), made the greatest contribution to the quality of life. Twelve months after treatment, groups 14 had a significant average decrease in OHIP-14 by 7.7%. The OHIP-14 score on the physical pain scale decreased in group 1 by 28.8%, group 2 by 25.2%, group 3 by 17.5%, and group 4 by 13.2%.
 CONCLUSIONS: The clinical manifestations of the abfraction defects of teeth significantly affect the quality of life of patients, particularly on physical pain and physical discomfort. The best dynamics of the quality of life was registered in patients who received the modified adhesive protocol and a muscle relaxant mouthguard.

Fracture Resistance of Endodontically Treated Premolars Using Nanohybrid Composite, Fiber-Reinforced Composite, Horizontal Glass Fiber Posts, and Ceramic Inlays: An In Vitro Study

IntroductionThis study evaluated the resistance to fracture of endodontically treated premolars (ETPs) with mesio-occluso-distal (MOD) cavities filled with nanohybrid composite (NHC), fiber-reinforced composite (FRC), horizontal glass fiber posts (HFP), and ceramic inlays (CI). MethodsEighty-four intact maxillary premolars were taken, and endodontic treatment was performed followed by MOD cavity preparations (except in the control group). They were distributed into 7 groups based on type of restoration: intact teeth (control group), ETP + MOD (not restored), NHC, FRC + NHC, HFP + NHC, FRC + HFP + NHC, and CI groups. Samples were subjected to universal testing machine until the fracture occurred and failure mode was visually inspected. ResultsMean and standard deviation of fracture resistance of the 7 groups ranged from 265.6 ± 68.0 N to 1023.7 ± 76.5 N. The highest reading was noted for intact teeth followed by FRC + HFP + NHC group and then the CI group, with no significant difference among the 3 groups. The lowest reading was noted for the ETP + MOD group. Maximum unrepairable fractures were seen in the ETP + MOD and CI groups. ConclusionFRC + HFP + NHC combination and CIs increased the resistance to fracture of ETPs significantly.

Evaluation of the Pulp Chamber Temperature during Tooth Veneer Preparation Using Burs with Different Degrees of Wear-A Preliminary In Vitro Study.

The heat produced during tooth preparation could be a source of damage for dental pulp, and many variables are involved in this process. The aim of this in vitro study was to evaluate whether the different degrees of wear of the diamond burs significantly influenced the temperature changes in the pulp chamber during tangential veneer preparation. The sample comprised 30 intact permanent monoradicular teeth, randomly assigned to three study groups of 10 teeth each, of which 5 had the pulp tissue preserved and 5 had thermoconductive paste in the pulp chamber. For prosthetic preparation, we used new burs in the first group, burs at their fifth use in the second group, and burs at their eighth use for the third group. The pulp chamber temperature was evaluated at the start, after one minute, and after three minutes of preparation, using a k-type thermocouple. The results of the three-way ANOVA and Tukey post hoc comparisons showed a highly significant effect of the time of measurement, while the pulp condition and the degree of wear of the burs had no effect. In conclusion, the different degrees of wear of conventional diamond burs do not produce statistically significant different changes in the pulp chamber temperature.

Fracture resistance and failure mode of endodontically treated premolars reconstructed by different preparation approaches: Cervical margin relocation and crown lengthening with complete and partial ferrule with three different post and core systems.

To assess the fracture resistance and failure mode of endodontically treated premolars reconstructed by different preparation approaches: cervical margin relocation (CMR) and crown lengthening (CL) with complete ferrule (CLF) and partial ferrule (CLPF) with three different post and core systems. In this in vitro study, 100 maxillary premolars were assigned to the following 10 groups according to their preparation approach and type of post and core system (n = 10): (I) control (intact teeth), (II) prefabricated fiber post (PFP) and composite core with CMR (PFP-CMR), (III) polyethylene fiber-reinforced composite (PEFRC) with CMR (PEFRC-CMR), (IV) casting post (CP) and core with CMR (CP-CMR), (V) PFP-CLPF, (VI) PEFRC-CLPF, (VII) CP-CLPF, (VIII) PFP-CLF, (IX) PEFRC-CLF, and (X) CP-CLF. After thermomechanical loading, the fracture resistance and failure mode were assessed. Data were analyzed statistically (α = 0.05). In all post and core systems, the CLPF approach had lower fracture resistance than CMR (p<0.05); CLF showed higher fracture resistance than CLPF only in the PFP system (p = 0.038). In PEFRC and CP systems, the difference between CLF and CLPF was not significant (p > 0.05). No significant difference was found in fracture resistance of different post and core systems with the same preparation approach (p > 0.05). CLPF showed the highest frequency of favorable, and CLF showed the highest frequency of unfavorable fractures. CLPF yielded lower fracture resistance than CMR. The difference in fracture resistance was not significant between CLF and CMR but the frequency of unfavorable fractures was higher in CLF than in other groups.

Fracture Resistance of Endodontically Treated Teeth Restored With Short Fiber Reinforced Composite and a Low Viscosity Bulk Fill Composite in Class II Mesial-Occlusal-Distal Access Cavities: An Ex-vivo Study.

Background Teeth undergoing endodontic therapy are prone to structural weakening and increased risk of fractures. The absence of marginal ridges and pericervical dentin further compromises the fracture resistance. The choice of the post-endodontic coronal seal is crucial for the effectiveness of endodontic therapy. Aim and Objectives This study compared the fracture resistance and fracture modes of endodontically treated teeth (ETT) with mesial-occlusal-distal(MOD) cavities restored with two different posterior composite resins: e-glass fiber reinforced composite (FRC) (everX Posterior) and flowable bulk fill composite (SDR Flow+). Materials and Methods Sixty human maxillary first bicuspids were divided into four groups: Group PC- positive control (intact teeth), Group NC- negative control (unrestored endodontically treated teeth), Group EXP- samples restored with everX Posterior and nano-hybrid composite, and Group SDR- samples restored with SDR Flow+ and nano-hybrid composite. The NC, EXP, and Smart Dentin Replacement (SDR) samples underwent endodontic procedures and MOD cavity preparation. The samples from EXP and SDR groups were restored with composite resins as post-endodontic coronal seals. The fracture resistance was evaluated using a Universal Testing Machine (UTM), and fracture modes were examined under a dental operating microscope (DOM) at 6x magnification. Statistical tests were performed using One-way ANOVA and Tukeys' post hoc tests. Results The mean fracture resistance of the experimental groups was as follows: PC- 880.1 ± 209.3 N; NC- 238.1 ± 15.4 N; EXP- 766.1 ± 50.2 N; SDR- 540.8 ± 49.4 N. The highest fracture resistance values were observed in the PC group, whereas the NC group showed the least. The EXP group exhibited significantly higher fracture resistance than the SDR group. Adhesive failure was observed in most samples in the EXP group, whereas samples in the SDR group showed more cohesive failures. Favorable fractures were more prevalent in samples restored with EverX posterior. Conclusion The study findings suggest that everX Posterior can enhance the fracture resistance of structurally compromised ETT. Samples restored with everX Posterior showed a favorable mode of fracture, which can be restored. Applying FRCs can contribute to the longevity and success of endodontic treatment by reinforcing the weakened tooth structure and preventing fractures.

Effect of Proximal Caries-driven Access on the Biomechanical Behavior of Endodontically Treated Maxillary Premolars

IntroductionThis study investigated the effects from the carious cavity and access from it on the fracture resistance of endodontically treated maxillary premolars using finite element analysis (FEA). MethodsA maxillary premolar was used to compare 3 types of access cavity related to having a proximal carious defect: caries-driven access (CDA), conservative access that has a mesial component (MCA), as well as traditional access with the same mesial component (MTA). Cyclic loading was simulated on the occlusal surface, and number of cycles until failure (NCF) was compared with the intact tooth model (IT). Mathematical analysis was done to evaluate the stress distribution patterns and calculated maximum von Mises (vM) and maximum principal stresses (MPS), with emphasis on pericervical region as a specific area of interest. ResultsMaximum vM registered on the IT was 6.14 MPa. CDA provided the highest NCF with 92.28% of the IT, followed by MCA (84.90%) and MTA (83.79%). The vM and MPS analysis showed that the stress values and patterns are affected more by the proximity of the occlusal load to the tooth/restoration interface. Concerning the pericervical region, maximum vM was registered for IT (4.11 MPa), followed by CDA (4.85 MPa) and then MCA (8.13 MPa) and MTA (8.61 MPa), whereas the MPS analysis revealed that CDA showed the highest magnitude of tensile stresses. ConclusionsA proximal CDA benefits the mechanical properties of maxillary premolars; however, its impact on the biological aspect should be assessed to provide a ruling for/against it.

Impact of Contracted Endodontic Access Cavities on the Fracture Resistance of Endodontically Treated Teeth After Mechanical Aging by Simulated Chewing Forces

IntroductionThis in vitro study aimed to comparatively evaluate the fracture resistance of contracted endodontic cavities (CECs) versus traditional endodontic cavities (TECs) in mandibular molars after subjecting the samples to a chewing simulator. MethodsA total of 24 freshly extracted human mandibular molars were included in the study. Teeth with intact crowns and mature root apices that were devoid of caries, attrition, restorations, and cracks were selected and randomly assigned to 3 groups (n = 8) as follows: Group 1: TECs, Group 2: CECs, and Group 3: intact teeth (control group). After endodontic treatment, the teeth were restored with EverX bulk-fill composite and layered occlusally with nanohybrid composite SolareX and subjected to a chewing simulator where 240,000 masticatory cycles were simulated, which translates to 1 year of clinical function. The teeth were then subjected to static loading in a universal testing machine and the maximum load to fracture and the pattern of failure (restorable/unrestorable) were recorded. Data were evaluated with analysis of variance and the Tukey post hoc test for multiple comparisons. ResultsThe CEC group had higher fracture resistance when compared with the TEC group; however, the difference was not statistically significant. The fracture resistance of the samples in the control group was statistically higher than those in the experimental groups (P < .005). ConclusionsThere was no difference observed in the fracture resistance of mandibular molars with TECs and CECs subjected to masticatory loading.

BRUXCHECKERS-АНАЛИЗ ПАРАФУНКЦИОНАЛЬНОЙ АКТИВНОСТИ ЖЕВАТЕЛЬНЫХ МЫШЦ У ПАЦИЕНТОВ C АБФРАКЦИОННЫМИ ДЕФЕКТАМИ ЗУБОВ

In order to improve the quality of diagnostics of the state of the dental system of patients with abfractive defects of teeth, the features of the dental status of 128 patients aged 30-49 years were studied. The study of dental status included generally accepted methods (complaints, anamnesis, examination) and functional analysis of occlusive-articulatory relationships of dentition with the use of BruxChecker diagnostic mouthguards. A high frequency of complaints of hypersensitivity of teeth has been established. Significant symptoms were functional overload, enamel cracks, pathological tooth abrasion. The periodontal condition of teeth with abfractive defects was characterized by a roller-like gum recession without inflammation of the gingival margin and periodontal pockets. Comparative Bruxcheckers analysis by Fisher's exact criterion of the parafunctional activity of the masticatory muscles revealed significantly significant differences F=21.702 (p &lt;0.001) between the examined with abfractive defects of teeth (average class 5.06±0.4) and intact teeth (average class 1.81±0.2). BruxChecker-analysis of the topography of occlusal contacts of teeth during nocturnal movements of the lower jaw confirmed the assumption of the presence of parafunctional activity of the masticatory muscles in patients with abfractive defects of teeth. The highest percentage of observations occurred in the fifth (28.9%, 95% CI:21.1-36.8) and sixth (42.2%, 95% CI: 33.6 – 50.7) classes. This indicated that the chewing system was in the stage of decompensation. The obtained data substantiate the inclusion in the algorithms of treatment of patients with abfractive defects of methods for eliminating sensitivity and restoring the anatomical shape of teeth with preliminary correction of the parafunctional activity of the dental system.

К ПРОБЛЕМЕ ДИАГНОСТИКИ В ПРЕВЕНТИВНОЙ ЭНДОДОНТИИ

Subject. The most significant problem of modern preventive endodontics is to determine the vitality of the pulp and, accordingly, to make a decision about the choice of treatment method. The early stages of inflammation in the pulp may not be fully detected clinically and require the inclusion of additional examination methods that assess the state of microcirculation in the neurovascular bundle, as well as the severity of the immune response. These methods include: clinical and immunological examination of the gingival fluid (GF), as well as the assessment of tissue perfusion using laser Doppler flowmetry (LDF). &#x0D; Objectives. The purpose of the study is to optimize the diagnostics of the dental pulp condition in the context of implementing the concept of preventive endodontics.&#x0D; Methodology. 37 patients aged 19–29 years with a diagnosis of K 04.00 "Pulp hyperemia" were examined. In addition to the basic methods of examination, LDF and immunological study of GF (IL-1β, TNF-α, IL-4) were used. In each patient, 1 tooth with pulp hyperemia and 1 intact (control) tooth were examined.&#x0D; Results. In the immunological analysis of DF in the area of teeth with pulp hyperemia, higher values of cytokines were obtained compared to intact teeth (p &lt; 0.05). At the same time, in the area of 2 teeth with pulp hyperemia (5.4%), the level of cytokines was higher than their average values in the group of carious teeth. LDF of teeth with pulpal hyperemia also revealed higher values of M and σ compared with similar parameters in control teeth (p &lt; 0.05). At the same time, in 2 cases, the highest levels of LDF were noted, which was consistent with the previously observed high values of cytokines in the gingival fluid in these loci. Moreover, after 2 weeks, a clinic of irreversible pulpitis was observed in these 2 teeth.&#x0D; Conclusion. When diagnosing reversible forms of pulpitis and deciding on the possibility of biological treatment of pulp hyperemia, it is necessary to assess the state of microcirculatory changes that have occurred in the pulp tissue, as well as the level of local immunological reactions.

THE STATE OF BONE METABOLISM IN PATIENTS WITH GENERALIZED PERIODONTITIS IN DIABETIC OSTEOPATHY

Diagnosis of the state of bone metabolism in patients with generalized periodontitis burdened with type 2 diabetes is an important step in the complex of treatment and prevention measures for this pathology. The purpose of the study was to create evidence-diagnostic criteria for assessing and predicting the severity of the course of generalized periodontitis in diabetic osteopathy based on the study of the variability of bone remodeling. Research material and methods. In order to select homogeneous groups, a clinical and radiological examination of 166 patients with generalized periodontitis, associated and not associated with type 2 diabetes, was conducted. The age of the patients was in the range of 30-50 years (on average 42.5+- 2.34 years). Among them there were 99 (59.6 %) women and 67 (40.4 %) men. The degree of severity of generalized periodontitis was verified according to generally accepted clinical and radiological criteria outlined in modern and domestic classifications: 76 (45.8 %) patients had chronic generalized periodontitis and 90 (54.2 %) had chronic rapidly progressive periodontitis. The control group consisted of 19 almost healthy voluntary donors of similar age (on average 41.5+-2.7 years) and sex without endocrine pathology, with healthy periodontium and intact teeth. Research results and their discussion. Evaluation of the Hounsfield index and markers of bone metabolism in different groups of patients with generalized periodontitis in type 2 diabetes with average statistical analysis showed that they are directly correlated with the severity and the course of generalized periodontitis, the stage of compensation, the severity and duration of diabetes. Conclusions. The peculiarity of the clinical course of generalized periodontitis in type 2 diabetes mellitus, burdened by diabetic osteoporosis, is caused and manifested by a decrease in the bone structures of the periodontium in the processes of osteosynthesis and an increase in the intensity of bone resorption. A feature of the manifestation of rapidly progressive and chronic generalized periodontitis in diabetic osteopathy and without systemic pathology is the increase, independent of the clinical picture of the disease, of signs of osteoporosis activation and a decrease in osteosynthesis. To verify the activity of osteosynthesis and bone resorption in periodontal tissues, the following have predictive value: diagnosis of different directionality and intensity of bone remodeling based on the levels of quantitative content in blood serum of the levels of markers of bone metabolism.

Influence of voxel size and filter type on detecting vertical root fracture using cone-beam computed tomography.

Vertical root fractures (VRFs) can start at any level of the root and progress longitudinally to the coronal attachment. This study aimed to investigate the effects of different exposure parameters used when obtaining CBCT scans in detecting simulated VRFs. Hence, 80 intact human mandibular single-rooted pre-molar teeth without root fractures were included in the study. No statistically significant difference was found between the filters in terms of VRF detection in the group with the roots with only root canal filling (Groups 1 and 5); however, 100 voxels were found to be more successful in terms of VRF detection than other voxel sizes. Results of this study suggest that using lower voxel sizes leads to an accurate diagnosis of vertical root fracture, in addition, our results revealed that using AR filters did not improve the diagnostic accuracy in detecting VRFs.

Clinical survival of No-prep indirect composite laminate veneers: a 7-year prospective case series study

BackgroundThe no preparation technique which is a reversible form of treatment characterized by the absence of tooth tissue preparation and preserves the soft tissue architecture while preserving all natural tooth structures is indicated in cases where the tooth structure allows material to be added. The aim of this study is to evaluate the clinical performance and survival rates of indirect composite laminate veneers with no preparation after 7 years.Materials and methodsA total of 80 indirect composite veneers were placed on maxillary anterior teeth in 35 patients (n = 80). Diastema (n = 64), wedge tooth anomalies (n = 9) and re-shaping (n = 7) were the main indications for veneer treatments. All laminate veneers were fabricated with an indirect microhybrid composite material (Gradia, GC Dental). No tooth preparation was performed. Light-cured resin cement (Choice 2, Bisco) was used to lute the veneers. Composite veneers were evaluated using Modified United States Public Health Service criteria. Survival rates of the veneers were calculated using Kaplan-Meier statistics. The data containing the results of the USPHS criteria at baseline, 2 years and 7 years was statistically analyzed using Wilcoxon Signed Rank test at the 0.05 level of significance.ResultsThe overall survival rate was 91.3%. After 7 years, 7 absolute failures including 4 debonding (marginal adaptation, score 4) and 3 fractures (fracture of restoration, score 3) were noted. Color match was scored as 1 (n = 34) and 2 (n = 15). Slightly rough surfaces (41 of 73 laminates) and slight marginal discoloration (15 of 73 laminates) were noted. The overall scores after 84 months were significantly higher than the baseline scores for the marginal adaptation (p = 0.008), color match (p = 0.000), marginal discoloration (p = 0.000), surface roughness (p = 0.000), and fracture of restoration (p = 0.001) criteria.ConclusionsIn this study, indirect composite veneers without any preparation on maxillary anterior teeth showed acceptable performance in terms of both survival rate and quality of restorations. This procedure offers a predictable and successful treatment that ensures maximum preservation of the intact tooth.

Stronger than Ever: Multifilament Fiberglass Posts Boost Maxillary Premolar Fracture Resistance.

This paper investigates the influence of cavity configuration and post-endodontic restoration on the fracture resistance, failure mode and stress distribution of premolars by using a method of fracture failure test and finite elements analysis (FEA) coupled to Weibull analysis (WA). One hundred premolars were divided into one control group (Gcontr) (n = 10) and three experimental groups, according to the post-endodontic restoration (n = 30), G1, restored using composite, G2, restored using single fiber post and G3, restored using multifilament fiberglass posts (m-FGP) without post-space preparation. Each experimental group was divided into three subgroups according to the type of coronal cavity configuration (n = 10): G1O, G2O, and G3O with occlusal (O) cavity configuration; G1MO, G2MO, and G3MO with mesio-occlusal (MO); and G1MOD, G2MOD, and G3MOD with mesio-occluso-distal (MOD). After thermomechanical aging, all the specimens were tested under compression load, and failure mode was determined. FEA and WA supplemented destructive tests. Data were statistically analyzed. Irrespective of residual tooth substance, G1 and G2 exhibited lower fracture resistance than Gcontr (p < 0.05), whereas G3 showed no difference compared to Gcontr (p > 0.05). Regarding the type of restoration, no difference was highlighted between G1O and G2O, G1MO and G2MO, or G1MOD and G2MOD (p > 0.05), whereas G3O, G3MO, and G3MOD exhibit higher fracture resistance (p < 0.05) than G1O and G2O, G1MO and G2MO, and G1MOD and G2MOD, respectively. Regarding cavity configuration: in G1 and G2, G1O and G2O exhibited higher fracture resistance than G1MOD and G2MOD, respectively (p < 0.05). In G3, there was no difference among G3O, G3MO and G3MOD (p > 0.05). No difference was found among the different groups and subgroups regarding the failure mode. After aging, premolars restored with multifilament fiberglass posts demonstrated fracture resistance values comparable to those of an intact tooth, irrespective of the different type of cavity configuration.

Biomechanical Performance of Mandibular Molars with Deep Mesio-Occlusal-Distal Cavities Rehabilitated with Horizontal Posts: A 3D Finite Element Analysis.

To compare and contrast by three-dimensional finite element analysis the biomechanical performance of deep mesio-occlusal-distal cavities of mandibular molars reinforced by different sizes of horizontal fiber posts. The finite element (FE) stress analysis was performed with the ANSYS, a commercial finite element method package. Based on the evidence-based scientific data and on the mechanical properties of materials, i.e., Young's modulus and Poisson ratio, the model of a mandible and mandibular first molar was replicated. The mandibular molar models replicating the clinical scenarios were simulated, designed, and built, assuming all materials to be homogenous, isotropic, and linearly elastic as follows: Model 1 control: the model of an intact first mandibular molar. Model 2: the prepared cavity mesio-occlusal-distal is replicated by the subtraction Boolean method. The remaining thickness of dentin is 1 mm. Model 3: these were rehabilitated by three different diameters of two horizontal fiber posts. Model 3A: fiber post diameter 1 mm, Model 3B: 1.5 mm and Model 3C: 2 mm. The dimensions of the cavity, the intercuspal distance between buccal walls and lingual walls, and the distance of placement of the post from occlusal reference points were all kept constant for all three subgroups of Model 3. The cavities of Model 3 were restored with Filtek bulk-fill posterior composite. After meshing the models, loads were defined on the buccal and lingual distal cusps with a constant value of 600 N and at an angle of 45°. The results of finite element analysis are expressed as stresses, i.e., tensile compressive, shear, or a combination known as von Mises stresses. The overall von Mises stresses were as follows: Model 1:154.83 Mpa; Model 2: 376.877 Mpa; Model 3A: 160.221 Mpa; Model 3B: 159.488 Mpa; Model 3C: 147.231 Mpa. Statistical analysis of the compiled data was carried out. It was seen that there was a significant difference in stress values from the intact tooth Model 1 and cavity Model 2 (p < 0.05) with means values of 53.1 and 139.22, respectively. The means of all subgroups were comparable but there was a statistically significant difference between Model 3, i.e., 3A (67.74), Model 3B (60.47), Model 3C (53.70), and Model 2. Model 1 and Model 3C had comparable mean values. Rehabilitation of deep mesio-occlusal-distal cavities of molars with intact buccal and lingual walls with the aid of a horizontal post of any diameter has a similar stress distribution to an intact tooth. However, the biomechanical performance of a 2 mm horizontal post was exacting of the natural tooth. Horizontal posts can be included in expanding our restorative option for rehabilitating grossly mutilated teeth.

Bond strength of various post-core restorations with different lengths and diameters following cycle loading

PurposeThis in vitro study aims to evaluate the bonding strengths of Polyether ether ketone (PEEK), Polyether ketone (PEKK), Fiber, and Zirconia (ZrO2) post-core restorations with posts in different diameter and length following chewing simulator. Materials and methodsEndodontic treatment was performed on 256 intact maxillary central teeth. The test specimens were prepared in four groups according to the types of materials: Glass fiber post-composite core (FB-n:64), Zirconia post-core (Zr-n:64), PEEK post-core (PE-n:64), and PEKK post-core (PK-n:64). The groups were divided into four subgroups according to diameter and length (n:16): Group 1: 10 mm length 1.75 mm diameter, Group 2: 10 mm length 1.5 mm diameter, Group 3: 7 mm length 1.75 mm diameter, Group 4: 7 mm length 1.5 mm diameter. Custom PEKK, PEEK, Zirconia post-cores, and Zirconia crowns were milled on the CAD/CAM. The post-cores and crowns were cemented to the teeth with dual-cure resin cement. After that, all subgroups were divided into control and cyclic loading groups. During the cycling, the control test group was kept in distilled water at 37±1oC before the push-out test. Half of the specimens were loaded with 250,000 cycles and 50 N with a chewing simulator. All test specimens had 1.5 mm sections taken from their roots. Then, the push-out test was applied to these sections for bond strength. Data were analyzed by Mann-Whitney U test, Shapiro-Wilk, Kruskal-Wallis's test, and Chi-Square. The statistical significance level was determined as 0.05. ResultsThe bond strength of all test groups decreased after the cycling loading. The bond strength values of zirconia posts showed a statistically significant difference (p < 0.05). The 10 mm length 1.75 mm diameter posts made of Zirconium had the highest bond strength observed in all control and cyclic loading groups of test specimens (9.74 MPa-6.25 MPa). The PEEK test specimens with a 7 mm length and 1.75 mm diameter showed the weakest bond strength in all control and cyclic loading groups (5.44 MPa-3.37 MPa). The average of the cervical region's bond strength values was statistically significantly higher than the apical region (p < 0.05). ConclusionWithin the limitations of this study, one-piece custom-milled Zirconia post-cores appear promising, as they perform well under functional forces, especially in the anterior region. In addition, custom-milled PEKK post-cores might be considered a suitable alternative to prefabricated fiber-reinforced posts.

Effect of short fiber-reinforced composite combined with polyethylene fibers on fracture resistance of endodontically treated premolars

Statement of problemWhether direct coronal restorations of endodontically treated teeth with short fiber-reinforced composite combined with polyethylene fibers provide adequate mechanical strength is unclear. PurposeThe purpose of this in vitro study was to compare the fracture strength of endodontically treated premolars with standardized mesio-occluso-distal (MOD) preparations restored with short fiber-reinforced composite (SFRC) combined with polyethylene Ribbond fibers (PRFs). Material and methodsA total of 40 premolars were selected and distributed into 4 groups (n=10) as follows: group restored with SFRC (EverX Posterior), group restored with PRF (Ribbond fibers), and group restored with the combination PRF+SFRC, all followed by a conventional composite resin (IPS Empress Direct). MOD preparations and endodontic treatments were prepared except in the control group (intact teeth). MOD preparations and endodontic treatments were prepared except in the control group (intact teeth). Specimens were loaded using a universal testing machine until fracture occurred at a crosshead speed of 0.5 mm/min, and the failure type and fracture patterns was reported descriptively. The mean values of the groups were analyzed by using the Shapiro-Wilk test and 1-way ANOVA tests (α=.05). ResultsRestoration with PRF+SFRC provided the highest mean ±standard deviation fracture resistance (288.2 ±73.5 N). Restoration with just PRF had the lowest values (192.4 ±25.4 N), which were statistically different from those of SFRC and PRF+SFRC (P<.05). The predominant mode of failure was mixed, and all fracture patterns were favorable. ConclusionsReinforcing endodontically treated premolars with MOD cavities with Ribbond fibers followed by a conventional composite resin enhanced fracture resistance and may be suitable for the direct coronal restoration of large posterior cavities in stress-bearing areas.

Enamel chipping and its ecological correlates in African papionins: Implications for hominin feeding behavior.

African papionins are classic paleoecological referents for fossil hominins. Enamel chips on the teeth of baboons and hominins are argued to represent responses to similar dietary habits; however, a comprehensive analysis of modern papionin chipping is lacking, leaving open the question of analog suitability. Here, we investigate patterns of antemortem enamel chipping across a diverse set of African papionin species occupying a range of ecological niches. We compare papionin chipping frequencies to estimates for Plio-Pleistocene hominins to address hypotheses of habitat and/or dietary similarities. Antemortem chips in seven African papionin species were scored on intact postcanine teeth (P3-M3) using established protocols. Chip size was scored on a tripartite scale. Papio hamadryas and Papio ursinus-two common paleoecological referents-display higher levels of chipping than Plio-Pleistocene hominin taxa (Australopithecus and Paranthropus) posited to have similar dietary habits. Papio populations occupying dry or highly seasonal habitats accumulate more large chips than Papio taxa occupying more mesic habitats, and terrestrial papionins chip their teeth more often than closely related taxa occupying arboreal niches. Chipping is present on the teeth of all Plio-Pleistocene hominins; however, chipping in baboons (P.ursinus and P.hamadryas) consistently exceeds most hominin taxa. Chipping frequencies on their own do not reliably sort taxa into major dietary groupings. We conclude that the large differences in chipping frequency may instead reflect habitat use and food processing idiosyncrasies. Less chipping in Plio-Pleistocene hominin teeth compared to modern Papio is more likely attributable to differences in dental morphology rather than diet.

The Indicators of Molar Coefficients of the Chemical Elements in Dentin and their Correlation with Enamel

Objectives:Determination of molar coefficients of the chemical elements in dentin, their possible correlation with tooth enamel. Material and Methods:There were examined 29 clinically extracted teeth of both jaws and their longitudinal sections (12 clinically intact teeth, 10 teeth with wedge-shaped defects, 7 teeth with cervical caries) of the patients aged 25to 54 with the help of JSM-6490 LV focused beam electron microscope (scanning) with system of energy-dispersive X-ray microanalysis. We have determined the chemical composition of 290 enamel areas and 235 dentine areas in the incisal region (tubercle), equator, cervical area as a percentage of the weight amounts of carbon, oxygen, calcium, phosphorus, sodium, magnesium, sulfur, chlorine, zinc, potassium, aluminum, we have identified their molar coefficients. Results: The chemical composition of dentin differed in the values of Na/Mg, Al/Zn, Mg/Ca, K/Na (p≤0.05) in all studied topographical regions of the samples. Higher values of Na/Mg and lower values of Al/Zn were identified in the teeth with cervical caries (p≤0.05). Correlation was found in dentin: inverse between Ca/P and P/Ca, Mg/Ca and Na/Mg, Ca/Mg and Mg/Ca, Mg/P and Na/Mg, Mg/P and Ca/Mg, direct between Ca/Mg and Na/Mg, Mg/P and Mg/Ca (p≤0.05). High correlation was determined between molar coefficients in enamel and dentin: Mg/Ca and Mg/P (direct), Ca/P and P/Ca (inverse), p&amp;lt;0.0001. Conclusions:The differences in the indicators of molar coefficients in dentin, their correlation with enamel are probably associated with the peculiarities of the pathological processes in the cervical region and it requires further study.

Fracture Load of Mesio–Occluso–Distal Composite Restorations Performed with Different Reinforcement Techniques: An In Vitro Study

Mesio-occluso-distal (MOD) cavity preparations are often fragile due to the amount of tooth and carious structure removed. MOD cavities can often fracture if left unsupported. The study investigated the maximum fracture load of mesi-occluso-distal cavities restored using direct composite resin restorations with various reinforcement techniques. Seventy-two freshly extracted, intact human posterior teeth were disinfected, checked, and prepared according to predetermined standards for mesio-occluso-distal cavity design (MOD). The teeth were assigned randomly into six groups. The first group was the control group restored conventionally with a nanohybrid composite resin (Group I). The other five groups were restored with a nanohybrid composite resin reinforced with different techniques: the ACTIVA BioACTIVE-Restorative and -Liner as a dentin substitute and layered with a nanohybrid composite (Group II); the everX Posterior composite resin layered with a nanohybrid composite (Group III); polyethylene fibers called "Ribbond" placed on both axial walls and the floor of the cavity, and layered with a nanohybrid composite (Group IV); polyethylene fibers placed on both axial walls and the floor of the cavity, and layered with the ACTIVA BioACTIVE-Restorative and -Liner as a dentin substitute and nanohybrid composite (Group V); and polyethylene fibers placed on both axial walls and the floor of the cavity and layered with the everX posterior composite resin and nanohybrid composite (Group VI). All teeth were subjected to thermocycling to simulate the oral environment. The maximum load was measured using a universal testing machine. The highest maximum load was exhibited by Group III with the everX posterior composite resin, followed by Group IV, Group VI, Group I, Group II, and Group V. A statistically significant difference was demonstrated between groups (p = 0.0023). When adjusting for multiple comparisons, there were statistical differences specific to comparisons between Group III versus I, Group III versus II, Group IV versus II, and Group V versus III. Within the limitations of the current study, it can be concluded that a higher maximum load resistance can be achieved (statistically significant) when reinforcing nanohybrid composite resin MOD restorations with everX Posterior.