A clinical perspective on the anatomical study of digastric muscle.

One of the suprahyoid muscles is the digastric muscle which comprises anterior and posterior bellies joined by an intermediate tendon. Because of its close relationship with the submandibular gland, lymph nodes, and chief vessels of the neck, detailed knowledge about the morphometry of the digastric muscle is essential. The objective of the current cross-sectional evaluative study is to record morphometry along with the digastric muscle's origin, insertion, and variability. Forty human cadavers (25 males and 15 females) were dissected, and the head and neck regions were studied in detail. The attachment of the digastric muscle anterior belly to the digastric fossa of the mandible was noted, and the distal attachment of the posterior belly to the mastoid notch was traced. The length of the anterior belly from the digastric fossa to its intermediate tendon and the length of the posterior belly from the intermediate tendon to its mastoid attachment were measured. There is a fair correlation between the length of the neck and the length of the anterior and posterior belly. The study also identified two cases of bilateral accessory bellies of the anterior belly of the digastric. Normal morphometric data is provided by this study on details of the digastric muscle. It is significant from a clinical and surgical point of view as the muscle lies in proximity to the important structures of the neck.

Evaluation of the efficacy of TruNatomy, ProTaper retreatment, and RaCe file systems in retreatment of moderately curved mandibular molars: An in vitro study.

Context: Endodontic retreatment is the first line of treatment in cases of failed primary endodontic treatment. Although associated with challenges such as incomplete removal of obturating material, increased clinical time, and extrusion of apical debris, endodontic retreatment still has considerable success rate in the general population. Aims: The aim of this study was to evaluate and compare the efficacy of TruNatomy, ProTaper retreatment, and RaCe file systems to remove the obturating material, time taken to remove the obturating material, and apical extrusion of debris using cone-beam computed tomography (CBCT). Settings and Design: In vitro study. Subjects and Methods: Forty-five moderately curved mesiobuccal roots of the mandibular molars were instrumented up to #25, 4% taper and obturated with bioceramic sealer and lateral compaction technique. Teeth were divided randomly into three groups (n = 15). Teeth were retreated with TruNatomy, ProTaper retreatment, and RaCe file systems, respectively. Preretreatment and postretreatment CBCT scans were recorded and percentage of obturating material removed was calculated. Time taken to remove the obturating material and apical extrusion of debris was noted. Statistical Analysis Used: Descriptive statistics including percentage, mean, standard deviation, Tukey's post hoc test, Kruskal-Wallis test, and Mann-Whitney Post hoc test were used. Results: The total time needed for the removal of obturating material was comparatively shorter in the RaCe group, followed by the ProTaper retreatment group and TruNatomy group (P < 0.001). TruNatomy files were significantly better in removing the obturating material than the ProTaper retreatment files (P = 0.04). Statically, no difference between RaCe and TruNatomy files was noted. Apically extruded debris was more in the TruNatomy group than in the RaCe and ProTaper retreatment groups (P = 0.01). Conclusions: All tested endodontic files were effective in removal of obturating material, although none could completely remove the filling material and no system could completely eliminate apical extrusion.

Effects of maternal vitamin deficiency on the microstructure of the maternal hippocampus and behavior in offspring.

Objectives: Nutrition plays a critical role in the brain's function and development. Vitamin B6 in the form of pyridoxal phosphate (PLP) is required for the biosynthesis of several neurotransmitters. As vitamin B6 is not endogenously synthesized, the availability of dietary sources becomes imperative. Due to its contribution to neurological functions, severe vitamin B6 deficiency leads to an increased risk of psychiatric disorders, dementia, and neurodevelopmental disorders. This study aimed to establish a vitamin B6-deficient model in experimental animals and assess the neurodevelopmental effects in their offspring. Methods: Two- to three-month-old female C57BL/6J mice were used in the study. They were randomly divided into control and vitamin B6-deficient groups. The control group was fed a regular diet containing 6 mg vitamin B6/kg and the vitamin B6-deficient group was fed a customized diet containing 0 mg vitamin B6/kg, for 5 weeks (n = 6). After 5 weeks, plasma PLP was assessed. The animals were bred to generate offspring. The dams were killed following weaning, and the hippocampal neurons were quantified using cresyl violet staining. The offspring were assigned the respective diet post-weaning up to 2 months of age. Learning and memory were assessed using the Morris water maze test. Results: The plasma PLP levels confirmed the deficiency in the deficient group compared to the control group. The viable pyramidal neurons in the cornu ammonis 3 (CA3) region of the hippocampus showed a significant difference between the control and deficient groups. Offspring born to deficient dams showed a substantial increase in latency to reach the target quadrant during the probe trial compared to the controls. Conclusion: Vitamin B6 deficiency reduces memory in dams and their offspring, suggesting the importance of vitamin B6 for both brain function and development.

An in vitro radiological evaluation of irrigant penetration in the root canals using three different irrigation systems: Waterpik WP-100 device, passive irrigation, and manual dynamic irrigation systems.

Background: Instrumentation and irrigation of the root canal facilitating effective debridement is considered the most important single factor in the prevention and treatment of endodontic diseases. Aim: The aim of the study was to evaluate the depth of penetration of the irrigant depending on the final activation using Waterpik device modified with NaviTip needle, passive irrigation, and manual dynamic activation using the radiopaque solution in conjunction with digital dental radiography. Materials and Methods: Ninety freshly extracted single-rooted mandibular premolars based on the inclusion and exclusion criteria were used for this study. Access cavity preparation was done for all the samples, and the working length of each sample was determined using a size 10-k file. The radiopaque solution (Urografin) was delivered into (Groups A, B, and C) prepared canal of samples at the rate of 1 ml in 30 s with up-and-down motion. Results: The test results showed that Waterpik WP-100 group showed significantly high infiltration index values as compared to passive irrigation and manual irrigation group at P < 0.002 and P = 0.007, respectively. Conclusion: Sonic irrigation using a Waterpik device modified with a NaviTip needle permits better infiltration of the irrigant.

Serendipitous Discovery of a Benign Obturator Nerve Schwannoma: Case report with a brief clinical review.

Schwannomas are typically benign tumours of the peripheral nerves. However, they seldom arise from the obturator nerve. We report a case of an uncommon swelling (2.5 × 3.5 cm) in a 65-year-old male cadaver, found during a routine dissection session for first Bachelor of Medicine and Surgery students in the Department of Anatomy, Kasturba Medical College, Manipal, India, in 2019. It was seen originating from the left obturator nerve in the pelvis at the level of the sacral promontory. Histopathological investigation revealed a schwannoma. The hypocellular tumour was arranged in a sweeping fascicle pattern with patches of myxoid degeneration. Obturator schwannomas, though rare, can exist in cadavers, as seen in the present case. Hence, it should be considered as a differential diagnosis for clinical cases of pelvic masses and eliminated only after thorough radiological examination. Knowledge about the existence of such schwannomas is therefore essential.

Lateral collateral ligament and anterolateral ligament of the knee - A morphological analysis with orthopedic significance.

BACKGROUND: The lateral collateral ligament (LCL) is the chief stabilizer of the lateral aspect of the knee to varus forces. Studies have confirmed the function of the anterolateral ligament (ALL), which improves the lateral knee stability by preventing excessive internal tibial rotation. Clinically, a persistent instability following anterior cruciate ligament reconstruction may be due to damage to the anterolateral structures. The finding has created a novel interest in anterolateral extra-articular operations. METHODS: This observational, cross-sectional study involved 42 dissected adult knees. The variations in morphology and morphometry of the LCL were identified and classified. The prevalence and the variabilities in the ALL were also noted. RESULTS: The variations in the shape of the LCL were classified into four types: (1) cord, (2) band, (3) mixed, and (4) inverted Y shaped, with a frequency of 69.04, 26.20, 2.38, and 2.38% of specimens, respectively. The cord type measured 50.4 ± 2.7 mm in length and 5 ± 0.9 mm in width. In comparison, the band type measured 50.1 ± 4.2 mm in length and 9 ± 1.6 mm in width. The ALL was identified in four (9%) of the specimens with a mean length of 35 ± 0.9 mm. Two types of ALL were observed, membranous wideband and distinct cord-like ALL. CONCLUSION: The anatomy of the lateral structures of the knee is inconsistent. The study has attempted to classify the different shapes of the LCL along with the frequency and prevalence of the ALL. Orthopedic surgeons and radiologists must note the LCL morphology and prevalence of the ALL due to their clinical implications.

Apical extrusion of debris following the use of single-file rotary/reciprocating systems, combined with syringe or ultrasonically-facilitated canal irrigation.

AIM: The aim of the study is to quantify the amount of debris extrusion after instrumentation with single-file rotary and reciprocating systems used either with conventional irrigation (CI) or passive ultrasonic irrigation (PUI) systems. METHODOLOGY: Sixty extracted human mandibular incisors were randomly assigned to two groups (n = 30); rotary single-file system, One Shape (OS-Group 1) and reciprocating single-file system, WaveOne (WO-Group 2) instruments. The two groups were further subdivided into two subgroups (n = 15); (A) PUI and (B) CI. The apically extruded debris was collected in preweighed glass vials as per the Myers and Montgomery method. After drying, the mean weight of debris was assessed with a microbalance and statistically analyzed using analysis of variance and Student's t-test. RESULTS: The reciprocating file system produced significantly more debris compared to the rotary file system using either of the irrigation systems (P = 0.04). CI produced significantly more (P = 0.02) debris extrusion compared to PUI irrespective of the file system used. CONCLUSION: Under the conditions of this study, both systems caused apical debris extrusion. Rotary single-file system produced less debris extrusion compared to reciprocating single-file system. Use of PUI may be advocated as an alternative to CI, as it causes lesser apical debris extrusion.

A Cadaveric Report on a Giant Ureteric Stone Led Right Hydro Ureter and Severe Hydronephrosis.

BACKGROUND: The ureter shows natural constrictions in its course, and these are the potential site for the impaction of the renal calculus. Giant ureteral stones are associated with insidious growth and late presentation, often leading to renal failure. CASE PRESENTATION: In the present case, we observed a huge ureteric stone obstructing the right ureterovesical junction in a 58 year-old male cadaver. We also found hydroureter distal to the impaction of the calculus, renal damage and severe hydronephrosis on the right side. Histopathological analysis showed conditions of arterio-nephro-sclerosis and eroded ureter secondary to the calculus. Ureteric stones obstruction may result in hydroureter, hydronephrosis and progressive renal damage leading to irreversible renal function. The present case provides valuable information regarding the gross and histopathological alterations in ureteric calculi. CONCLUSION: It further enables clinicians to be armed with the knowledge of preventive approaches to educate patients with previous calculi, or those who may develop in the future.

Persistent fetal superficial middle cerebral vein: an anatomical study.

The superficial middle cerebral vein (SMCV) drains the venous blood from most of the superolateral surface of the brain and drains typically into the cavernous sinus as mentioned in standard textbooks. But the drainage of the SMCV is variable as indicated by various radiological studies. Although variations in the drainage of the SMCV exist, there is a shortage in the literature providing cadaveric evidence for the same. The present study was designed to identify the variations in the drainage pattern of the SMCV in fetal cadavers. During the dissection of formalin-fixed full-term fetuses, deviation in the drainage of the SMCV was observed in five out of 30 cases. In three out of 30 specimens (10%), SMCV was observed draining into superior petrosal sinus; and in two specimens (6.6%) into the transverse sinus. In the remaining specimens, the SMCV drained directly into the cavernous sinus. Knowledge of the variations noted in the present study is essential, not only for diagnosing several diseases involving the cavernous sinus or paracavernous sinuses but also in surgeries of paracavernous sinus lesions and endovascular treatment of arteriovenous fistulas. The SMCV and superior petrosal sinus can be a venous refluxing route in patients with arteriovenous fistulas.

Comparative Evaluation of Efficacy of Platelet-Rich Fibrin and Hank's Balanced Salt Solution as a Storage Medium for Avulsed Teeth: An In Vitro Study.

OBJECTIVE: To compare the efficacy of platelet-rich fibrin (PRF) and Hank's balanced salt solution (HBSS) in the preservation of the periodontal ligament (PDL) cells viability of avulsed teeth. METHODS: A total of 30 non-carious third molars with healthy periodontium, indicated for extraction for orthodontic reasons or chronic pericoronitis, were selected for the study. Samples were divided into four groups: one standard group and one experimental group in addition to two control groups (positive and negative). The positive and negative control group corresponded to immediate and 2-hour dry time respectively. The experimental teeth were bench dried for 40 minutes and then immersed in one of the two storage media: HBSS (standard storage media) and PRF (experimental storage media) for 45 minutes. The teeth in each group were treated with dispase II and collagenase for 30 minutes and later centrifuged for 4 minutes at 1000 rpm. The supernatant was removed with sterile micropipette, the cells were labeled with 0.4% trypan blue, and the number of viable PDL cells was counted with a hemocytometer under a light microscope. One-way Kruskal-Wallis test and Mann-Whitney U test with Boneferroni correction were used for statistical analysis. RESULTS: Results did not demonstrate any statistically significant differences in the viability of PDL cells between the groups with standard and experimental storage media. Group 1 showed a statistically significant difference of mean compared to Groups 2, 3 and 4. When Group 2 was compared with Groups 3 and 4, a P-value>0.05 suggested no statistical significance. CONCLUSION: Within the parameters of this study, HBSS and PRF demonstrated a similar number of viable PDL cells. Hence, PRF could be a used as a good substitute of HBSS as a storage media for avulsed teeth.

Exploration of the fetus with gross anomaly: a case of pseudo prune belly syndrome.

Prune belly syndrome is a rare congenital anomaly usually presented with triad characteristic feature of deficient abdominal muscles, cryptorchidism, and urinary tract anomalies. Here, we present a case with all the characteristic features of prune belly and the associated secondary features which were observed on detailed dissection and exploration of the fetus.

Origin of superior thyroid artery: under the surgeon's knife / Origem da artéria tireoidea superior: sob o bisturi do cirurgião

The major arterial supply to the thyroid gland is from the superior and inferior thyroid arteries, arising from the external carotid artery and the thyrocervical trunk respectively. The external laryngeal nerve runs in close proximity to the origin of the superior thyroid artery in relation to the thyroid gland. The superior thyroid artery is clinically important in head and neck surgeries. Objectives: To locate the origin of the superior thyroid artery, because wide variability is reported. To provide knowledge of possible variations in its origin, because it is important for surgical procedures in the neck. Methods: The origin of the superior thyroid artery was studied by dissecting sixty adult human hemineck specimens from donated cadavers in a Department of Anatomy. Results: The highest incidence observed was origin of the superior thyroid artery from the external carotid artery (88.33%), whereas origin from the common carotid bifurcation only occurred in 8.33%. However, in 3.33% of cases, the superior thyroid artery originated from the common carotid artery and in a single case, the external laryngeal nerve did not cross the stem of the superior thyroid artery at all, but ran ventral and parallel to the artery. Conclusions: It is important to rule out anomalous origin of superior thyroid artery and verify its relationship to the external laryngeal nerve prior to ligation of the artery in thyroid surgeries, in order to prevent iatrogenic injuries. Moreover, because anomalous origins of the superior thyroid artery are only anatomic variants, thorough knowledge of these is decisive for head and neck surgeries

O suprimento arterial principal para a glândula tireoide provém das artérias tireoideas superior e inferior, que têm origem na artéria carótida externa e no tronco tireocervical, respectivamente. O nervo laríngeo externo faz um percurso bem próximo à origem da artéria tireoidea superior em relação à glândula tireoide. A artéria tireoidea superior é clinicamente importante em cirurgias da cabeça e do pescoço. Objetivos: Localizar a origem da artéria tireoidea superior, considerando a ampla variabilidade descrita na literatura; e oferecer informações sobre possíveis variações em sua origem, devido à importância disso para procedimentos cirúrgicos realizados no pescoço. Métodos: A origem da artéria tireoidea superior foi estudada dissecando-se 60 espécimes de hemipescoço adulto de cadáveres humanos doados ao Departamento de Anatomia. Resultados: A maior incidência observada foi da artéria tireoidea superior com origem na artéria carótida externa (88,33%), enquanto a origem na bifurcação da artéria carótida comum ocorreu em apenas 8,33%. No entanto, em 3,33% dos casos, a artéria tireoidea superior teve origem na artéria carótida comum, e em um único caso, o nervo laríngeo externo não cruzou o tronco da artéria tireoidea superior em nenhum momento, embora tenha cursado ventral e paralelamente a essa artéria. Conclusões: É importante descartar origem anômala da artéria tireoidea superior e confirmar sua relação com o nervo laríngeo externo antes da ligadura da artéria em cirurgias da tireoide, para evitar efeitos iatrogênicos. Além disso, como origens anômalas da artéria tireoidea superior são apenas variantes anatômicas, o conhecimento detalhado dessas variações é decisivo para cirurgias da cabeça e do pescoço

Origin of superior thyroid artery: under the surgeon's knife.

BACKGROUND: The major arterial supply to the thyroid gland is from the superior and inferior thyroid arteries, arising from the external carotid artery and the thyrocervical trunk respectively. The external laryngeal nerve runs in close proximity to the origin of the superior thyroid artery in relation to the thyroid gland. The superior thyroid artery is clinically important in head and neck surgeries. OBJECTIVES: To locate the origin of the superior thyroid artery, because wide variability is reported. To provide knowledge of possible variations in its origin, because it is important for surgical procedures in the neck. METHODS: The origin of the superior thyroid artery was studied by dissecting sixty adult human hemineck specimens from donated cadavers in a Department of Anatomy. RESULTS: The highest incidence observed was origin of the superior thyroid artery from the external carotid artery (88.33%), whereas origin from the common carotid bifurcation only occurred in 8.33%. However, in 3.33% of cases, the superior thyroid artery originated from the common carotid artery and in a single case, the external laryngeal nerve did not cross the stem of the superior thyroid artery at all, but ran ventral and parallel to the artery. CONCLUSIONS: It is important to rule out anomalous origin of superior thyroid artery and verify its relationship to the external laryngeal nerve prior to ligation of the artery in thyroid surgeries, in order to prevent iatrogenic injuries. Moreover, because anomalous origins of the superior thyroid artery are only anatomic variants, thorough knowledge of these is decisive for head and neck surgeries.

CONTEXTO: O suprimento arterial principal para a glândula tireoide provém das artérias tireoideas superior e inferior, que têm origem na artéria carótida externa e no tronco tireocervical, respectivamente. O nervo laríngeo externo faz um percurso bem próximo à origem da artéria tireoidea superior em relação à glândula tireoide. A artéria tireoidea superior é clinicamente importante em cirurgias da cabeça e do pescoço. OBJETIVOS: Localizar a origem da artéria tireoidea superior, considerando a ampla variabilidade descrita na literatura; e oferecer informações sobre possíveis variações em sua origem, devido à importância disso para procedimentos cirúrgicos realizados no pescoço. MÉTODOS: A origem da artéria tireoidea superior foi estudada dissecando-se 60 espécimes de hemipescoço adulto de cadáveres humanos doados ao Departamento de Anatomia. RESULTADOS: A maior incidência observada foi da artéria tireoidea superior com origem na artéria carótida externa (88,33%), enquanto a origem na bifurcação da artéria carótida comum ocorreu em apenas 8,33%. No entanto, em 3,33% dos casos, a artéria tireoidea superior teve origem na artéria carótida comum, e em um único caso, o nervo laríngeo externo não cruzou o tronco da artéria tireoidea superior em nenhum momento, embora tenha cursado ventral e paralelamente a essa artéria. CONCLUSÕES: É importante descartar origem anômala da artéria tireoidea superior e confirmar sua relação com o nervo laríngeo externo antes da ligadura da artéria em cirurgias da tireoide, para evitar efeitos iatrogênicos. Além disso, como origens anômalas da artéria tireoidea superior são apenas variantes anatômicas, o conhecimento detalhado dessas variações é decisivo para cirurgias da cabeça e do pescoço.

An analysis of cyclic fatigue resistance of reciprocating instruments in different canal curvatures after immersion in sodium hypochlorite and autoclaving: An in vitro study.

AIM: The aim of this study is to assess the effect of sodium hypochlorite and sterilization on the cyclic fatigue resistance of two reciprocating nickel-titanium files using a rotary and a reciprocating motor. MATERIALS AND METHODS: Totally, 160 Reciproc and Wave One files were tested. The eighty files of the same brand were assigned into four groups (n = 20). These four groups were further divided into two subgroups, 1a and 1b, 2a and 2b, 3a and 3b, 4a and 4b consisting of ten files in each group. 2.5% NaOCl for 5 min, 2.5% NaOCl for 5 min + 1 cycle of autoclave sterilization, 2.5% NaOCl for 5 min + 5 cycles of autoclave sterilization, no sterilization (control). Groups 1a, 2a, 3a, and 4a were subjected to 30° and Groups 1b, 2b, 3b, and 4b were subjected to 60° canal curvature. RESULTS: Intergroup comparison reveals that there is an increase in cyclic fatigue resistance from the first cycle to the fifth cycle of autoclave which is statistically significant. CONCLUSION: Reciproc and Wave One showed reduced cyclic fatigue resistance on immersion in NaOCl for 5 min. Multiple autoclaving cycles significantly increased the cyclic fatigue resistance of Reciproc file system in both the curvatures. There was a decrease in cyclic fatigue resistance for Wave One after multiple autoclaving at 60° curvature which was statistically significant.

Effect of dentin on the antimicrobial efficacy of 3% sodium hypochlorite, 2% chlorhexidine, 17% ethylenediaminetetraacetic acid, and 18% etidronic acid on Candida albicans: An in vitro study.

AIM: The aim of this study was to evaluate the effect of dentin on the antimicrobial efficacy of 3% sodium hypochlorite, 2% chlorhexidine, 17% EDTA and 18% etidronic acid against C. albicans. METHODOLOGY: Dentin powder was prepared from mandibular first premolar using electrical grinder and sterilized. 3% NaOCl, 2%CHX, 17% EDTA and 18% etidronic acid were tested against C. albicans in the presence and absence of dentin, in eppendorf tubes. Group 1 (presence of dentin):- 100ul dentin powder + 100ul C. albicans suspension + 100ul irrigating solution. Group 2 (absence of dentin):- 100ul C. albicans suspension+ 100ul irrigating solution. CONTROL GROUP: - 100ul C. albicans suspension.+ 100ul sterile saline Suspension was thoroughly mixed, submitted for serial dilution upto10-5 after 1 min and colony forming units were counted. RESULTS: In group 2 (without dentin powder), 3% NaOCl and 2% CHX showed the lowest bacterial count compared to group 1 (with dentin powder). Dentin had a significant inhibitory effect on 3% NaOCl (P < 0.001) and 2% CHX (P<0.001). 17% EDTA showed lowest bacterial count in group 1 (with dentin powder) compared to group 2 (without dentin powder). 18% Etidronic acid showed similar bacterial counts in the both the groups. No reduction was observed in the control group. CONCLUSION: NaOCl & EDTA showed measurable antimicrobial effect even in the presence of dentin which can be promising in the reduction of C. albicans in root canal therapy.

Disinfection of gutta-percha cones using three reagents and their residual effects.

AIMS AND OBJECTIVES: The purpose of this study was to compare the efficacy of 5.25% sodium hypochlorite, 2% chlorehexidine and MTAD in disinfecting gutta-percha cones and to analyze the surface topography of gutta-percha cones after the rapid chemical disinfection procedure. MATERIALS AND METHODS: Gutta-percha cones were immersed in suspensions of Enterococcus faecalis and Staphylococcus aureus separately. The cones were then immersed in 5.25% NaOCl, 2% CHX and MTAD for 30 seconds, 1 minute and 5 minutes separately. The disinfected cones were then incubated in thioglycollate media for 7 days. The thioglycolate media was sub-cultured and colony forming units were counted. For topographical examination of gutta-percha cones, the cones were immersed in respective solutions for one minute and allowed to air dry for 30 minutes after rinsing or without rinsing the cones with distilled water. The topography of the cones were then analyzed under SEM. Data was statistically analyzed using one way anova. RESULTS: MTAD was found to be the most effective disinfecting solution. The topographical examination of GP cones found some deposits after the disinfection procedure in every group. These deposits were removed when the GP cones were rinsed with distilled water. CONCLUSIONS: MTAD possesses superior bactericidal activity when compared with NaOCl and CHX and a final rinse with distilled water is essential after the disinfection procedure.

Evaluation of smear layer removal from ultrasonically prepared retrocavities by three agents.

OBJECTIVES: To evaluate the efficacy of 35% orthophosphoric acid, 24% ethylenediaminetetraacetic acid (EDTA) and 10% citric acid in the removal of smear layer from retrocavities prepared with ultrasonic retro-tips using scanning electron microscopy. MATERIALS AND METHODS: Root canals of fifty single-rooted teeth were cleaned, shaped, and obturated with gutta-percha and AH plus sealer. The apical 3 mm of each root was sectioned with a diamond disc and retrograde cavities were prepared with Kis # 1 ultrasonic retro-tips to a depth of 3 mm. Retro cavities in Group I were treated with a gel of 35% orthophosphoric acid for 15 seconds, Group II were treated with a gel of 24% EDTA at neutral pH for 2 minutes, and Group III were treated with a gel of 10% citric acid for 2 minutes, followed by 1 minute rinsing with distilled water for all groups. The samples were prepared for scanning electron microscopic observation. Scoring was performed for the presence of the smear layer on the walls of the retrocavity. RESULTS: In the orthophosphoric acid group, it was observed that all dentinal tubules were open in 70% of the samples. The majority of analyzed samples in EDTA and citric acid group showed dentinal tubules covered with the smear layer. CONCLUSIONS: Application of 35% orthophosphoric acid gel for 15 seconds on retrocavities prepared with ultrasonic retro-tips is the most effective means for removal of smear layer.

Evaluation of effect of different cavity disinfectants on shear bond strength of composite resin to dentin using two-step self-etch and one-step self-etch bonding systems: a comparative in vitro study.

AIM AND OBJECTIVES: To evaluate the effect of 2% chlorhexidine, 2% sodium hypochlorite, 3% hydrogen peroxide on shear bond strength of composite resin to dentin using two-step and onestep self-etch bonding systems and to study the mode of failure of specimens under stereomicroscope. MATERIALS AND METHODS: Eighty extracted sound human posterior teeth were used. The occlusal surfaces were ground to expose the dentin and were then randomly divided into 4 main groups. In group I, no cavity disinfectant was used and served as control. In groups II, III, IV, 2% chlorhexidine, 2% sodium hypochlorite and 3% hydrogen peroxide were used as cavity disinfectants respectively. Each group was then divided into two subgroups of 10 teeth each according to the bonding agent used, two-step self-etch (Adper SE Plus) and one-step self-etch (Adper Easy One) respectively. A transparent cylindrical plastic tube was loaded with microhybrid composite and placed over the dentin and light cured for 40 seconds. The specimens were subjected to shear stress in the universal testing machine. RESULTS: Pretreatment with 2% chlorhexidine, 2% sodium hypochlorite and 3% hydrogen peroxide, had a negative effect on the shear bond strength of self-etching bonding systems. CONCLUSION: The highest bond strength was found in 2% chlorhexidine group followed by 2% sodium hypochlorite group and the lowest bond strength was found in 3% hydrogen peroxide group. CLINICAL SIGNIFICANCE: All three cavity disinfectants used in this study reduced the shear bond strength and hence should be used with caution.