Erosion Of Canal Research Articles

Correlation of Pre-operative Temporal Bone CT Scan Findings with Intraoperative Findings in Chronic Otitis Media: Squamous Type.

To correlate the pre-operative Temporal Bone High Resolution Computer Tomography (HRCT) Scan findings with intraoperative findings in Chronic Otitis Media-Squamous type. This prospective, correlative, observational study was done at Department of Otorhinolaryngology and Head and Neck Surgery, Tribhuvan University Teaching Hospital, Kathmandu. 156 patients underwent mastoid surgery under General Anaesthesia from October 2017 to November 2018. Ethical committee approval taken from the institutional review committee. Informed consent regarding the study was taken prior to surgery. The peroperative findings were correlated with preoperative HRCT findings. Cohen's kappa coefficient (k-value) was used to estimate the degree of correlation. Statistical analysis was done using SPSS version 25. Total 156 patients between 8 and 70years of age were enrolled in the study. Presence of cholesteatoma/granulation on HRCT scan was found with 100% sensitivity with k-value of 0.569 denoting fair agreement. Regarding ossicular status, malleus showed maximum k-value of 0.525 with sensitivity of 81.3% followed by stapes and incus with k-value of 0.308 and 0.380 and sensitivity of 68.3% and 70.2% respectively. Sinus plate status showed perfect radiosurgical agreement with k-value of 1.0 and sensitivity and specificity of 100%. Bony facial canal demonstrated slight agreement with k-value of 0.506 and sensitivity of 45.8%. Dural plate status showed fair agreement with k-value of 0.503 and sensitivity of 38.9%. For Lateral Semicircular Canal (LSCC) erosion, we found very good agreement with k-value of 0.893 with sensitivity of 90.9%. Preoperative HRCT scan temporal bone correlates well for the detection of disease presence and shows good radiosurgical agreement for sinus plate erosion, LSCC erosion but fair agreement for dural plate erosion and malleus erosion. Plain HRCT scan with 3-D reconstruction is a poor predictor of bony facial canal, incus and stapes erosion.

St Lawrence Seaway: Eastern Great Lakes, the Niagara River and Welland Canal Replacement, Maintenance and Protection

The Eastern Great Lakes region covers 51,000 square km of land, and is home to 15 million people. This region is rich in natural resources, industry and agriculture, and forms the heartland of both Canada and the United States. The development of this region has a history that is closely tied to waterways, and the development of canals that promoted growth and prosperity. The St. Lawrence Seaway connects Western and Eastern Great Lakes to the St Lawrence River and the Gulf of Saint Lawrence. The New York State Canal and the St. Lawrence Seaway were linked by the Oswego canal and provided a shorter route for cargo via barges to New York City. The New York State (NYS) Barge Canal and the St. Lawrence Seaway provided pathways for the settlement of the Eastern Great Lakes. Lake Erie drains into Lake Ontario via the Niagara River but the river was not navigable due to the obstacles of Niagara Falls and the Niagara Escarpment. Until the 1820s ships could not travel into Lake Erie. It was not possible to engineer a bypass of Niagara Falls with a series of locks due to the 100 m high Niagara escarpment. This escarpment obstacle to Niagara River navigation was overcome in 1829 with the completion of the first of four Welland Canals with locks 40 kilometers west of the Niagara River through the glacial till and alluvium that overlays the Niagara Escarpment. This permitted ocean going ships to enter Lake Erie and to continue on to Lake Michigan, Lake Huron and Lake Superior. The Eastern Great Lake shorelines, river banks and canals are actively eroding as a consequence of high surface water levels and flooding. The settlement of millions of people into the Eastern Great Lakes via the NYS Barge Canal and St. Lawrence Seaway migration pathways have created environmental and natural resource risks and challenges. These challenges and risks include deterioration of the Fourth Welland Canal and the need to replace it with the Fifth Welland Canal, industrial and urban wastewater disposal, shoreline, river bank and canal erosion as results of high water levels, the building of structures on the shoreline banks, invasive species and flooding.

Radio-surgical correlation of chronic suppurative otitis media

<p class="abstract"><strong>Background:</strong> Chronic suppurative otitis media (CSOM) because of disease nature and location of vital structures like middle ear ossicles, facial nerve, and lateral semicircular canal poses clinical as well as radiological challenge in diagnosis, especially the squamosal variety. Hence this study to evaluate radio-surgical correlation in cases of CSOM.</p><p class="abstract"><strong>Methods:</strong> We retrospectively analysed 92 case records who met the inclusion criteria. Their pre-operative high-resolution computed tomography (HRCT) temporal bone imaging was evaluated for erosion of the ossicular chain and the fallopian canal. This was correlated with the surgical findings noted intra-operatively. The appropriate statistical analysis was carried out. The radio-surgical correlation was evaluated by Cohen’s kappa value. </p><p class="abstract"><strong>Results:</strong> The kappa value for status of ossicular chain was 0.805 and 0.384 for status of fallopian canal. HRCT imaging had a positive predictive value and negative predictive value of 94.3% and 85.3% respectively, in detecting ossicular chain erosion. In detecting fallopian canal erosion, HRCT showed a sensitivity of 33.3%. Analysing the individual ossicles, we found kappa to be 0.266 for malleus, 0.463 for incus and 0.827 for stapes.</p><p class="abstract"><strong>Conclusions:</strong> There was excellent radio-surgical correlation for ossicular chain erosion while it was poor for fallopian canal erosion. HRCT showed excellent radio-surgical correlation for stapes, moderate for incus and poor for malleus. In-spite of its shortcomings in differentiating cholesteatoma and non-cholesteatomatous pathologies of the middle ear cleft, HRCT imaging plays a key role in assessing the status of the ossicles and fallopian canal.</p><p> </p>

Prediction of Canal Erosion on Tidal Swamp Delta Telang I, Banyuasin Regency, South Sumatra

Surface water dynamics at swamp region either in tertiary compartment also at canals very influenced by several conditions, among others: total rainfall, hydro-topography, potential high water overflow, potential drainage, water order network condition, and water order building operation. For that entire components must be evaluated and at analysis to support plants amount of water required fulfillment efforts. The canals need observation data directly at field so that can accurate observation data. In the manner likes this need time, energy and cost big enough. Therefore, computer model use to guess and evaluate network performance is a correct solution. Related to troubleshoot above, so necessary existence to watchfulness besides to evaluate existing drainage system performance in water face control at also necessary channel stability analysis in the effort support operation and channel maintenance. Supposed to this watchfulness can describe according to intact process the happening of erosion and sedimentation at channel, environment service aspect and qualitatively model constructively SOBEK software can explain sedimentation dynamics in canals at tidal swamp region.

Comparison of High Resolution Computed Tomography with Intraoperative Findings in Patient with Chronic Suppurative Otitis Media, NAMS, Bir Hospital, Kathmandu, Nepal

Introduction: Chronic suppurative otitis media (CSOM) is an important cause of middle ear disease and its complications challenge both otologist and radiologist. The major benefit of HRCT is an excellent visualization of the osseous structure by means of special algorithms. This study compares the HRCT with intraoperative findings in patients with CSOM.
 Methods: This is an observational descriptive study conducted at NAMS Bir Hospital. Total of 30 patients, referred for HRCT from the department of ENT were studied. Comparison of HRCT findings was done with intraoperative findings regarding the status of EAC, ossicular chain, bony plate, inner ear structure and facing nerve canal was done, considering intraoperative findings as the gold standard.
 Results: Out of 30 patients, 16 patients had CSOM with cholesteatoma and 14 patients had CSOM without cholesteatoma. HRCT presented sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 87.5%, 85.7%, 87.5%, 85.7% and 86.7% respectively in diagnosing CSOM with cholesteatoma. HRCT presented sensitivity and specificity of 85.7% and 87.5% in identification of malleus erosion, sensitivity and specificity of 86.7% and 80%, in the identification of incus erosion. HRCT showed the specificity of 85% with relatively low sensitivity of 70% in identification of erosion of stapes. HRCT showed a sensitivity of 100% and specificity of 85.7%. HRCT presented sensitivity and specificity of 83.3% and 95.8% in diagnosing tegmen tympanum erosion. HRCT showed the highest sensitivity (100%) and specificity (100%) in diagnosing erosion of sigmoid sinus plate and mastoid cortex. HRCT showed relatively low sensitivity of 66.7% and 75% in diagnosing erosion of LSCC and facial canal respectively. HRCT detected soft tissue mass in the middle ear/mastoid in all 30 patients of CSOM. Hence, the sensitivity, specificity, positive predictive value and negative predictive value of HRCT for soft tissue mass in the middle ear and mastoid, all were 100%.
 Conclusion: The HRCT has a valuable role in preoperative evaluation of a case of CSOM. It has high sensitivity in diagnosing CSOM with cholesteatoma. However, HRCT has relatively low sensitivity for LSCC and facial nerve canal erosion.

A Wolf in Sheep’s Clothing: Keratosis Obturans Causing Facial Nerve Palsy - A Case Report with Review of the Literature

Keratosis obturans is a benign disease caused by layered impaction of wax within the external auditory canal. It presents with acute onset of pain and ear blockade. The current report discusses a 24-year-old male patient with recurrent unilateral keratosis obturans associated with facial canal erosion and resulting in facial palsy. A detailed review of the literature is presented. Keratosis obturans can behave aggressively, resulting in significant erosion of the bone and intratemporal structural damage and complications. Timely intervention is vital.

Preoperative temporal bone HRCT and intra-operative findings in middle ear cholesteatoma: a comparative study

<p class="abstract"><strong>Background:</strong> Middle ear cholesteatoma is a potentially dangerous condition owing to the varied extra-cranial as well as intra-cranial complications, it can be associated with. Clinical suspicion and otologic examination sufficiently identifies the pathology but its entire extent and spread is delineated by HRCT examination only, which is presently the ‘Gold Standard’. In this study we tried evaluate the efficacy of HRCT temporal bone in depiction of extent of pathology in cases of cholesteatoma of middle ear and we tried to verify the findings on HRCT imaging with intra-op findings.</p><p class="abstract"><strong>Methods:</strong> A prospective observational study comprising of 50 patients suspected of middle ear cholesteatoma was carried out at a tertiary care hospital in Lucknow, India. Pre-op evaluation with bilateral temporal bone HRCT imaging followed by suitable surgery was performed. Important pre-operative HRCT and intra-operative surgical findings were correlated for statistical significance. </p><p class="abstract"><strong>Results:</strong> Mesotympanum involvement (96%) was the most common HRCT finding as far as location and extent were concerned and incus erosion (70%) was the most common bony complication. A high sensitivity and specificity (82% -100%) of HRCT was found in detection of Erosion of scutum, tegmen tympani and incus. For findings such as stapes erosion and facial canal erosion on HRCT, a sensitivity of 68.4% and 50% respectively was found when compared to intra-op findings.</p><p><strong>Conclusions:</strong> HRCT temporal bone is a useful tool in pre-operative delineation of the extent of cholesteatoma and the recognition of its manifestations and complications. It can help the operating surgeon in appropriate surgical planning.</p>

Role of high resolution computed tomography of temporal bone in preoperative evaluation of chronic suppurative otitis media

<p class="abstract"><strong>Background:</strong> Chronic suppurative otitis media (CSOM) is a common condition seen in patients attending ENT department. The diagnosis of cholesteatoma is usually made on otologic examination. The necessity for HRCT imaging in an uncomplicated case is controversial. The objective was<strong> </strong>to evaluate preoperative HRCT temporal bone and to determine its’ usefulness in patients with Chronic suppurative otitis media (CSOM) undergoing surgery.</p><p class="abstract"><strong>Methods:</strong> This study was a prospective study involving 30 cases of CSOM with cholestaetoma. All the patients underwent pre-operative HRCT screening followed by surgical exploration of middle ear cleft. Pre-operative CT scan and intra-operative findings recorded and compared. </p><p class="abstract"><strong>Results:</strong> Out of total 30 patients of CSOM, 16 (53%) were males and (90%) presented with chief complaints of otorrhoea. HRCT scan was found to be very sensitive (100%) in detecting cholesteatoma in middle ear cleft but differentiation between granulations or cholesteatoma wasn’t possible. HRCT satisfactorily delineated ossicular erosion except stapes suprastructure erosion which had 81.8% sensitivity and specificity 88.88%. For bony boundaries of middle ear, HRCT showed very high sensitivity and specificity for detecting scutum erosion, tegmen erosion, mastoid cortex erosion, jugular bulb dehiscence and bony external auditory canal erosion. It was moderately sensitive for LSCC Erosion (75%), Facial canal erosion (80%) and Sinus plate erosion (85.7%).</p><p class="abstract"><strong>Conclusions:</strong> These results indicate that preoperative CT temporal bone scan of patients with CSOM serves as an important guide in surgical approach for otolaryngologists, although there are limitations in evaluation of the CT results.</p>

Silent keratosis obturans causing exposure of the facial nerve

Keratosis obturans is a condition of the external ear canal and could be described as an intensification of keratin plugs within the canal. The disease may lead to erosion and widening of the external auditory canal. Undiagnosed wax keratosis may lie passively for a long period without revealing any symptoms. We report a case that was largely silent causing exposure of the vertical segment of the facial nerve.

Is Routine Use of High Resolution Computerized Tomography of Temporal Bone in Patients of Atticoantral Chronic Suppurative Otitis Media without Intracranial Complications Justified?

Role of high resolution computerized tomography (HRCT) of temporal bone is established in cases of atticoantral chronic suppurative otitis media (CSOM) with intracranial complications. Routine use of HRCT in management of patients of atticoantral CSOM without intracranial complications has been an issue of debate. The aim of this study was to evaluate the routine use of HRCT of temporal bone in such cases. This study was a prospective study done at LG hospital, AMC MET Medical College, Ahmedabad to evaluate and compare the temporal bone findings in HRCT and intraoperative findings in 100 patients with atticoantral CSOM. All patients underwent HRCT screening followed by surgical exploration of middle ear cleft. In extent of disease HRCT showed very high sensitivity and specificity for epitympanum (100, 94%) and mesotympanum (98, 98%) areas. It gave valuable information of disease extent in hidden areas like sinus tympani and facial recess of mesotympanum. HRCT satisfactorily delineated malleus and incus erosion but had 75% sensitivity for detecting erosion of stapes suprastructure, though specificity was of 97%. For bony anatomical landmarks HRCT showed very high sensitivity and specificity for detecting erosion of lateral semicircular canal, tegmen tympani and sinus plate. Detection of facial canal erosion on HRCT had moderate sensitivity of 75%. We concluded that routine use of HRCT is justified as a reliable preoperative tool in patients with atticoantral CSOM without intracranial complications and it helps to plan type of surgical intervention. HRCT has limited role to distinguish between granulations and cholesteatoma and also to delineate stapes supra structure and facial nerve canal.

An unusual case of simultaneous left glomus vagale, jugulare and tympanicum tumor

A 49-year-old male who attended our hospital due to a history of left hearing loss over a period of 2 years, associated to otalgia, and vertigo to which bleeding in the left ear and facial paralysis had been added in the last 4 months. He reported the simultaneous onset of a left-sided neck swelling with slow growing. After this, he developed loss of sensation of taste on the posterior third of the tongue and swallowing dysfunction, dysphonia, atrophy of the trapezius and sternocleidomastoid muscle and deviation and atrophy of tongue toward the affected side. On physical examination, the mass was found to be painless, soft, pulsating and semifixed. During the otoscopic examination, a pulsatile erythematous lesion of vascular appearance was noted in the external auditory canal. The audiometric test revealed severe left mixed hearing loss. A Doppler ultrasound was performed, which revealed a hypervascularized tumor in the left-sided neck that extended to the skull base. An axial and coronal computerized tomography (CT) scan was taken, revealing a soft tissue lesion extending from the border of II and III neck region to the middle ear and external auditory canal, causing large jugular bulb, hypoglossal canal and temporal bone erosion. This mass avidly enhanced after CT angiography. Following the results of preoperative examinations, diagnosis of simultaneous left glomus vagale, jugulare and tympanicum was confirmed. As the tumor was unresectable, the patient received fractionated radiotherapy associated with iterative stereotactic radio surgery. The patient has been stable over the last two years.

Correlation of high-resolution computed tomography temporal bone findings with intra-operative findings in patients with cholesteatoma

Aim: To evaluate the role of high-resolution computed tomography (HRCT) temporal bone in patients with active squamosal chronic otitis media (COM). Materials and Methods: Totally, 47 patients with active squamosal COM underwent preoperative HRCT temporal bone followed by surgery. Their intra-operative findings were considered as the gold standard and were compared and correlated with the radiological findings, to calculate the sensitivity, specificity, positive and negative predictive value of HRCT temporal bone. Results: According to the present study, HRCT was highly sensitive for detecting mastoid pneumatization, soft tissue extension, ossicular erosion, tegmen and sigmoid sinus erosion, and less sensitive for fallopian canal erosion and lateral sinus fistula. It was specific for all these parameters. Conclusion: The present study concludes that HRCT can be recommended not only in cases suspected with potential complications but also in all cases of COM to know the extent of disease, varied pneumatization, and the presence of anatomical variations, which should alert the clinician and guide in surgical approach and treatment plan.

Limits of conventional temporal bone computed tomography in the management of cholesteatoma otitis media: Report of 96 cases

Cholesteatoma is a dangerous chronic otitis media, with keratine accumulation causing bone erosion and invasive damages. Computed tomography (CT) is commonly indicated to evaluate the extension and the complications of cholesteatoma. In 96 patients with cholesteatoma otitis, preoperative CT data were compared with surgical findings using the sensitivity, specificity, and the predictive value of a CT-scan for anatomical structures. A CT scan offers an adequate anatomical conformation of the tympanomastoid cavities. The lysis of the tegmen (Se = 61%, Sp = 79%) and the erosion of the scutum (Se = 100%, Sp = 51%) are well visualized on coronal sections. CT is very sensitive to objective ossicular chain lysis (Se = 90%) but with a low specificity (Sp = 71%). The performance of CT in the facial canal erosion (Se = 45%, Sp = 78%) and in the labyrinthine fistulae (Se = 46%, Sp = 98%) was insufficient with the conventional scanning machine used. A CT-scan should be a routine exam before cholesteatoma surgery, but with improved resolution, and therefore sensitivity, to characterize all middle ear structures and complications of the disease.

Pre-operative high resolution computed tomography scans for cholesteatoma: Has anything changed?

ObjectiveCT temporal bone scans are often performed to aid in surgical planning and management of cholesteatomas. With improvements in the resolution of CT scans today, it is now possible to obtain more information from these scans than before. The aim of this study is to compare findings on high resolution CT (HRCT) temporal bone scans to intra-operative findings, so as to determine how well various middle ear structures are assessed by HRCT scanning. Study designRetrospective study. SettingOtology clinic of a tertiary otolaryngology centre. Subjects and methods32 mastoidectomies performed by a single otologist for clinically confirmed cholesteatoma were included. Correlation of CT and intra-operative findings on the status of structures including the ossicles, semicircular canals, facial canal and tegmen was analysed using kappa and AC1 statistics. ResultsIn all patients, a soft tissue mass with bony erosion in keeping with a cholesteatoma was seen on CT. Radiosurgical agreement was excellent for the presence of semicircular canal erosion (k=0.89, AC1=0.96), facial canal dehiscence (k=0.74, AC1=0.76), tegmen erosion (k=0.76, AC1=0.92) and malleus erosion (k=0.76, AC1=0.85). It was good for incus erosion (k=0.71, AC1=0.92) and stapes erosion (k=0.63, AC1=0.73). ConclusionThere was good to excellent radiosurgical agreement in the assessment of the status of various middle ear structures. Improvement in radiosurgical agreement from existing studies in the literature was noted. This was especially true for features such as facial canal dehiscence. With technological advancements, CT temporal bone scans appear even more valuable for evaluation of patients prior to cholesteatoma surgery.

Erosion on the Secondary Canal of Reclaimed Agriculture Tidal Lowlands Telang I Banyuasin Regency

Canal erosion is one of the technical issues in tidal lowland agriculture. It is influenced by water flow in the canal under a designated water network system. This study aims at exploring several aspects related to the erosion at the secondary canal in tidal lowlands of Delta Telang I, Banyuasin District, South Sumatra. A survey was conducted to measure canal profiles related to water flow, observe grain size and sediment transport in secondary canal and its implication on the operation and maintenance of water infrastructures. Results indicate that majority of secondary canals are unstable in relation to water flow. Sediment size in both SPD and SDU canals is categorized as non-cohesive. Operation and maintenance should be directed towards achieving stable canal to fulfil crop water requirement

A comparison of residual smear layer and erosion following different endodontic irrigation protocols tested under clinical and laboratory conditions

Objective. To compare the smear layer removal efficacy and erosive effects of different irrigation protocols under clinical and laboratory conditions. Materials and methods. Mandibular third molars (n = 32) of 30–45 year-old patients were instrumented with rotary files and were randomly assigned to one of the following groups for final irrigation: (1) 5.25% NaOCl; (2) 17% EDTA; and (3) BioPure MTAD. Thereafter, the teeth were immediately extracted and processed for micromorphological investigation. In vitro specimen pairs were prepared by repeating the clinical experiments on freshly-extracted mandibular third molars. To compare open and closed systems, laboratory experiments were repeated on 32 additional teeth with enlarged apical foramen. The cleanliness of the root canals and the extent of erosion were assessed by environmental scanning electron microscopy. Results. Specimens prepared under clinical and laboratory conditions had similar cleanliness and erosion scores (p > 0.05). Under both conditions, the tested solutions were more effective in removing the smear layer in the coronal and middle regions than in the apical one. Comparison of closed and open systems showed similar levels of cleanliness and erosion in all regions (p > 0.05), with the exception of 17% EDTA showing significantly higher levels of cleanliness and erosion in the apical third of open-end specimens. Conclusions. Based on clinical correlates of in vitro root canal cleanliness and erosion, laboratory testing of root canal irrigants on extracted teeth with closed apices can serve as a reliable method to simulate the clinical condition. EDTA was the most effective final irrigation solution in removing the smear layer at the expense of yielding the greatest erosive effect.

Evaluation of Temporal Bone Cholesteatoma and the Correlation between High Resolution Computed Tomography and Surgical Finding

BackgroundAcquired cholesteatomas are commonly seen in patients less than 30 years. There is a typical history of recurrent middle ear infections with tympanic membrane perforation. The diagnosis of cholesteatoma is usually made on otologic examination.ObjectiveThe aim of the work was to study the role of high resolution computed tomography (HRCT) in detecting, evaluating, and diagnosing middle ear cholesteatoma.Patients and methodsThis was a prospective study that included 56 consecutive patients with chronic suppurative otitis media, unsafe type cholesteatomas. Each patient was subjected to full clinical evaluation, and HRCT examination. Intravenous contrast media was used in some patients with suspected intracranial complication. Preoperative radiological data were correlated with data related to surgical findings.ResultsThe study showed that a high incidence of cholesteatoma in the third decade of life. The scutum and lateral attic wall were the most common bony erosions in the middle ear bony wall (64.3%), and the incus was the most eroded ossicle in the middle ear (88.2%). Sclerosing of mastoid air cells were encountered in 60.7% of patients and the lateral semicircular canal was affected in 9%, while facial canal erosion was found in 21.4%. Temporal bone complications are more common than intracranial complications.HRCT findings were compared with operative features; the comparative study included the accuracy and sensitivity of HRCT in detecting cholesteatoma (92.8%), its location and extension (96.4%), ossicular chain erosion (98%), labyrinthine fistula and intracranial complications (100%).ConclusionThe important role of HRCT scannig lies on the early detection of cholesteatoma, and more conservative surgical procedures can be used to eradicate the disease.

Canal Wall‐up Tympanomastoidectomy: Recurrence Factors

Objective: Canal wall-up tympanomastoidectomy is gaining popularity in the treatment for cholesteatoma. The choice remains controversial because of the significant recurrence rate of this disease. We aimed to analyze tympanomastoidectomy success rate, to establish eventual predictive factors for failure, and to evaluate the computed tomography (CT) scan’s value in this pathology. Method: We performed a retrospective cohort study regarding all patients submitted to tympanomastoidectomy for cholesteatoma at the otolaryngology department of Hospital São José, Lisbon, from January 1, 2005, to December 31, 2009. Clinical and demographic data were obtained from medical records. Results: One hundred nineteen patients were submitted to tympanomastoidectomy. In most cases, preoperative CT scans showed cholesteatoma in the attic (50%) and large extension of the disease (tegmen, semicircular or fallopian canal erosion in 51%), not always confirmed during surgery (75%). Sixty percent had a canal wall-down procedure. The overall postoperative air-bone gap was within 20 dB in 44%. Second-look surgery was performed in 24 patients: the overall recurrence rate was 23%, with conversion to canal wall-down procedure in 67%. Factors identified as related to failure: cholesteatoma in the sinus tympani (33%), scutum erosion (29%), and large extension of disease (40%). Conclusion: The recurrence rate was significant, despite the high percentage of canal wall-down procedures. Factors for failure remain uncertain and CT scans presented limited value in the diagnosis and evaluation of cholesteatoma, especially postoperatively. In the absence of better diagnostic procedures, we recommend second look surgery to control cholesteatoma’s recurrence.

Effect of Duration of Irrigation with Sodium Hypochlorite in Clinical Protocol of MTAD on Removal of Smear Layer and Creating Dentinal Erosion.

Background and aims The aim of the present study was to compare 1.3% sodium hypochlorite (NaOCl) in MTAD (mixture of tetracycline isomer, acid, and detergent) for the removal of the smear layer and induction of canal erosion. Materials and methods 38 maxillary incisors were divided in three experimental groups of 10 and two positive and negative control groups of each 4 teeth, and prepared using rotary files. In test groups, 1.3% NaOCl was used for 5, 10 and 20 minutes during preparation followed by MTAD as the final rinse. In negative control group, 5.25% NaOCl was used for 10 minutes followed by 17% Ethylenediamine Tetra-Acetic Acid (EDTA) as the final rinse. In positive control group, dis-tilled water was used for 10 minutes during preparation and then as the final rinse. The samples were examined under scan-ning electron microscope, and the smear layer and dentinal erosion scores were recorded. Results Five and 10 min groups had significant differences with 20 min group (p < 0.05). In apical third, 5 and 10 min groups had also significant differences with 20 min (p < 0.05). In the coronal thirds, when the time of irrigation with 1.3% NaOCl increased from 5 min to 20 min, erosion also increased significantly. However, 5 and 10 min groups had no signifi-cant differences with negative control group. Conclusion The use of 1.3% sodium hypochlorite for 5 and 10 minutes in the MTAD protocol removes the smear layer in the coronal and middle thirds but does not induce erosion.

Design and analysis of a canal section for minimum water loss

Seepage and evaporation are the most serious forms of water loss in an irrigation canal network. Seepage loss depends on the channel geometry, while evaporation loss is proportional to the area of free surface. In this paper, a methodology to determine the optimal canal dimensions for a particular discharge is developed. The nonlinear water loss function, for the canal, which comprises seepage and evaporation loss, was derived. Two constraints (minimum permissible velocity as a limit for sedimentation and maximum permissible velocity as a limit for erosion of canal) have been taken into consideration in the canal design procedure. Using Lagrange’s method of undetermined multipliers, the optimal canal dimensions were obtained for minimum water loss. A computer program was developed to carry out design calculation for the optimal canal dimensions. The results are plotted in form of a set of design charts. The proposed charts facilitate easy design of the optimal canal dimensions guaranteeing minimum water loss. Water loss from the canal section can be estimated from these charts without going through the conventional and cumbersome trial and error method. Sensitivity analysis had been included to demonstrate the impact of important parameters.