Surfaces Of Third Molars Research Articles

Influence of Er:YAG laser irradiation settings on dentin-adhesive interfacial ultramorphology and dentin bond strength.

This study evaluated the effects of Erbium-doped yttrium aluminium garnet (Er:YAG) laser settings and dentin bonding agents on ultramorphological characteristics of resin-laser-irradiated dentin interfaces and dentin bond strength (BS) of these adhesive systems. Additionally, dentin depth affected by Er:YAG laser irradiations was measured. The experiments were performed on occlusal dentin surfaces of third molars that were flattened with 600-grit SiC sandpaper. Treated-dentin with laser settings (250 mJ/4 Hz and 160 mJ/10Hz) were the experimental groups, while SiC abraded dentin was the control. These three dentin treatments and three adhesives (two self-etchings and one etch-&-rinse adhesive) formed nine groups for the ultramorphology of laser-ablated dentin-adhesives interfacial analysis, using a transmission electron microscope (TEM). For BS (n=8), the same nine groups were tested with addition of the two evaluation times (24 h after sample preparation or 1 year). The depths of Er:YAG laser effects into the dentin were measured using a TEM (n=10). Ablated-dentin depth and BS data were analyzed by one- and three-way ANOVA, respectively, and Tukey's test (α=0.05). Hybrid layer formation was only observed for controls, while for laser-treated dentin, adhesives were bonded to dentin with resin tags formation. Laser settings reduced the BS for all adhesives at 24 h, while at 1 year, etch-&-rinse adhesive presented the highest BS, regardless treatment (control or laser settings). Dentin depth affected by laser settings was similar. The laser irradiation altered the bonding mechanism of the adhesives to dentin and reduced the BS for self-etching adhesives. Etch-&-rinse adhesive yielded the highest BS at 1 year. Laser settings similarly affected the dentin in depth. HIGHLIGHTS: Er:YAG laser irradiation settings produced similar effects on depth and bond strength to dentin. The etch-&-rinse adhesive yielded the highest dentin bond strength regardless of the type of dentin treatment at 1 year.

The Anatomical Position and Size of Greater Palatine Foramen and Canal in an Iranian Sample Using Cone Beam Computed Tomography.

Detection of location of greater palatine foramen (GPF) and its anatomical variations are vital prior to posterior maxillary surgeries. The aim of this study is to determine the anatomical position and size of the greater palatine canal and GPF using cone beam computed tomography (CBCT) scan. To determine the anatomical foramen position, the posterior maxilla area was divided into five regions on the axial view (A to E from the mesial surface of the second molar to distal surface of third molar). The length of the canal was investigated on both coronal and sagittal views. Independent t-test was used to analyze the data. Among 80 females and 68 males, the anatomical position of the GPF was mainly located in region E on the left (55%) and the right (50%), and then, respectively, in region D and region C. The mean diameter of GPF was 4/48 mm on the left and 4/63 mm on the right side (P = 0/01). The average length of the canal on the coronal view was 29.46 mm on the left side and 29.75 mm on the right (P = 0.005). The average length of the canal on the sagittal view was 29.62 mm on the left and 30.02 mm on the right (P = 0.001). The anatomical position of the GPF was primarily located distal to the third maxillary molar. CBCT is a valuable diagnostic tool for evaluation of vital anatomic landmarks in the maxillofacial region prior to surgeries.

An Intraoral OCT Probe to Enhanced Detection of Approximal Carious Lesions and Assessment of Restorations.

Caries, the world’s most common chronic disease, remains a major cause of invasive restorative dental treatment. To take advantage of the diagnostic potential of optical coherence tomography (OCT) in contemporary dental prevention and treatment, an intraorally applicable spectral-domain OCT probe has been developed based on an OCT hand-held scanner equipped with a rigid 90°-optics endoscope. The probe was verified in vitro. In vivo, all tooth surfaces could be imaged with the OCT probe, except the vestibular surfaces of third molars and the proximal surface sections of molars within a "blind spot" at a distance greater than 2.5 mm from the tooth surface. Proximal surfaces of 64 posterior teeth of four volunteers were assessed by intraoral OCT, visual-tactile inspection, bitewing radiography and fiber-optic transillumination. The agreement in detecting healthy and carious surfaces varied greatly between OCT and established methods (18.2–94.7%), whereby the established methods could always be supplemented by OCT. Direct and indirect composite and ceramic restorations with inherent imperfections and failures of the tooth-restoration bond were imaged and qualitatively evaluated. The intraoral OCT probe proved to be a powerful technological approach for the non-invasive imaging of healthy and carious hard tooth tissues and gingiva as well as tooth-colored restorations.

MOLAR CARIES;

Objectives: To identify risk factor of distal surface caries on mandibular secondmolar associated with partially erupted mandibular third molar. Setting: The study wasconducted in the Department of Oral and Maxillofacial Surgery, Liaquat University HospitalJamshoro/Hyderabad from April 2013 to September2013. Methodology: Total 273 patientsof either gender with age 16-45 years had partially impacted mandibular third molar, wereincluded. Diagnosis was made on clinical as well as periapical view and OPG examination.Distance from CEJ of mesial surface of third molar to CEJ of distal surface of second molarwas measured in millimeters. Results: Results about association of caries with other variablesshowed that significant association of caries was observed with gender, winter classification,Pell Gregory (ramus), and angulation with p<0.01. The association of caries was also observedwith age and third molar site with p<0.05. The association was not significant with Pell Gregory(occlusal) and distance with p> 0.05. Conclusion: It was concluded with the results of thisstudy that there was an increased risk of developing dental caries in 2nd molar tooth at distalsurface with risk factor being partially erupted mandibular 3rd molar, mesioangular, class I, levelA, and angulation of more than 30 degrees.

English

Objectives: To identify risk factor of distal surface caries on mandibular secondmolar associated with partially erupted mandibular third molar. Setting: The study wasconducted in the Department of Oral and Maxillofacial Surgery, Liaquat University HospitalJamshoro/Hyderabad from April 2013 to September2013. Methodology: Total 273 patientsof either gender with age 16-45 years had partially impacted mandibular third molar, wereincluded. Diagnosis was made on clinical as well as periapical view and OPG examination.Distance from CEJ of mesial surface of third molar to CEJ of distal surface of second molarwas measured in millimeters. Results: Results about association of caries with other variablesshowed that significant association of caries was observed with gender, winter classification,Pell Gregory (ramus), and angulation with p<0.01. The association of caries was also observedwith age and third molar site with p<0.05. The association was not significant with Pell Gregory(occlusal) and distance with p> 0.05. Conclusion: It was concluded with the results of thisstudy that there was an increased risk of developing dental caries in 2nd molar tooth at distalsurface with risk factor being partially erupted mandibular 3rd molar, mesioangular, class I, levelA, and angulation of more than 30 degrees.

Effect of a novel quaternary ammonium silane cavity disinfectant on durability of resin–dentine bond

ObjectiveThe present study examined the effect of a quaternary ammonium silane (QAS) cavity disinfectant on the viability of human dental pulp cells, dentine bond durability and nanoleakage of simplified etch-and-rinse adhesives. MethodsEtched dentine surface of third molars were randomly divided into two adhesive groups, Adper™ Single Bond 2 and Prime & Bond® NT™. For each adhesive, the teeth were randomly assigned to five cavity disinfectant groups (N=6): Group 1: deionised water (control); Group 2: 2% chlorhexidine (CHX); Group 3: 2% QAS; Group 4: 5% QAS and Group 5: 10% QAS. The cavity disinfectants were applied on etched dentine surfaces for 20s, followed by adhesive application. The bonded teeth were sectioned for bond strength testing at 24h, 6 months and 12 months. Viability of human dental pulpal cells was examined using MTT assay. Bond strength data were analysed using 3-way ANOVA and Tukey test. Interfacial nanoleakage was evaluated after 24h and 12 months and analysed using Kruskal–Wallis test. ResultsSignificant differences in bond strength were observed for the factors disinfectants (p<0.001) and time (p<0.001); while the factor, adhesive, was not significantly different (p=0.203). The 2% QAS cavity disinfectant preserved bond strength of both adhesives and reduced interfacial nanoleakage after 12 months. Cell viability was the lowest for 2% CHX, followed by 2% QAS and the control. ConclusionsThe 2% QAS cavity disinfectant demonstrated greater cell viability compared to 2% CHX, with no adverse effect on immediate bond strength and preserved bond stability over time. Clinical significanceIncorporation of 2% quaternary ammonium silane cavity disinfectant in the resin–dentine bonding protocol enhances the success rate of bonded restorations.

Pattern of mandibular third molar impaction in the Indian population: a retrospective clinico-radiographic survey

The objective of this study was to study incidence of type of impaction of mandibular third molars in the Indian population. Data of 1200 patients examined during a 5-year period were reviewed, which included status of mandibular third molar for inclination, emergence in oral cavity, and prevalence of caries. Radiographically, angulation of tooth, level of occlusal surface of third molar with respect to second molar, relationship between ascending ramus of mandible and distal surface of third molar, and proximity to inferior alveolar nerve were studied. Of 1200 patient data reviewed, 620 (51.77%) were of men and 580 (48.3%) were women in the age group of 20 to 40 years (26.3 years). Mesioangular impaction was most prevalent followed by distoangular. A strong statistical significance was found between gender and ramus relationship. Fifty percent of cases showed proximity to the inferior alveolar nerve, which was more frequent in males (58.3%). Our study highlights mesioangular impaction as the most frequently encountered angulation in impacted teeth.

Prevalence of Third Molars With Caries Experience or Periodontal Pathology in Young Adults

Assess the prevalence of caries experience and periodontal pathology on asymptomatic third molars in young adults. Healthy subjects with four asymptomatic third molars were enrolled in an IRB-approved longitudinal study at two academic clinical centers over a six year period ending in 2002. Data were collected from each subject at enrollment. Full-mouth periodontal probing, 6 sites per tooth, was conducted as a measure of clinical periodontal status. The presence or absence of caries experience (carious lesions or restorations including sealants) in the occlusal surface of third molars and on any surface of first/second molars were assessed by a visual-tactile caries examination and panoramic radiographs. The primary outcome measures were periodontal probing depth, no probing depth ≥4 mm (PD4-) or at least one 4 mm probing depth (PD4+) and caries experience (DFS+ or DFS-). Descriptive statistics. Data were analyzed from 409 subjects who averaged 25 years old. More subjects were female, 53%, or Caucasian, 76%, but African American subjects were well represented, 14%. Most subjects, 89%, were educated beyond high school. More subjects, 55%, had a PD4+ on a third molar as compared to the distal of a second molar (D2M), 46%. Only 11% subjects had a D2M PD4+ without a third molar also affected. Overall, fewer subjects, 24%, were affected by caries on the third molar (DFS+) than on the first/second molar, 73%. Of the subset of subjects with all four third molars (n=229 ) at the occlusal plane (OP), at least one PD4+ was more likely to be detected around a third molar as compared to subjects who did not have all third molars at the OP. In this subset, 26% were affected by both third molar DFS+ and PD4+, and 16% were free of both caries experience and periodontal pathology. In this cross-sectional analysis of data from healthy young adults, periodontal pathology was detected more frequently on asymptomatic third molars as compared to first/second molar teeth; caries experience was detected more frequently on first/second molars as compared to third molars. Sixteen percent of subjects with four asymptomatic third molars at the occlusal plane were free of both periodontal pathology and caries experience.

Bond strength and morphology of enamel using self-etching adhesive systems with different acidities

Objectives:To assess the bond strength and the morphology of enamel after application of self-etching adhesive systems with different acidities. The tested hypothesis was that the performance of the self-etching adhesive systems does not vary for the studied parameters.Material and methods:Composite resin (Filtek Z250) buildups were bonded to untreated (prophylaxis) and treated (burcut or SiC-paper) enamel surfaces of third molars after application of four self-etching and two etch-and-rinse adhesive systems (n=6/condition): Clearfil SE Bond (CSE); OptiBond Solo Plus Self-Etch (OP); AdheSe (AD); Tyrian Self Priming Etching (TY), Adper Scotchbond Multi-Purpose Plus (SBMP) and Adper Single Bond (SB). After storage in water (24 h/37°C), the bonded specimens were sectioned into sticks with 0.8 mm2 cross-sectional area and the microtensile bond strength was tested at a crosshead speed of 0.5 mm/min. The mean bond strength values (MPa) were subjected to two-way ANOVA and Tukey's test (α=0.05). The etching patterns of the adhesive systems were also observed with a scanning electron microscope.Results:The main factor adhesive system was statistically significant (p<0.05). The mean bond strength values (MPa) and standard deviations were: CSE (20.5±3.5), OP (11.3±2.3), AD (11.2±2.8), TY (11.1±3.0), SBMP (21.9±4.0) and SB (24.9±3.0). Different etching patterns were observed for the self-etching primers depending on the enamel treatment and the pH of the adhesive system.Conclusion:Although there is a tendency towards using adhesive systems with simplified application procedures, this may compromise the bonding performance of some systems to enamel, even when the prismless enamel is removed.

Caries Experience and Periodontal Pathology in Erupting Third Molars

This study was conducted to document the prevalence of occlusal caries experience and periodontal pathology for erupting third molars in young adults. The data are from 49 subjects enrolled in an institutional review board-approved trial with at least one third molar below the occlusal plane at baseline that erupted by longest follow-up. Teeth were considered erupted if they reached the occlusal plane. Caries experience on the occlusal surface of third molars was assessed by a visual-tactile examination. At least 1 periodontal probing depth (PD) >or=4 mm in the third molar region was considered indicative of periodontal pathology. The third molar region was defined as the 6 probing sites around third molars and 2 sites on the distal of second molars. The prevalence of third molar caries experience and periodontal pathology at longest follow-up was assessed. Most of the 49 subjects were female (51%), Caucasian (76%), and educated at least through high school (82%). Median age was 20.5 years (interquartile range [IQR] 18.4 to 24.1 years). Median follow-up was 5.1 years (IQR = 3.4 to 6.9 years). At baseline, none of the subjects had occlusal caries experience in a third molar; 51% of subjects had at least 1 PD >or=4 mm in a third molar region. At follow-up, 27% of the subjects had occlusal caries experience in at least 1 third molar that erupted to the occlusal plane; 61% had at least 1 PD >or=4 mm in a third molar region. Twenty-nine percent had occlusal caries in at least 1 third molar at the occlusal plane and at least 1 PD >or=4 mm in a third molar region. Thirty-seven percent had no third molar occlusal caries experience and all third molar region PD <4 mm. For third molars that erupted "late," periodontal pathology was more prevalent than occlusal caries.

Bond strength evaluation of self-etch and total-etch adhesive systems on intact and ground human enamel

The aim of this study was to evaluate the bond strength of adhesive systems to intact and ground enamel. Enamel blocks from buccal and lingual surfaces of third molars were used for bonding procedures. Intact or ground (600-grit SiC paper) enamel surfaces were bonded using two etch&rinse adhesives (Prime&Bond 2.1 and Single Bond), three self-etching primer systems (Optibond Solo Plus SE; Tyrian SPE/One-Step Plus and UniFil Bond) or two self-etching adhesives (One-Up Bond F and Xeno III). A 6-mm composite crown was built on the bonded surfaces and samples were stored for 24 hs at 37°C. Samples were sectioned into 0.9-mm-thick slabs, each slab trimmed to a cross-sectional area of 0.8 mm2 and specimens loaded to failure at a crosshead speed of 0.5 mm/min, using a universal testing machine. Microtensile bond strength data (n=6) were analyzed using Kruskal- Wallis and Dunn tests. Differences in bond strength between intact and ground surfaces were not significant for both etch&rinse adhesives, Tyrian SPE/One-Step Plus, UniFil Bond and Xeno III systems. The enamel surface preparation resulted in higher bond strength for Optibond Solo Plus SE and One-Up Bond F systems. Enamel preparation using 600-grit SiC paper is unlikely to affect resin-enamel bond strengths.

Effects of Dental Probing on Occlusal Surfaces – A Scanning Electron Microscopy Evaluation

The aim of this clinical-morphological study was to investigate the effects of dental probing on occlusal surfaces by scanning electron microscopy (SEM). Twenty sound occlusal surfaces of third molars and 20 teeth with initial carious lesions of 17- to 26-year-old patients (n = 18) were involved. Ten molars of each group were probed with a sharp dental probe (No. 23) before extraction; the other molars served as negative controls. After extraction of the teeth, the crowns were separated and prepared for the SEM study. Probing-related surface defects, enlargements and break-offs of occlusal pits and fissures were observed on all occlusal surfaces with initial carious lesions and on 2 sound surfaces, respectively. No traumatic defects whatsoever were visible on unprobed occlusal surfaces. This investigation confirms findings of light-microscopic studies that using a sharp dental probe for occlusal caries detection causes enamel defects. Therefore, dental probing should be considered as an inappropriate procedure and should be replaced by a meticulous visual inspection. Critical views of tactile caries detection methods with a sharp dental probe as a diagnostic tool seem to be inevitable in undergraduate and postgraduate dental education programmes.

Nd:YAG Laser Influence on Microtensile Bond Strength of Different Adhesive Systems for Human Dentin

The purpose of this study was to investigate the influence of Nd:YAG on microtensile bond strength (microTBS) of different adhesive systems for human dentin. Lasers have been widely used in dentistry. New adhesive systems with different chemical compositions are introduced every year, and it is important to investigate the bonding of new adhesive systems to dentin irradiated with laser. The occlusal surfaces of third molars were removed to obtain flat dentin surfaces. The teeth were randomly divided into six groups. Each adhesive system was applied, according to manufacturers' instructions, to surface dentine with and without Nd:YAG laser irradiation (0.9 W, 15 Hz, 60 mJ per pulse). A block of composite resin was built over the adhesive layer. The specimens were sectioned to obtain 0.70 x 0.70 mm of transversal section. Twenty test specimens were selected for each group, and were then submitted to microTBS on a universal testing machine. According to Student's t-test, for Single Bond, there was no statistically significant difference without (49.32 MPa) and with (47.34 MPa) laser application (p = 0.60). For the Tyrian SPE/One Step Plus, microTBS value with laser (27.09 MPa) was statistically higher than without laser (19.13 MPa), as well as for Adper Prompt L-Pop (22.85 and 13.78 Mpa; p < or = 0.01). The application of Nd:YAG laser to dentin provided an increase in the bond strength values for the Tyrian SPE/One Step Plus and Adper Prompt L-Pop adhesive systems, but did not influence the bond strength values of the Single Bond adhesive system.

Effect of bur type and conditioning on the surface and interface of dentine

The purpose of this in vitro study was to evaluate the surface and resin-dentine interface characteristics of permanent tooth dentine cut with diamond or carbide burs and treated with phosphoric acid (PA) or an acidic conditioner. Labial surfaces of permanent incisors were prepared into dentine with high-speed carbide or diamond burs and divided into two halves. Phosphoric acid 36% was applied on one half and non-rinse conditioner (NRC) was applied on the other half. Ten randomly selected scanning electron microscopy (SEM) fields from each specimen (n = 15) were evaluated. Occlusal surfaces of third molars were divided in two halves for evaluation of the resin-dentine interface. The halves were randomly assigned to one of each conditioner and restored with Prime & Bond NT/Spectrum. Ten specimens were analysed by SEM to evaluate hybrid layer formation and interfacial seal. We observed that surfaces prepared with carbide bur presented less residual smear plugs (P < 0.05) than surfaces prepared with diamond burs. Surfaces conditioned with NRC, which is a smear layer modifier, presented more residual smear plugs than surfaces conditioned with PA (P < 0.05). Treatment with PA resulted in more sealed interfaces than specimens treated with NRC. Within the limitations of this study the results showed that carbide burs leave a surface that is more conducive to bonding than diamond burs.

Incidence of occlusal dental caries in asymptomatic third molars

We sought to determine the incidence of caries experience on the occlusal surface of asymptomatic third molars erupted to the occlusal plane and to examine the association between the prevalence of caries experience in third molars and other molars. Clinical data were collected from healthy patients (ASA Class I, II) with asymptomatic third molars enrolled at 2 clinical centers in an institutional review board-approved clinical trial. All patients with at least one third molar at the occlusal plane and with data at baseline and from the most recent of at least 2 follow-up visits were compared in the analysis. At each visit, the presence or absence of caries experience on the occlusal surface of third molars and on any surface of the first and second molars was recorded during clinical and radiographic examinations. Median time between baseline and the most recent follow-up examination was 2.9 years (interquartile range, 1.6 to 4.0 years). Patients (N = 211) were more often female (55%) and white (79%). Median age at baseline was 26.6 years (interquartile range, 22.7 to 32.6 years). At baseline, 29% of patients were affected by third molar occlusal caries, increasing to 33% at follow-up. Older patients at baseline had more caries in a third molar than those younger than 25 years (43% versus 9%). However, patients who were younger at baseline were more likely to develop caries in third molars at follow-up (9% versus 19%). Mandibular third molars were affected more often than maxillary third molars: 25% versus 19% at baseline and 29% versus 22% at follow-up. At baseline and at follow-up, nearly all patients with third molar caries, 98% and 99%, also had caries in first/second molars. The 3-year caries incidence in third molars erupted to the occlusal plane was highest among younger patients and mandibular teeth. The presence of caries in first/second molars at baseline was highly predictive of the development of third molar caries during the ensuing 3 years.

Occlusal caries experience in patients with asymptomatic third molars

Purpose Our goals were to determine the prevalence of caries experience, carious lesions, or restorations on the occlusal surface, in asymptomatic third molars erupted to the occlusal plane, and to examine the association between caries experience in other molars and third molars within the same mouth and quadrant. Patients and methods Clinical data assessing oral health were collected from healthy patients (ASA I, II). The presence or absence of caries experience on the occlusal surface of third molars and on any surface of the first and second molars was recorded during clinical and radiographic examinations. The occurrence of caries experience for younger and older subjects was compared using the general association Cochran-Mantel-Haenszel statistic and the association of occurrence in the maxilla and mandible by the McNemar test. The association between caries experience in a third molar and caries experience in first and second molars also was assessed. Results Overall, 28% of the 303 patients with at least 1 third molar at the occlusal plane were affected by third molar caries. Patients 25 years or older had more caries experience in a third molar than those younger than 25 years, 39% versus 11% ( P < .0001). Mandibular third molars were affected more often than maxillary third molars, 24% versus 18% ( P < .0001). Nearly all patients, 76 of 80 (95%), with third molar caries experience also had caries experience in first/second molars, but only 80 of 223 (36%) of patients with first/second molar caries experience had a history of third molar caries. Conclusions The prevalence of caries in third molars erupted to the occlusal plane in these young patients was high, but not unique to third molars, particularly in those 25 years of age and older. Although these results provide a baseline description of the association between caries experience in first/second molars and associated third molars, data are needed from longitudinal studies to determine the value of first/second molar caries experience in predicting the risk of caries in third molars.

Effect of erupting third molars on dental caries and gingival health in Finnish students.

The purpose of this study was to assess how the eruptive status of third molars relates to gingival and dental health and, in particular, to the status of the adjacent second molar. One hundred and twenty-three young adults were followed up over a 6-year period, from age 20 to age 26. The status of the second and third molars, and DMF, DMFS, DS, MS, and FS indices, periodontal condition, and salivary acidogenic bacterial counts were assessed. The 6-year DFS increase in relation to second molars was greatest in sextants with unerupted third molars. The percentage of erupting third molars that became carious or had been filled during the study period was 30%. Most new caries lesions or filled surfaces were on mesial surfaces of second molars and occlusal surfaces of third molars. The periodontal condition was best in mandibular sextants in which the third molar was missing. It is concluded that the most favourable situation for upper second molars is if the neighbouring third molar is missing by age 20.

Three-dimensional replicas of pit and fissure morphology in human teeth.

Nuva Seal replicas of pits and fissures from surgically removed unerupted human third molars and premolars, and from erupted premolars extracted for orthodontic reasons, were examined in the scanning electron microscope. The results confirm that the morphology on occlusal surfaces of third molars is extremely variable with numerous pits of considerable length positioned at various angles relative to the fissures. In contrast, the morphology of unerupted and erupted premolars is simpler with fewer and shorter pits positioned perpendicular to the fissure. It is pointed out that fine details of the morphology are lost when reconstructions of the occlusal morphology are made from serial ground sections. However, such reconstructions seem to be less reliable in third molars than in premolars.