New regression equations for mixed dentition space analysis in Nepalese mongoloids

Background

Mixed dentition space analysis methods using regression equations, namely, Moyers’ analysis and Tanaka-Johnston analysis are commonly used around the world. However, the applicability of these analyses among different racial groups have been questioned. The primary objective of this study was to assess the applicability of the Moyers’ and Tanaka-Johnston analyses among Nepalese Mongoloids and to develop regression equations for the same population if needed.

Methods

One hundred (50 males and 50 females) pre-treatment study models of the Nepalese Mongoloid patients undergoing orthodontic treatment were retrieved from the archives of the department of Orthodontics. The mesiodistal widths of mandibular incisors and widths of canines and premolars of all 4 quadrants were measured by a single investigator using a digital caliper to the nearest 0.01?mm. Predicted widths of canines and premolars were obtained using standard Moyers’ and Tanaka-Johnston analyses and then compared with the measured widths.

Results

The measured widths of canines and premolars were significantly different from the predicted widths obtained from Moyers’ and Tanaka-Johnston analyses. Strong and positive correlations were found between the sum of mesiodistal widths of mandibular incisors and the sum of mesiodistal widths of canines and premolars in males (0.73 for maxillary arch and 0.68 for mandibular arch) and females (0.64 for maxillary arch and 0.79 for mandibular arch).

Conclusions

The Moyers’ and Tanaka-Johnston analyses did not accurately predict the mesiodistal width of unerupted canines and premolars for Nepalese Mongoloid population. Hence, new regression equations have been developed for this population. However, validation studies should be conducted to confirm the applicability and accuracy of these equations.

     

Radiographic study of mandibular third molars: evaluation of the position and root anatomy in Brazilian population

Objectives

The root anatomy and position of mandibular third molars are important factors in assessing the level of difficulty of surgical removal procedures. In this light, this study aims to identify the most frequent position and the root anatomy of mandibular third molars.

Methods

The study sample comprised 1205 mandibular third molars from 710 panoramic radiographs evaluated. Regarding the position, all of them were based on Pell and Gregory’s and Winter’s classifications. The root anatomy was classified according to the type and number of roots, as well as the presence of laceration, fusion, or divergence. Gender and the quadrant were also considered. Following an interexaminer analysis, a statistical analysis was performed using the Kappa test.

Results

The results showed that the IA (40.3%) and mesioangular (53.8%) position was predominant in mandibular third molars. Regarding the anatomy, the most common were two roots (98.3%), of the conical simple type (88.9%), with absence of laceration (89.2%), divergence (84%), and fusion (80%).

Conclusion

The present study showed that the most prevalent mandibular third molar type in Brazilian patients was the IA and mesioangular position, with simple root anatomy. The result of this study can assist oral surgeons to better plan and assess the level of difficulty of surgical removal procedures.

     

Anesthetic Efficacy of 4 % Articaine During Extraction of the Mandibular Posterior Teeth by Using Inferior Alveolar Nerve Block and Buccal Infiltration Techniques

Introduction

The study was designed to evaluate the anesthetic efficacy of 4 % articaine with 1:100,000 epinephrine (A100) in infiltration and inferior alveolar nerve block (IANB) anesthetic techniques for the pain control during extraction of the mandibular posterior teeth.

Methods

This prospective randomized single-blind clinical trial included 100 patients needing extraction of at least two mandibular molars. Patients received either infiltration in the buccal vestibule opposite to the first molar supplemented with lingual infiltration or standard IANB with A100. For assessment of depth of anesthesia obtained by the two anaethetic techniques, presence or absence of pain during the extraction were rated using the visual analog scale.

Results

Fifty patients received infiltration anesthesia and fifty patients were anesthetized by IANB. The success rate of pain-free extraction after buccal infiltration was 94 %, whereas by using IANB with the same anesthetic it was 92 %. No statistical differences were detected in the success rates between the two anesthetic techniques (P = 0.15).

Conclusions

Buccal Infiltration can be considered a good option during extraction of the mandibular molar and premolar teeth of course, with supplemental lingual anesthesia.

     

A morphometric analysis of the mandibular canal by cone beam computed tomography and its relevance to the sagittal split ramus osteotomy

Purpose

The aim of the present study was to morphometrically analyze the mandibular canal through the mandibular ramus by cone beam computed tomography (CBCT) and to relate the findings to performing sagittal split ramus osteotomy.

Methods

CBCT of 200 patients were analyzed. Five parameters were measured at the axial scan, from the mandibular foramen to 21 mm below it (3-mm intervals). The canal was classified according to the position within the bone marrow space. Variations were evaluated according to age, sex, side, and number of mandibular teeth.

Results/conclusions

The following measurements increased gradually towards the most inferior level of measurement: the total thickness of the mandibular ramus through the center of the mandibular canal, the width of the bone marrow space (both buccal and lingual), and the narrowest width from the mandibular canal inner cortical to the mandibular ramus external cortical. The inner diameter of the mandibular canal slightly decreased to the same direction. Concerning the mandibular canal position within the bone marrow space, the percentage of the separate type increased towards the most inferior level of measurement, and the contact and fusion types decreased. Age, number of teeth, and sex had no significant influence on the total thickness of the mandibular ramus and on the narrowest width from the mandibular canal inner cortical to the mandibular ramus external cortical.

     

Role of Panoramic Imaging and Cone Beam CT for Assessment of Inferior Alveolar Nerve Exposure and Subsequent Paresthesia Following Removal of Impacted Mandibular Third Molar

Objectives

Pre-operative radiographic evaluation of impacted mandibular third molar and inferior alveolar canal (IAC) is important in preventing a possible nerve exposure and damage during surgical removal. The present study analysed the relation of the mandibular third molar with inferior alveolar canal using panoramic radiography (PAN) and cone beam CT (CBCT) and evaluated the radiographic features suggestive of IAN exposure and post-operative paresthesia.

Materials and Methods

PAN and CBCT findings of 53 impacted mandibular third molars having a close relation with IAC undergoing extraction were analysed. Further, all cases were evaluated for any sensory loss in relation to IAN 1 week post-operatively.

Results

The most common PAN feature was combination of darkening of roots (DR) and interruption of white line (IWL), seen in 35.86% (19) cases. The most common CBCT feature was thinning of lingual cortex in 81.14% (43) cases. The most common location of IAC in CBCT was inferior in 47.16% (25) cases, followed by buccal 26.41% (14). On comparison of PAN and CBCT findings, DR and IWL both exclusively 92.86% (13); 80% (12) cases and in combination 75% (15) were most commonly associated with thinning of lingual cortex. IAN exposure was seen in 7.55% (4) cases, and 3.77% (2) cases reported with paresthesia. Absence of corticalisation and IWL was associated with all cases of nerve exposure, inter-radicular location of IAC seen in three out of the four cases. Cases with paresthesia had DR and deflection of roots (DEFR) with thinning of lingual cortex by roots.

Conclusion

DR with DEFR or IWL in PAN as combination and inter-radicular location of IAC with thinning of lingual cortex by root tips in CBCT are highly predictive of nerve exposure and subsequent paresthesia.

     

Surgical treatment of painful inferior alveolar nerve injuries following endodontic treatment: a consecutive case series of seven patients

Purpose

Injuries of the inferior alveolar nerve (IAN) related to endodontic treatment are being increasingly reported. However, consensus on the preferred intervention and the timing of and indications for surgical treatment is lacking. Here, we describe our experience with painful IAN injuries arising from endodontic treatment and requiring prompt microsurgical treatment.

Methods

Seven consecutive patients with painful IAN injuries were referred to the Maxillofacial Surgery Unit of San Paolo Hospital in Milan. All patients had undergone root canals endodontic treatment in the mandibular molar or premolar between 2007 and 2014. The time elapsed between injury and referral for surgical treatment ranged from 10 days to 20 months. Each patient was treated by one of several different microsurgical procedures, described herein.

Results

Overall, neurosensory status and IAN-related pain improved in all seven patients. The best results were obtained by IAN replacement with a sural nerve graft. However, complete sensory recovery was not achieved in any of the patients.

Conclusions

Although our sample includes only seven patients, early surgical treatment with an interpositional sural nerve graft seems to allow neurosensory recovery. Less satisfactory results are achieved in patients with IAN injuries of > 12 months duration.

     

Mandibular war injuries caused by bullets and shell fragments: a comparative study

Purpose

Is to compare the patterns, severity, and management of the high- and low-velocity mandibular war injuries managed at Al Shaheed Gazi Al-Hariri Hospital in Baghdad Medical City, Iraq, during a 2-year period.

Methods

Forty-one patients with a history of mandibular war injuries treated by our maxillofacial team were reviewed during a period of 2 years (2015–2017). All patients were treated in the Maxillofacial Unit of the Hospital of Specialized Surgeries in Baghdad Medical City.

Results

A 2-year retrospective study evaluated 41 patients with mandibular war injuries with a total of 94 fractures (comminution represents 79.06% of the bullet injuries, while it is only 62.74% with IED injuries). Management of these injuries was varied according to the severity of the injuries and resources available. Close reduction was used in 72.72% of the linear fracture cases, whereas open technique was used in 56.6% of the comminuted fractures.

Conclusions

Bullet injuries were associated with a higher number of mandibular comminuted fractures, in addition to more extensive bone loss. While shell injuries of IED (improvised explosive devices), on the other hand, were associated with higher infection rate and more postoperative complication.

     

Endodontic Outcomes in Mandibular Second Premolars with Complex Apical Branching

Introduction

Mandibular premolars that have rare and complex anatomies may have the highest failure rate in nonsurgical endodontic treatment. Awareness of rare and complex anatomies of mandibular second premolars would aid in better outcomes of the treatment. This study aimed to evaluate the success of nonsurgical root canal treatment of mandibular second premolar teeth with complex apical branching.

A Self-Retaining Lingual Flap Guarding Device During Surgical Removal of Impacted Mandibular Third Molar

Introduction

Lingual nerve damage is one of the common complications following mandibular third molar surgery. On considering the impact of lingual nerve damage on the patient’s quality of life, it is necessary to exercise caution to minimize its occurrence.

Material and methods

Although many lingual retractors are available, in this article we describe an indigenously designed lingual retractor for use in mandibular third molar surgery.

Conclusion

The indigenous lingual retractor described in this article provides advantages like clear access and excellent retention unlike conventional retractors.

     

Superolateral Dislocation of Bilateral Intact Mandibular Condyles: A Rare Case Series

Background and Purpose

The dislocation of mandibular condyle is a clinical condition in which the head of condyle has been displaced out of the glenoid fossa. Complete dislocation of the mandibular condyle can occur in anterior, posterior, lateral and superior direction. Among these dislocations, bilateral superolateral dislocation of mandibular condyles is quite rare and often misdiagnosed. Because of its rare occurrence and unusual clinical course, the best treatment is debatable.

Patients and Method

We present the first case series of true bilateral superolateral dislocation of intact mandibular condyles (Type 2B) without fracturing the Zygomatic arch, associated with symphysis fracture.

Conclusion

This article intends to provide information regarding the possible biomechanics and management of bilateral superolateral dislocation of mandibular condyles associated with symphysis fracture.

     

Intermittent or continuous ultrasonically activated irrigation: micro-computed tomographic evaluation of root canal system cleaning

Objectives

The aim of this study was to evaluate the efficacy of two passive ultrasonic irrigation (PUI) methods and conventional manual irrigation (CMI) in root canal system (RCS) cleaning.

Materials and methods

Artificial single-rooted teeth were used. Four lateral canals were made 2 and 7 mm short from the apex. Root canals were filled with a contrast solution. The specimens were divided into four groups (n = 8): PUI1—intermittent flushing; PUI2—continuous flushing; CMI1—at 1 mm; and CMI2—at 3 mm. Micro-computed tomographic images were obtained. New images were taken after the irrigation protocols enabling the evaluation of the contrast solution volume (in mm³) within RCS (main and lateral root canals) in comparison to the initial analysis. The comparison among groups was performed using ANOVA and Tukey’s tests with 5 % significance level.

Results

There was no difference among PUI1, PUI2, and CMI1 regarding the contrast solution removal from RCS (p > 0.05). These methods demonstrated greater cleaning than CMI2. At the apical third, CMI2 showed lower cleaning capacity when compared to the other methods (p < 0.05).

Conclusions

PUI with intermittent or continuous flushing and CMI with the needle placed 1 mm from the working length were efficient in cleaning the main and lateral root canals.

Clinical relevance

Root canal irrigation plays an important role in cleaning and disinfection of the RCS. Effective apical irrigation is an important procedure during root canal treatment. PUI and CMI (at 1 mm short) were effective in cleaning of the main and simulated lateral root canals.

     

Factors affecting observer agreement in morphological evaluation of mandibular cortical bone on panoramic radiographs

Objectives

To assess intra- and inter-observer agreement in the morphological evaluation of mandibular cortical bone on panoramic radiographs, to examine factors affecting the diagnosis, and to determine causes of diagnostic discrepancy.

Methods

Three experienced observers evaluated mandibular cortical shape on panoramic radiographs of 228 females, and divided the images into three classes. The intra- and inter-observer agreements were calculated. The effect of mandibular cortical width on shape classification was examined. Causes of diagnostic discrepancy were investigated.

Results

Overall intra- and inter-observer kappa values in diagnosing mandibular cortical shape were 0.58–0.76 and 0.62–0.69, respectively. The kappa values in diagnosing Class 2 were low. In radiographs diagnosed as Class 2 and Class 3, the ranges of mandibular cortical width overlapped. Discrepancies in diagnosis were caused by slight resorption at the endosteal margin of the cortical bone, endosteal cortical residues near the thinned smooth cortex, and superimposition of the hyoid bone over the mandible.

Conclusions

Inter-observer agreement in evaluating mandibular cortical shape was moderate to substantial. Diagnostic discrepancies were mainly caused by differences in evaluation of the endosteum near the cortical bone.

     

Apical pressure created during irrigation with the GentleWave™ system compared to conventional syringe irrigation

Objectives

The purpose of this study is to compare pressures at the apical foramen created by conventional syringe irrigation and the GentleWave? System, which releases high-velocity degassed irrigants to the pulp chamber and uses broad-spectrum sound energy for cleaning.

Materials and methods

The apical pressure generated during irrigation was measured for palatal and distobuccal root canals of four extracted maxillary molars after no instrumentation, minimal instrumentation to a size #15/.04, instrumentation to a size #40/.04 taper, and after perforating the apical foramen to size #40. The root canals opened into an air-tight custom fixture coupled to a piezoresistive pressure transducer. Apical pressures were measured for the GentleWave? System and syringe-needle irrigation at different irrigant flow rates, with the needle tip at 1 and 3 mm from the apical foramen using 30-gauge (G) open-ended or side-vented safety tip needles.

Results

The GentleWave? System generated negative apical pressures (P < 0.001 compared with syringe irrigation); the mean pressures were between ?13.07 and ?17.19 mmHg. The 30 G needles could not reach the 1 and 3 mm from the working length in uninstrumented and 1 mm in minimally instrumented canals. The mean positive pressures between 6.46 and 110.34 mmHg were measured with needle irrigation depending on the flow rate, needle insertion depth, and size of the root canal.

Conclusions

The GentleWave? System creates negative pressure at the apical foramen during root canal cleaning irrespective of the size of canal instrumentation. Positive apical pressures were measured for syringe irrigation.

Clinical relevance

Negative pressure during irrigation contributes to improved safety as compared to high-positive pressure.

     

Osteoporotic mandibular changes caused by type 2 diabetes mellitus: a comparative study by cone beam computed tomography imaging

Objectives

Studies on bone mineral density and fracture risk in diabetic patients have attracted interest in the last few years. This study was aimed at comparing mandibular osteoporotic changes assessed by qualitative and quantitative radiographic methods in the mandibles of type 2 diabetes mellitus patients with those of non-diabetic subjects using cone beam computed tomographic images.

Methods

This quantitative and qualitative study of mandibular bone in diabetic patients included 23 type 2 diabetes mellitus patients and an equal number of healthy subjects. Radiomorphometric measurements were performed for each subject using cone beam computed tomography images. Changes in cortical bone thickness were determined by measuring bone area. Fractal dimension analysis was applied to evaluate the trabecular structure of the bone.

Results

No statistically significant difference could be established between the type 2 diabetes mellitus group and the control group in regard to either radiomorphometric measurements or fractal dimension analysis. Quantitative assessment of mandibular bone indicated a thinning of the cortical bone, with a statistically significant difference between the type 2 diabetes mellitus patients and the healthy controls.

Conclusions

Bone condition related to diabetes involves complex pathophysiological mechanisms; thus, radiographic imaging parameters may be useful as an adjunct to clinical parameters.

     

Evaluation of root canal morphology of mandibular premolars in a Saudi population using cone beam computed tomography: A retrospective study

Objective

To investigate the root canal morphology of mandibular first and second premolars using Cone-Beam Computed Tomography (CBCT) in a Saudi population.

Case–control study of mandibular canal branching and tooth-related inflammatory lesions

Objectives

Morphological variations of mandibular canals increase the risk of neurovascular damage and bleeding during surgical procedures by decreasing the predictability of the inferior alveolar neurovascular bundle location. To improve the predictability with such variations, the present study aimed to verify the possibility of a relationship between mandibular canal branches (MCBs) and tooth-related inflammatory lesions, using trough cone-beam computed tomography (CBCT) examinations.

Methods

The sample comprised 150 age and sex-matched examinations (50 cases and 100 controls) from two databases. The CBCT examinations were grouped by the presence of MCBs starting in the mandibular body regions as the outcome variable. Tooth-related inflammatory lesions and measurements of gray levels in the posterior region of the alveolar ridge were assessed in both groups. A multiple logistic regression analysis was applied to verify the relationships between MCBs and independent variables (p?<?0.05).

Results

Occurrence of tooth-related inflammatory lesions increased the risk of MCBs in the mandibular body regions (p?<?0.001; OR 11.640; 95% CI 4.327–31.311). High-contrast images had a weaker association with MCBs (p?=?0.002; OR 1.002; 95% CI 1.002–1.003). The most frequent tooth-related inflammatory lesions in both groups were endodontic (34 lesions; 45.94% of the total lesions). Most of the tooth-related inflammatory lesions related to MCBs were endodontic (20 cases) and combined endodontic and periodontal inflammation (20 cases).

Conclusions

An association was observed between MCBs in the mandibular body regions and tooth-related inflammatory lesions. Inflammatory lesions of endodontic origin are most often associated with MCBs.

     

Double unilateral,bilateral, and multiple mandibular fractures: an observational study

Purpose

Double and multiple mandibular fractures are associated to high morbidity and functional damage. This study aimed to evaluate the characteristics and outcomes of double unilateral, bilateral, and multiple mandibular fractures.

Methods

A 7-year observational retrospective analysis was performed, and the injury-related data were collected from the medical records. Statistical analysis was performed using Fisher’s exact test (p?<?0.05).

Results

In this period, 283 patients showed mandibular fractures. Of them, 83 (29.7%) had double or multiple mandibular fractures and were included in the study. Double bilateral fractures were more prevalent than multiple or double unilateral. Multiple fractures presented significant association with the combination of load-bearing and load-sharing fixation protocols. Most cases (94.0%) applied at least one type of internal fixation system. However, there was a positive association between condylar fractures and non-surgical treatment (p?<?0.01). Moreover, mandibular body fractures were associated with load-bearing fixation (p?<?0.01). In 56 cases, no complications were observed (67.5%). Complications were divided into treatment failure (10.8%) and transitory or minor complications (21.7%). There was no statistical association between complications and fracture pattern, fracture-tooth relation, and treatment modality.

Conclusion

Double and multiple mandibular fractures represented almost one third of all mandibular fractures, and regardless to treatment protocol, there was no difference about complications. Moreover, although a considerable complication rate was found, most of them were minor or transitory.

     

Evaluation of retromolar canals on cone beam computerized tomography scans and digital panoramic radiographs

Purpose

The purpose of this study was to carry out morphologic and topographic analyses of retromolar canals on cone beam computerized tomography (CBCT) scans, comparing findings to others obtained from the corresponding digital panoramic radiographs.

Methods

Sixty-one CBCT scans were analysed digitally, as well as their corresponding digital panoramic radiographs. The prevalence and distribution of these canals, foramen diameters, and intraosseous communications were also evaluated.

Results

On CBCT scans, we found that 24.6% of individuals had at least one retromolar canal. The mean foramen diameter was slightly higher than 1 mm and we could not determine the intraosseous anatomical connections in most cases. The morphology and topography of the retromolar canals were not affected by gender and antimere. In addition, only 22.2% of all tomographically identified canals could be confirmed on digital panoramic radiographs (26.7% of such patients). Regarding all sample, 6.6% of individuals showed retromolar canals on digital panoramic radiographs.

Conclusion

We may consider that these structures are clinically relevant findings and, due to the low accuracy of the panoramic radiographs, high-quality tomographic exams should always be asked for presurgical treatment planning.