Assessment of the position and level of mental nerve for placement of implants using cone-beam computed tomography & panoramic radiograph in the Saudi population

Background and objectiveIn surgical dentistry, shape, location, position, and extent of the anterior loop of mental foramen plays a deliberately imperative landmark during an osteotomy procedure. To evade any neurological disturbance during implant surgery radiological assessment is compulsory. Therefore, the aim of the study was to assess the position and level of mental nerve for placement of implants using Cone-beam computed tomography & Panoramic radiography in the Saudi population.Materials and methodsA total of 150 CBCT and Panoramic radiographs were taken from the patients who visited the Department of Oral Medicine and Radiology. The data collection was done by using the same radiographic pieces of equipment for both CBCT and Panoramic radiographs. CBCT images taken from Kodak 9000 3D, Carestream Health, Inc., New York, USA, and Panoramic Radiographs taken from Panoramic Planmeca ProMax, Helsinki, Finland (Vujanovic-Eskenazi et al., 2015). The Chi-square test student test was used for statistical analysis.ResultsThe most frequent shape and location of mental foramen in both CBCT and Panoramic radiographs were oval and in between the first and second premolar, both in CBCT & PR views. The visibility of mental loop on CBCT & PR view showed that; visibility of mental loop in CBCT was higher with 42(56%) as compared with PR view 26(34.66%) with statistically significant p-value 0.014. The mean length of the mental loop on CBCT was statistically significant (p = 0.001). But the mean distance from the lower point of the mental foramen to the lower border of the mandible was not statistically significant.ConclusionBased on the results of the present study; the visibility of the mental loop and its extension is more in CBCT as compared with PR views. Therefore, we recommended CBCT, during of implant surgery.     

X线曲面体层摄影下颌管显现情况的临床研究

目的 观察X线曲面体层摄影下颌神经管的显现率及冠根向直径，为种植手术提供指导。方法 选择种植义齿及牙周病曲面体层摄影片200例，反复测量曲面体层摄影片下颌神经管及孔的显现情况和冠根向直径并记录部位。结果 大部分下颌管可经曲面体层摄影显现，显现率和冠根向直径从后向前降低，双侧显现率经配对t检验无显著性差异（P＞0.05）。结论 X线曲面体层摄影下颌管及麂孔的显现率较高，适用于大部分种植义齿手术设计，少部分下颌管显现不清，应拍摄螺旋CT以明显下颌管的确切部位和走行，以减少对下牙槽神经的损伤的发生率。     

Anterior loop of the mental nerve in Saudi sample in Riyadh,KSA. A cone beam computerized tomography study

BackgroundThe portion of inferior alveolar nerve (IAN) existent anterior to the mental foramen, before parting the canal, is referred to as the anterior loop (AL) of the IAN. The presence of AL is important when placing the implant interforaminal area of the mandible. These anatomical discrepancies can be assessed by cone-beam CT (CBCT), for evaluating its position and exact location. The AL is classified into Types I, II and III. In Type I, Y-shaped anatomy; in Type II, anatomy is T-shaped; and in Type III, Y-shaped anatomy is seen, and the incisive branch is thicker as compared to the main branch.AimIn this study, we aim to analyse the prevalence of different types of AL of the IAN in Saudi sample population.Materials and MethodsThe present study is a retrospective analysis of 149 (86 female & 63 male) CBCT images of patients records from 2018 June to 2018 September in the department of implant dentistry, KSMC, Riyadh. The age range of the patients who participated in the study was 30–60 years. The mean age of female participants is 42.5 ± 5.8, for the male participants is 48.6 ± 11.4 years respectively.ResultsThe most frequent type of AL of mental nerve noticed on the right side was of type I (59.1%), followed by type II (27.5%) and type III (13.4%). The most frequent type of AL of mental nerve noticed on the left side was type I (61.7%), followed by type II (26.8%) and type III (11.4%).ConclusionThe results of the study encourage the usage of CBCT for planning implant treatment. We also suggest that it is obligatory for professionals to categorise the presence of AL and to measure them appropriately when planning for the procedures in the interforaminal region.     

Patterns of emergence of the human mental nerve

This study investigated the path of emergence of the mental nerve in a number of human population groups. Skeletal material comprised 117 Negro skulls (53 males), 114 caucasoid skulls (62 males) and 100 pre-contact Maori skulls (70 males). In each case, the path of emergence was classified into posterior, anterior, right-angled or multiple. Those cases with severely resorbed alveolar ridges that made classification difficult were excluded from the study. Additionally, 56 cadaveric mandibles were examined, in which an osteotomy of 1cm was made on either side of the mental foramen to expose the nerve. The most common pattern of emergence in caucasoids and Maoris was a posterior direction (86.7% of caucasoid males, 90.2% of caucasoid females; 85.5% of Maori males, 93.1% of Maori females). In Negroes the most common pattern was a right-angled path of emergence (45.8% of males, 45.0% of females), with this difference between population groups being statistically significant (Pearson's chi(2): males=23.4, females=45-97; P<0.01). Multiple foramina were rare, with the highest incidence being in Maori and Negro males. Cadaveric data supported the findings of the skeletal investigation, with the dominant emergence recorded as posteriorly directed (80.7% of males, 86.6% of females). It was concluded that while the traditionally accepted ontogenetic explanation for the inclination of the mental nerve might be applicable to caucasoids and Maoris, it fails to explain the observed right-angled emergence pattern in Negroes. Hence, the nerve's emergence might be genetically, rather than functionally, determined. The study did not show a measurable anterior loop in the emergence of the mental nerve that would have any significant impact on treatment planning for implants in the anterior mandible.     

Determination of the position of mental foramen and frequency of anterior loop in Saudi population. A retrospective CBCT study

Objectives

To determine the position of mental foramen (MF) and frequency of anterior loop (AL) using dental cone beam computed tomography (CBCT).

Assessment of 3,031 panoramic radiographs in an urban Turkish population: a community survey

Objectives  The present study was performed to assess the total and average numbers of radiopaque restorations, missing or impacted teeth, root-canal fillings, crown-fixed partial dentures, and implants in 3,031 radiographs of patients with respect to age and gender in an urban Turkish population. Methods  In total, 3,031 panoramic radiographs were examined. The study included all patients examined at the Faculty of Dentistry, Baskent University, Turkey. The total and average numbers of radiopaque restorations, missed or impacted teeth, root-canal fillings, crown-fixed partial dentures, and implants were assessed. The patients were categorized into two groups with respect to age and gender. The patients were further divided into four subgroups with respect to age (14–30, 31–45, 46–60, and >60 years), each of which was evaluated separately. Results  Molar teeth were the most frequently restored or missing teeth. The number of posterior restorations increased with age up to 45 but seemed to decrease in the 46–60 and over 60-year-old subgroups. However, the number of missing teeth, and thus fixed partial dentures, and root-canal treatments increased in these subgroups. The number of implants increased with age. Although women had more restored teeth, they also had fewer missing teeth. The total number of restorations on the right side of the mouth was higher than that on the left side. Conclusion  This study revealed the oral condition of an urban Turkish population. Future multicenter studies conducted periodically will help evaluate the parameters mentioned above regarding the oral-health status of the Turkish population and quality of the dental-care system in Turkey.     

锥形束计算机体层摄影术观察下牙槽神经管形态及其临床意义

目的 应用锥形束计算机体层摄影术（CBCT）观测并分析下牙槽神经管在下颌骨内的走行特点,探讨其分布规律,为临床手术提供解剖学依据.方法 采用单纯随机抽样法选取具备下颌后部CBCT 扫描数据的患者60 例,应用CBCT 自带的KaVo eXam Vision 软件测量颏孔区、前磨牙区、磨牙区下牙槽神经管与牙槽嵴顶、下颌骨颊舌侧骨板及下缘的平均距离,对各组测量项目进行成组t 检验比较,并观察其走行特点.结果 下牙槽神经管距下颌下缘小于距牙槽嵴顶的距离,在第二磨牙区距离下颌骨下缘最近;颏孔区至第一磨牙区间,下牙槽神经管距颊侧骨板距离小于距舌侧骨板距离,自第二磨牙后,下牙槽神经管距颊侧骨板距离则大于距舌侧骨板距离;性别及左、右侧下牙槽神经管距离差异无统计学意义（t＝2.437,P ＞ 0.05）.结论 CBCT 扫描有利于更好了解下牙槽神经管的走行及结构特异性,对牙槽外科及种植外科手术方案的制定具有一定临床指导意义.     

CBCT观察颏孔与下颌第二前磨牙根尖位置关系

目的：测量下牙槽神经管及颏孔与下颌第二前磨牙根尖位置关系,分析其分布规律,以期为显微根尖手术提供解剖学依据。方法：选取83例双侧锥形束CT（CBCT）图像,分析颏孔开口位置分布规律,并测量下牙槽神经管及颏孔与下颌第二前磨牙根尖位置关系。结果：颏孔到牙槽嵴顶、下颌骨下缘的平均距离分别为（12．96±1．91）mm、（13．24±1．57）mm;在曲面体层片上,下颌第二前磨牙根尖到颏孔的最短距离平均（2．64±1．61）mm;若颏孔位于下颌第一、二前磨牙之间或第一前磨牙下方时,下颌第二前磨牙根尖到下牙槽神经管的平均距离（5．35±2．05）mm。男女性别分组对比在颏孔下缘距下颌骨下缘、下颌第二前磨牙根尖到下牙槽神经管距离的平均值差异均有显著性（P＜0．05）。结论：下颌第二前磨牙根尖与颏孔及下牙槽神经管关系密切,在进行下颌第二前磨牙的显微根尖手术过程中,应当给予充分重视。     

Demonstration of the accessory mental foramen using rotational panoramic radiography compared with cone-beam computed tomography

Objective: Rotational panoramic radiography is routinely used in dental practice. It has not been clarified, however, whether an accessory mental foramen can be demonstrated using this technique. The visibility of accessory mental foramina on rotational panoramic radiographs was compared with those on para‐panoramic images reconstructed from cone‐beam computed tomographic (CBCT) images. Materials and methods: A total of 365 patients (130 males and 235 females) were retrospectively analyzed. Para‐panoramic images were reconstructed from CBCT images with the accessory mental foramen/foramina using three‐dimensional visualization and measurement software, and then the accessory mental foramen on rotational panoramic images was compared with that on para‐panoramic images. Results: A total of 37 accessory mental foramina were observed in 28 patients on CBCT images. The rate of being able to visualize the accessory mental foramen or bony canal between the point of bifurcation from the mandibular canal and the accessory mental foramen on rotational panoramic radiographs was 48.6% (18 of 37 accessory mental foramina). Conclusion: Approximately half of the accessory mental foramina‐positive CBCT images demonstrated the accessory mental foramen, or bony canal between the point of bifurcation from the mandibular canal and accessory mental foramen on rotational panoramic radiographs. To cite this article:
Naitoh M, Yoshida K, Nakahara K, Gotoh K, Ariji E. Demonstration of accessory mental foramen using rotational panoramic radiography compared with cone‐beam computed tomography.
Clin. Oral Impl. Res. xx , 2011; 000–000.     

Assessment of the anterior loop of the inferior alveolar nerve using reformatted computed tomography: a retrospective study

The anterior loop of the inferior alveolar nerve (IAN) is an important landmark in the anterior mandible that must be considered during the placement of dental implants. We measured the length and prevalence of loops of the IAN in 188 consecutive, dentate patients using reformatted computed tomography (CT). A total of 158/188 (84%) had at least one anterior loop; 111/188 (59%) had bilateral loops. The mean (SD) length of the loops in the third quadrant was 1.4 (0.7) mm; 95% CI 1.3 to 1.6; (range 0.3 – 4.0 mm). The mean (SD) length of the loops in the fourth quadrant was 1.5 (0.9) mm; 95% CI 1.4 to 1.6; range 0.3 – 5.5 mm. In total 42/188 (22%) had loops that were longer than 2 mm in quadrants three and four. CT images that have been reformatted with specialised software may be useful to identify loops in the IAN, particularly when recent cone-beam CT images are not freely available. The prevalence of these loops is high while their length varies, which makes meticulous assessment necessary before the placement of implants.     

Radiographic assessment of the mandibular retromolar canal using cone-beam computed tomography

Abstract

Objective. The ‘retromolar’ nerve is a collateral branch of the inferior alveolar nerve. Cone-beam computed tomography (CBCT) provides higher resolution images. This CBCT study reports the frequency of the retromolar nerve. Materials and methods. From 2007–2010 the CBCT study of 233 hemi-mandibles have been examined. The CBCT study was obtained from an investigation of the posterior mandibular region in 187 patients suffering from different pathologies and it was aimed at detecting in patients the presence of a retromolar canal and foramen. Results. Thirty-four retromolar canals with a foramen were detected on 233 CBCT (14.6%) in 30 out of 187 patients (16%). In the 46 patients who underwent CBCT bilaterally, the retromolar canal was found in nine subjects (19.6%) and was present bilaterally in four subjects, for an incidence of 8.7%. Conclusions. The results suggest that the radiological frequency of the retromolar nerve is notable, with a possible relevance in the surgical approach of the mandibular retromolar area. The presence of a retromolar canal, well detected with CBCT, may warn clinicians about the possibility of inadequate pre-surgical anaesthesia, local intra-operative bleeding and post-operative alterations of the sensation in the third molar area.     

Detection and characterization of the accessory mental foramen using cone-beam computed tomography

Objective: This study aimed to investigate the frequency and characteristics of accessory mental foramina (AMFs) and their bony canals in a selected Chinese population using cone-beam computed tomography (CBCT).

Materials and methods: Reconstructed CBCT images of the mandible in 784 Chinese patients (305 males and 479 females) were retrospectively analysed to identify the AMF. The presence, dimension and location of the AMF as well as the origin and course of the associated bony canal were evaluated and classified. Variations in these characteristics were analysed according to gender, side and age.

Results: A total of 66 AMFs were found in 57 (7.3%) of the 784 patients. The frequency of AMFs was significantly influenced by gender and side of the mandible (p?Conclusions: This study presents a considerable frequency of AMFs in a Chinese population. The high-position AMF and the associated bony canal coursing in the oblique upward direction appear frequently. Thus, clinicians should be alert to the presence of the AMF to avoid neurovascular complications especially when dental procedures require periosteum detachment and implant insertion in the mental region.     

Conservative surgical and microsurgical techniques for the management of dental implants that impinge on the inferior alveolar nerve

Loss of sensation in the lip after insertion of an implant is annoying. The aim of this paper was to describe two techniques for management of osseointegrated dental implants that impinge on the mandibular nerve, the purpose of which is to improve sensation without unscrewing the dental implant.     

Pre-operative assessment of relationship between inferior dental nerve canal and mandibular impacted third molar in Saudi population

ObjectiveTo study the correlation between the position of the inferior dental (ID) nerve canal and the angulation of impacted mandibular third molars using dental cone beam computed tomography (CBCT).Materials and methodsThe study considered 100 impactions in 85 patients (60 males, 25 females), for whom an initial panoramic radiographic assessment had revealed that the ID canal and the lower 3rd molar were in close proximity. A CBCT scan of each patient was carried out to assess how the ID nerve canal position influenced the class and position of impaction, angulation of impaction, and bone contact.ResultsClass I position B impactions were found in the majority of cases, where the position of the ID canal was approximate to the lingual plate and inferior to the 3rd molar (85.7%). The results were statistically significant (p = 0.001). 96% of the ID canals showed bone contact. Of these, 77.1% of ID canals exhibited lingual bone contact, inferior to impaction. The results were statistically significant (p = 0.001). Horizontally angulated impactions were most common in the mandible, and significantly associated with lingual and inferior positioning of the ID canal (76.2%).ConclusionsOur sample population most commonly exhibited horizontally angulated class I position B impactions of the mandible. The position of the ID canal significantly influenced the type of impaction and bone contact.     

Evaluation of accessory mental foramen and accessory infraorbital foramen with cone-beam computed tomography in Turkish population

It was aimed to evaluate the frequency of accessory mental foramen (AMF) and accessory infraorbital foramen (AIOF) and analyse the correlation between these two foramina using cone-beam computed tomography (CBCT). The retrospective study reviewed the CBCT images of 1020 patients. The rates of AMF and AIOF were evaluated according to sex and age distributions. Correlations between the localizations of AMF and AIOF in the right and left jaws and the correlations between the occurrences of these foramina were evaluated. In the CBCT images of the 1020 patients, AMFs were detected in 48 patients, among which 14 were in the right half jaw, and 34 were in the left half jaw. AIOFs were detected in 143 patients, among which 65 were in the right half jaw, and 78 were in the left half jaw. Recognising and detecting AMF and AIOF with CBCT is important in terms of preventing complications that may occur in surgical procedures.     

Risk assessment of inferior alveolar nerve injury for immediate implant placement in the posterior mandible: A virtual implant placement study

Objectives

To investigate the prevalence and morphological parameters of lingual concavity, and whether these factors are related to a higher risk of inferior alveolar nerve (IAN) injury when performing an immediate implant surgery in posterior mandible region.

Methods

The CBCT images from 237 subjects (1008 teeth) were analysed the shape of the mandibles (C, P, U type), dimensional parameters of lingual concavity (angle, height, depth), and its relation to inferior alveolar canal (IAC) (A, B, C zone), RAC (distance from root apex to IAC) and probability of IAN injury. Multiple logistic regression modelling to determine the odds ratio of variables that made an important contribution to the probability of IAN injury and to adjust for confounding variables.

Results

The U type ridge (46.7%) and the most concave point located at C zone (48.8%) are most prevalent in this region. The mandibular second molar presents highest risk for IAN injury than other tooth type (p < 0.001), which were 3.82 times to occur IAN injury than the mandibular second premolar. The concave point located at A zone and B zone were 7.82 and 3.52 times than C zone to have IAN damage, respectively. The probability of IAN injury will reduce 26% for every 1 mm increase in RAC (p < 0.001).

Conclusions

The tooth type, morphological features of lingual concavities, and RAC are associated with risks of IAN injury during immediate implant placement.

Clinical significance

Pre-surgical mapping of the IAC and identification of its proximity relative to the lingual concavity in the posterior mandible regions may avoid unpleasant complications, specifically when performing immediate implant procedures.     

Maxillary molar root protrusion into the maxillary sinus: a comparison of cone beam computed tomography and panoramic findings

This study aimed to examine the prevalence of molar roots protruding into the maxillary sinus and to determine the panoramic radiographic signs as correlated with cone beam computed tomography (CBCT). CBCT images of 354 roots were assessed and classified into three types, according to the relationship between the root and maxillary sinus. The prevalence of root protrusion into the maxillary sinus was calculated then the panoramic images assessed. After excluding some unidentified roots on the panoramic images, 200 were investigated for panoramic signs, including (i) projection of the root apex into the sinus cavity, (ii) interruption of the maxillary sinus floor’s cortex, (iii) absence of periodontal ligament space, (iv) darkening of the involved root region, and (v) upward curving of the sinus floor. The respective correlation between the panoramic signs and CBCT types was assessed. Forty-six percent of roots showed protrusion into the sinus with the palatal root of the first molar having the greatest prevalence (33/200 roots). The panoramic signs ‘projection of the root apex in the sinus cavity’ and ‘darkening of the involved root apical region’ both strongly indicated root protrusion into the maxillary sinus (P < 0.05).     

Precise computer-based localization of the mental foramen on panoramic radiographs in a Kurdish population

Objectives  To develop and characterize a computer-based application to locate the position of the mental foramen (MF) on orthopantomograms of both dentulous and edentulous patients. Methods  Panoramic radiographs were analyzed using the computer programs Photoshop and AutoCAD to locate the MF in the horizontal and vertical planes in 110 dentulous patients and in the superior/inferior planes of 50 completely edentulous patients. Results  In the dentulous population (n = 110), the anteroposterior position of the MF was primarily defined by being in line with either the longitudinal axis of the lower second premolar (n = 60, 55%) or the longitudinal axis of a point between the first and second premolars (n = 39, 35.9%). The anteroposterior position of the MF was asymmetrical in 17.3% of the patients (10.3% of men and 25% of women). In the vertical plane, the MF was located slightly below the midpoint between the inferior border of the mandible and the alveolar bone crest. No significant differences related to side (P > 0.05) was detected. Conclusions  Our convenient, computer-based application facilitates the rapid pin-pointing of the MF on panoramic radiographs. In the present study, the MF was located directly below the mandibular second premolar in the majority of Kurdish patients. These results and techniques may be useful when any mandibular surgery is planned.     

种植体参照法在曲面体层片后牙区测量中的应用及误差分析

目的：提出一种以种植体为参照用于曲面体层片后牙区局部测量的方法,并对其误差进行分析。方法：收集2017年1月~2018年1月于南京医科大学附属口腔医院种植科就诊的奥齿泰种植修复病例曲面体层片。预先记录种植体和覆盖螺丝的尺寸,利用种植体参照法测算覆盖螺丝的高度与直径,比较测算值与实际值,分析该方法的绝对误差。结果：54例患者,共93张曲面体层片被纳入本研究。数据样本符合正态分布,测算值与实际值之间无显著性差异。应用种植体参照法进行后牙区测量的垂直向和水平向绝对误差均小于0.1 mm。结论：种植体参照法应用于曲面体层片后牙区局部测量具有可行性,测量精度较高。