Displacement of the incisive foramen in conjunction with implant placement in the anterior maxilla without jeopardizing vitality of nasopalatine nerve and vessels: a novel surgical approach

Accurate implant placement in the anterior maxilla is essential in achieving optimal prosthetic rehabilitation with proper function and acceptable esthetic and phonetic demands. One of the preferable prosthetic solutions to restore a missing maxillary incisor in young adults is by an implant-supported crown. Bone resorption together with an enlarged incisive foramen, challenge proper implant placement. A simultaneous procedure where the implant osteotomy site penetrated the incisive canal is presented. A configurated cortico-cancellous block graft core was adjusted to fit the foramen while its soft tissue content was pushed back posteriorly but not removed. This procedure was followed by an immediate implant placement. Re-entry at 9 months revealed solid bone support embracing the implant body. Although the size of the incisive foramen diminished significantly, the nasopalatine branches were still evident. No complications and/or loss of sensation were observed.     

Evaluation of the visibility and the course of the mandibular incisive canal and the lingual foramen using cone‐beam computed tomography

Objectives: To assess the visibility and the course of the incisive canal and the visibility and the location of the lingual foramen using cone‐beam computed tomography (CBCT). Methods: In total, 100 CBCT examinations of patients for preoperative planning were used for this study. The examinations were taken using the NewTom 3G CBCT unit, applying a standardized exposure protocol. Image reconstruction from the raw data was performed using the NewTom software. Three experts were asked to assess the visibility of the incisive canal using a four‐point rating scale. The position of the incisive canal was recorded in relation to the lower, buccal and lingual border of the mandible using the application provided by the CBCT software. Results: The incisive canal was definitely visible in 83.5% of the scans and the mean endpoint was approximately 15 mm anterior to the mental foramen. The mean distance from the lower border of the mandible was 11.5 mm and its course was closer to the buccal border of the mandible in 87% of the scans. The lingual foramen was definitely visible in 81% of the scans. Conclusions: The high detection rate of the incisive canal and the lingual foramen in the anterior region of the mandible using CBCT indicates the potentional high preoperative value of CBCT scan for surgical procedures in the anterior mandible. To cite this article :
Makris N, Stamatakis H, Syriopoulos K, Tsiklakis K, van der Stelt PF. Evaluation of the visibility and the course of the mandibular incisive canal and the lingual foramen using cone‐beam computed tomography.
Clin. Oral Impl. Res. 21 , 2010; 766–771.
doi: 10.1111/j.1600‐0501.2009.01903.x     

下颌正中管的锥形束CT成像研究

目的 通过锥形束CT（CBCT）对下颌正中管（MIC）的三维位置、走向及毗邻关系进行测量,为确保颏孔前区域牙种植手术的安全提供依据。方法 回顾80例患者的双侧下颌骨CBCT影像,对MIC的直径和毗邻关系进行测量分析,包括MIC至下颌下缘、下颌牙根尖、下颌骨颊侧壁和舌侧壁,以及双侧颏孔连线平面的垂直距离。结果 80例患者中,63例（占78.75%）的CBCT影像上可以观测到MIC影像,其管径大小为（1.21±0.29）mm。在垂直方向上,MIC距下颌下缘和下颌牙根尖的距离分别为（7.82±1.86）、（7.24±2.82）mm;在颊舌方向上,MIC距下颌骨颊侧壁和舌侧壁的距离分别为（3.80±1.37）、（4.45±1.34）mm;MIC距双侧颏孔连线平面的垂直距离为（5.62±2.21）mm。结论 CBCT通过多平面重建后,可以清晰显示MIC在下颌骨中的三维空间位置、走向及毗邻关系;利用CBCT 对MIC的位置和走行进行研究是可行的。     

Patterns of missing teeth in a population of oligodontia patients

PURPOSE: The purpose of this study was to characterize a population of oligodontia patients and identify patterns of tooth agenesis. MATERIALS AND METHODS: A total of 116 patients with nonsyndromic oligodontia were studied, and the Tooth Agenesis Code (TAC) per quadrant was calculated. Oligodontia was defined as the congenital absence of 6 or more permanent teeth, excluding the third molars. The TAC is a unique number, consistent with a specific pattern of tooth agenesis. The authors suggest the use of an overall TAC with which the dentition throughout the mouth can be presented by a single number. Frequency analysis was used to study the prevalence of various patterns. RESULTS: There was a great diversity of TACs. In the maxilla, agenesis of both premolars and the lateral incisor or the presence of only the central incisor and first molar were the most common patterns. In the mandible, agenesis of the second premolar or both premolars occurred most frequently. CONCLUSIONS: No single pattern of agenesis occurred more than twice when the full mouth was viewed. Hence, the presentation of the dentition in oligodontia is very heterogeneous. Evaluation of treatment strategies in oligodontia patients is a methodologic challenge because homogenous, comparable subgroups of patients are not available.     

Patterns of tooth agenesis in patients with orofacial clefts

Orofacial clefts are a common oral disorder associated with tooth agenesis. As information on the simultaneous absence of teeth can be an aid in treatment planning, a large sample of orofacial cleft patients was examined. The sample consisted of 910 patients with cleft lip and palate. Tooth agenesis was assessed on the basis of at least two panoramic radiographs and patient records. Third‐molar agenesis was determined in 474 patients. Patterns of tooth agenesis were analysed using Tooth Agenesis Code (TAC) values, according to van Wijk & Tan . Per quadrant, at least 90% of patients could be described according to three different patterns. In the maxilla, 85% of patients with tooth agenesis had a TAC‐value of 2, 16, or 18 on either the left side, right side or bilaterally. In the mandible, 90% of patients with tooth agenesis had a TAC‐value of 16, 1 or 2 on either the left side, right side or bilaterally. In patients with tooth agenesis, patterns were symmetrical in the maxilla in 18.8% and in the mandible in 51%. More extended cleft types were associated with a higher prevalence of tooth agenesis. Third‐molar agenesis (prevalence = 22.4%) was significantly related to the prevalence of other absent teeth. These results show which patterns of tooth agenesis can be expected to occur in most orofacial cleft patients.     

切牙管与上颌中切牙位置关系的定量研究

目的 本研究旨在通过研究切牙管与上颌中切牙之间的位置关系,以期为临床治疗及后续研究提供借鉴和参考。方法 选取76例正在进行正畸治疗的成人患者,以PP平面为参考平面,在正中矢状面上定义以下三个测量水平,此三个水平均与PP平面平行。N水平：鼻腭孔高度水平;R水平：上颌中切牙牙根根尖高度水平;I水平：切牙孔高度水平。定义以下测量项目：N水平切牙管唇侧牙槽骨板厚度（NT）;R水平切牙管唇侧牙槽骨板厚度（RT）;I水平切牙管唇侧牙槽骨板厚度（IT）。N水平切牙管宽度（NW）;R水平切牙管宽度（RW）;I水平切牙管宽度（IW）;上颌中切牙根尖距离（R R）;R水平UR1到切牙管距离（RRD）;R水平UL1到切牙管距离（RLD）;I水平UR1到切牙管距离（IRD）;I水平UL1到切牙管距离（ILD）。在CBCT图像上对以上指标进行测量,并对结果进行统计学分析。结果 RRD大于IRD;RLD大于ILD,有统计学差异（P<0.05）。RRD与RLD;IRD与ILD,无统计学差异（P＞0.05）。NW小于RW;RW小于IW,有统计学差异（P<0.05）。NT大于RT,有统计学差异（P<0.05）;NT与IT之间无显著性差异（P＞0.05）;RT与IT之间无显著性差异（P＞0.05）。结论 U1根尖至切牙管平均距离仅为3.5 mm;U1在I水平牙根至切牙管平均距离仅为2.4 mm,应注意在上颌前牙内收时有可能导致牙根根尖及牙根舌侧面的吸收。并且当上颌前牙内收尤其配合压低移动时,应注意有可能造成牙根近中邻面的吸收。     

The Incisive Foramen—a possible reference point

Abstract

The maxilla projects a poor shadow on a lateral radiograph, and its reference points are correspondingly vague. If the mandibular canal is relatively stable in the growing mandible, it is not unreasonable to assume that the incisive foramen may well be so in the maxilla. This anatomical investigation of five cadavers gives evidence to show that the palatine foramen is consistently related to the papilla and can be simply identified with a radio opaque marker. Repetition of accuracy would appear superior to Downs' point “A”.     

Craniofacial and dental features of Axenfeld-Rieger syndrome patients with PITX2 mutations

We aimed to characterize the genetic basis and craniofacial and dental features of Finnish patients with Axenfeld-Rieger syndrome (ARS). Mutational analyses of seven patients in five families were performed by sequencing or comparative genomic hybridization. Phenotypic analysis was based on both clinical and radiographic examinations, as well as on medical data. Lateral cephalometric radiographs of five patients were analysed using Viewbox 3.1-Cephalometric Software. The cephalometric values were compared to Finnish population-standard values of the same age and gender. Two frameshift mutations and three whole gene deletions were detected in five families. Class III skeletal relationship with retrognathic maxilla and mildly retrognathic mandible were detected in all five patients studied. Significant differences compared with the control values were in SNA (P = .0014), ANB (P = .0043) and SNB angles (P = .013). Five patients had anterior crossbite. Six patients showed tooth agenesis. The average number of missing teeth (third molars excluded) was 9 (range 0-15). The tooth agenesis rate was 52% in maxilla and 26% in mandible. Maxillary central and lateral permanent incisors were most often missing (rate 71% equally) while no one lacked canines or first molars in mandible. Two patients had a supernumerary mandibular permanent incisor. Six patients had either taurodontic and/or single-rooted molars. Our results suggest that class III skeletal relationship with maxillary and mandibular retrognathism, anterior crossbite, maxillary incisor agenesis and taurodontic, even pyramidal, roots are common determinants of ARS caused by PITX2 mutations.     

Comparison of the pattern of agenesis in the primary and permanent dentitions in a population characterized by agenesis in the primary dentition

The first aim of this study was to collect a large sample of radiographs from children with congenitally missing teeth (CMT) in the primary dentition and to analyse the local relationship between agenesis of a primary tooth and the presence/absence of its permanent successor. The second aim was to compare, in the same sample, the pattern of agenesis in the primary dentition with the developmental pattern seen in the permanent dentition. 124 dentists from 72 municipalities contributed to the investigation of a total of 213 children. The dentists were asked to lend existing radiographic material from patients with agenesis in the primary dentition. The analysis of the local occurrence of agenesis showed that agenesis of a primary incisor was often but not always followed by agenesis of the succedaneous tooth. In the molar region, agenesis of a primary tooth was in all cases but one followed by agenesis of the succedaneous tooth. Comparison of the pattern of CMT in the primary dentition with the pattern of tooth presence/absence in the permanent dentition in a group of 33 patients, for whom complete radiographic material was available showed that agenesis always occurred in the permanent dentition and that the pattern of agenesis in the permanent dentition differed from that in the primary dentition. Incisors were most frequently missing in the primary dentition and premolars in the permanent dentition. The number of congenitally missing teeth was substantially larger in the permanent dentition than in the primary dentition. Also, permanent teeth that are very rarely congenitally missing were missing in this sample, characterized by the occurrence of agenesis in the primary dentition.     

下颌骨颏孔前区解剖结构的锥形束CT研究

目的 通过锥形束CT（CBCT）分析下颌骨颏孔前区颌骨内的重要解剖结构,提出下颌颏孔前区种植相关手术的安全区域。方法 选取104例患者的CBCT图像资料,观察颏管、下颌切牙管、下颌舌侧管和舌侧孔。对数据进行描述性分析,计算均数和标准差。采用SPSS 19.0软件包对数据进行统计学分析。结果 颏管的发生率为55.29%,平均长度为1.12 mm。舌侧孔及舌侧管的发生率为94.23%,直径平均值为1.77 mm。从下颌第二前磨牙至中切牙,下颌切牙管距唇（颊）侧骨板的距离均小于距舌侧骨板的距离。结论 建议在颏孔前区种植手术或者颏部取骨时,以双侧颏孔前缘6 mm以上,唇侧骨厚度（取骨时）3 mm以内为安全界限;而在下颌前牙区种植时,种植体长度不超过14 mm。     

Mandibular Incisive Canal: Cone Beam Computed Tomography

Purpose: Panoramic radiography is often used to analyze the anatomical structure of the teeth, jaws, and temporomandibular joints. Cone beam computed tomography (CBCT) imaging allows multiple axial slices of the image to be obtained through these anatomical structures. The aim of this study was to assess CBCT compared with panoramic radiography to verify the presence, location, and dimensions of the mandibular incisive canal. Materials and Methods: CBCT scan images and panoramic radiographs of 89 subjects were compared for the presence of the mandibular incisive canal, its location, size, and anterior‐posterior length. The distance between the incisive canal and the buccal and lingual plate of the alveolar bone, and the distance from the canal to the inferior border of the mandible and the tooth apex were also measured. A paired t‐test was used to calculate any significant difference between the two imaging techniques. Results: Eighty‐three percent of the CBCT scans showed the presence of the incisive canal, as did 11% of the panoramic radiographs. The range of the incisive canal diameter, as seen in the CBCT scans, was from 0.4 × 0.4 mm to 4.6 × 3.2 mm. The mean length of the canal was 7 ± 3.8 mm. The distance from the inferior border of the mandible to the canal was 10.2 ± 2.4 mm, and the mean distance to the buccal plate was 2.4 mm. The apex–canal distance (in dentate subjects) was 5.3 mm. Conclusion: The presence, location, and dimensions of the mandibular incisive canal are better determined by CBCT imaging than by panoramic radiography.     

硬腭前份神经支配增龄性变化的临床研究

目的 通过对替牙列期和恒牙列期患者硬腭前份麻醉效果的观察,研究硬腭前份的神经支配以及与个体发育和年龄的关系,为临床前腭部局部麻醉方式的选择以及颌面部神经发育研究提供参考.方法 182例替牙列期患者随机分为鼻腭组和腭大组,分别采用鼻腭神经阻滞麻醉和腭大神经阻滞麻醉.219例恒牙列期患者分为青少年组(13～18岁)和成人组...     

牙颌发育模式及分子机制

牙颌发育模式及分子机制是理解牙颌结构功能的前提，也是再生牙颌组织器官的基础。牙发育分为牙胚发育期、牙冠形成期和牙根形成期。在这一过程中，关键基因具有时间空间的序列性表达。牙源性上皮和间充质相互作用以及釉结等特殊细胞群对牙冠形态精细化、个性化调控，发育成牙。在生物应力、信号调控机制下，牙顺利萌出并发挥功能。牙和颌骨同处发育之中，相互独立又相互依存，相互调控共同发育成为一个有机的整体。牙和颌骨均起源于第一鳃弓，牙或颌骨的发育异常通常会导致彼此的发育缺陷。本文评述牙和颌骨发育的过程，首次阐述稳态微环境在牙发育中的作用以及重点关注颌骨发育中以梅克尔软骨为代表的典型结构和特殊的信号调控机制，提出牙颌一体化发育模式，动态解析牙和颌骨一体化发育过程，并期待未来将这些新模式和机制运用于组织再生。     

正常[牙合]青少年不同垂直骨面型切牙区牙槽骨宽度研究

目的：比较个别正常[牙合]青少年不同垂直骨面型切牙区牙槽骨宽度的差异。方法：选取个别正常[牙合]青少年高角组23名,均角组25名,低角组24名,测量其头颅侧位片上的上下颌切牙区牙槽骨宽度的相应指标,利用SPSS14．0统计软件对测量结果进行比较分析。结果：个别正常[牙合]UP值、IP值和LA值在低角组与高角组、均角组的差别具有统计学意义（P〈0．05）,高角组与均角组的差别无统计学意义;UA值在高角组、均角组、低角组的差别无统计学意义（P〉0．05）;UH值在高角组与低角组、高角组与均角组的差别具有统计学意义（P〈0．05）,但低角组与均角组的差别无统计学意义;LH值在高角组与低角组的差别具有统计学意义（P〈0．05）,其余两组均无统计学意义。结论：个别正常[牙合]青少年上下颌切牙区牙槽骨宽度与垂直骨面型有关,高角组上切牙根尖部腭侧,下颌切牙根尖部唇舌侧的牙槽骨厚度较薄,而低角组相应处的牙槽骨较厚。     

Clinical assessment and surgical implications of anatomic challenges in the anterior mandible

Background: The anterior mandible is generally considered a rather safe surgical area, involving few risks of damage to vital anatomic structures. Nevertheless, both neurosensory disturbances and hemorrhages have been reported after implant surgery in that particular area. Purpose: With the increasing demand for oral implant placement, the anatomy of the anterior mandible should receive more attention. This review will focus on the anatomic peculiarities of the anterior mandible and the related clinical implications. Methods: The scientific evidence on the anatomic, histologic, physiologic, and clinical aspects of the neurovascularization of the anterior mandible will be reviewed. Results: Surgical complications may be attributed to the existence of a mandibular incisive canal with a true neurovascular supply. Potential risks may also be related to the presence of the lingual foramen and anatomic variations, such as an anterior looping of the mental nerve. Conclusions: Preoperative radiographic planning for oral implant placement in the anterior mandible should therefore not only consider all esthetic and functional demands but should also pay particular attention to the anatomic peculiarities of this region to avoid any neurovascular complications.     

Location and Presence of Permanent Teeth in a Complete Bilateral Cleft Lip and Palate Population

Objective:To describe the location and presence of permanent teeth in nonsyndromic complete bilateral cleft lip and palate patients from the Manitoba Centre for Craniofacial Difference.Materials and Methods:Records of 1570 patients dating back to 1958 were assessed in this retrospective chart review.Results:Thirty-eight patients met the inclusion criteria, providing 76 cleft site teeth: A tooth on each side of the cleft was considered to have developed from a single lateral incisor tooth bud. The pattern M was assigned when a tooth was found mesial to the cleft, D when distal, MD when mesial and distal and AB if none was found. Pattern M was noted 9.2% of the time; D, 47.4%; MD, 5.3%; and AB, 38.2%. Teeth outside the cleft site: In the maxilla, agenesis occurred in 11.9% of second premolars and 10.5% of central incisors. In the mandible, agenesis occurred in 4.0% of second premolars, 2.6% of lateral incisors, 2.6% of central incisors, and 2.6% of second molars.Conclusions:The lateral incisor was most commonly found distal to the cleft. Agenesis of the lateral incisor and teeth outside the cleft were more common than in noncleft populations.     

下颌切牙管的三维空间分布规律研究及对颏部取骨的范围探讨

目的:利用口腔锥形束CT(CBCT)探寻下颌切牙管(MIC)在下颌骨内的一般分布规律,为降低患者颏部截骨术后的神经并发症风险提供影像学依据.方法:收集80例患者下颌骨的CBCT影像资料,评估MIC在颏孔间区各牙位下方的检出率和清晰度,并对MIC的直径及其与下颌骨各平面之间的距离进行测量.结果:MIC的检出率为52.5％...     

Radiographic observations on root resorption in the primary dentition.

In order to construct standardized charts for root resorption in the primary dentition of Japanese children, we investigated the stages of resorption (1/4, 1/2 and 3/4 of the root) based on the criterion of Fanning, et al. using 11,167 panoramic radiographs (5,759 of boys and 5,408 of girls). The following information was obtained. 1) The root resorption for a tooth on one side was the same as for its counterpart on the other side regardless of differences in sex or arch. 2) The average age for each root resorption stage was lower in girls than in boys regardless of differences in sex or arch. 3) The average age for each root resorption stage was lower in the mandible than in the maxilla for every tooth. 4) In the maxilla, the period between 1/4 to 3/4 resorption of the root was greater in the primary molars than in the primary anterior teeth. However, the opposite was true in the mandible. 5) Although no difference was observed between the maxilla and the mandible in the resorption period for the primary incisors and canines, the resorption time for the primary molars was greater in the maxilla than in the mandible. 6) When the relationship was observed between the resorption stages for each tooth and the calcification stages for the corresponding successional permanent tooth. a) With the exception of the maxillary and mandibular canines, the average age for 1/4 resorption of the primary root corresponded to the period between completion of the permanent crown and initial root formation of the successional permanent tooth. b) With the exception of the maxillary and mandibular canines, and the mandibular second premolars, the average age for 3/4 resorption of the primary root corresponded to the period between 1/4 and 1/2 formation of the root of the successional permanent tooth. From these results, standardized charts were constructed for the resorption of the roots of primary teeth in Japanese children. These standardized charts are useful in daily clinical practice in such areas as endodontic treatment of primary teeth and orthodontics.     

Appearance of anatomical structures of mandible on panoramic radiographs in Iranian population

Abstract

Purpose. Currently panoramic radiography is used for diagnosis of dental and bone lesions, but anatomical structures also can be seen and may be useful in dental managements. This study aimed to investigate the visibility of some important mandibular features relating to neurovascular structures in Iranian population. Materials and methods. Panoramic radiographs were taken by Planmeca machine from 412 patients using standard exposure. The position of patient was in compliance with standard protocol. Then mandibular incisive canal was evaluated and data were analyzed statistically. Results. Mental foramen, anterior loop of mental nerve and incisive canal could be observed in 84.2, 66 and 51.7% of the cases. Respectively, lingual foramen was observed in only 6.1% of the radiographs. Gender doesn't affect on the visibility of these structures. There was a relationship between mandibular foramen and canal with age. Conclusion. Mandibular incisive canal was considered in 51.7% of cases, it was observed that the result obtained was more than those of other researches.     

Isolated oligodontia: a case presentation and review of the literature

Tooth agenesis is a common developmental anomaly that appears in 2.2-10% of the general population (excluding agenesis of third molars). Congenital tooth agenesis can be either Hypodontia (agenesis of fewer than six teeth excluding third molars) or Oligodontia (agenesis of more than six teeth excluding third molars). Oligodontia can occur either as an isolated condition (non-syndromic oligodontia) or be associated with cleft lip\palate and other genetic syndromes (syndromatic oligodontia). The purpose of this article is to present an unusual case of non-syndromic oligodontia and describe the dental treatment for this condition. The patient was a 25 years old healthy male with a chief complaint of multiple teeth agenesis and TMJ dysfunction. The family history revealed that the mother, grandmother and siblings have also multiple teeth agenesis. Clinical examination revealed missing of nine teeth in the maxilla (12,13, 15,15, 17, 23, 24, 25, 27) and 10 teeth in the mandible (32, 33, 34, 35, 37, 42, 43, 44, 45, 47). The patient's dental treatment plan included preparing provisional over-dentures, orthodontic treatment and dental implants (after extractions of the deciduous teeth). In the discussion of the article the pathology and the genetics of oligodontia are reviewed.