Forensic dentistry in the identification of victims and assailants

The teeth are the least destructible part of the body and may remain more or less intact for many years beyond death. In addition, because of their stability in a biological sense, and because during their formation disease may affect the hard tissues of the teeth themselves, they contain information about the physiological and pathological events in the life of the individual which remain as markers within the hard tissues of the teeth. Therapeutic activity by a dentist in the form of restorations and prostheses may modify an individual's dentition in a more or less unique manner. It is the role of the forensic dentist to assess this biological and chemical information, and use it in the identification of an unknown body. The teeth may also be used to inflict injury on a victim in the form of a bite. The resulting bite mark may not only indicate the degree of aggression during the assault but if sufficient details are available within it, may enable the forensic dentist to determine the identity of the assailant. This important aspect of forensic dentistry is commonly required in non-accidental injuries to children and in instances of grievous bodily harm, rape and murder of child or adult.     

单侧最大紧咬软硬物对咬合力和咀嚼肌的影响

 目的 研究单侧最大紧咬不同硬度物质对咬合力和咬肌、颞肌前束的肌电值的影响。方法 在受试者一侧下颌第2前磨牙与第1磨牙上放置聚氯乙烯(polyvinyl chloride,PVC)软片,对侧同名牙放置面团期丙烯酸树脂(acrylic resin, AR),最大紧咬时制取丙烯酸树脂片为硬物;使用T-ScanⅢ咬合分析仪和Bio-Pak肌电图仪测量受试者在牙尖交错位(intercuspal position, ICP)和单侧咬合软硬物下双侧最大紧咬时的咬合力和咬肌(masseter muscle, MA)、颞肌前束(temporalis-anterior muscle, TA)的肌电值。结果 (1)ICP最大紧咬时,双侧MA肌电值、双侧TA肌电值均无明显差异 (P>0.05); (2)单侧最大紧咬时,咬合侧与咬合对侧MA肌电值无明显差异(P>0.05);而咬合侧TA肌电值分别为(147.75±31.37)μν、(145.70±35.08)μν,均明显大于咬合对侧(115.87±24.08)μν、(121.24±22.78)μν,差异均有统计学意义(P<0.05); (3)单侧最大紧咬时,MA肌电值与ICP最大紧咬时相比差异无明显统计学意义,咬合对侧TA肌电值(147.75±31.37)μν和(145.70±35.08)μν均明显小于ICP最大紧咬时的TA肌电值(136.88±29.54)μν,差异有统计学意义(P<0.05);(4)单侧咬合时,所有受试者(20/20例)均出现了咬合对侧接触现象。单侧最大紧咬时软物的咬合力为(9174.60±955.29)raw,明显大于硬物的咬合力(6156.70±979.27)raw,差异有统计学意义(P<0.05);但软物最大紧咬时的MA和TA肌电值分别与硬物比较差异无统计学意义。结论 与硬物相比,软物对咬合力的影响相对较小,但不同硬度咬合物对咀嚼肌肌电值无明显影响。     

Surface laser scanning to routinely produce casts for patient immobilization during radiotherapy

Immobilization casts are used to reduce patient movement during the radiotherapy of head and neck and brain malignancies. Polyethylene-based casts are produced by first taking a Plaster of Paris 'negative' impression of the patient. A 'positive' mould is then made, which is used to vacuum form an immobilization cast. Taking the 'negative' cast can be messy, stressful for patients and labour intensive. Recently, lightweight hand-held laser surface scanners have become available. These allow an accurate 3-D representation of objects to be generated non-invasively. This technology has now been applied to the production of casts for radiotherapy. Each patient's face and head is digitized using the Polhemus FastSCAN (Polhemus, Colchester, VT, USA) scanner. The electronic data are transferred to a computer numerical controlled mill, where a positive impression is machined. The feasibility of the process was examined, the labour required and radiation therapists' satisfaction with aspects of the produced masks assessed. The scanner-based method of mask production was found to be simple, accurate and non-invasive. There was a reduction in radiation therapist labour required. Masks produced with the scanner-based method were reported to result in improved mask fitting, daily reproducibility, patient immobilization and patient comfort.     

Peripheral ossifying fibroma in the oral cavity: CT and MR findings

We report a case of peripheral ossifying fibroma arising from the anterior oral cavity in a 12-year-old boy. CT and MR scans showed a large exophytic soft tissue mass overlying the anterior hard palate and maxillary alveolar ridge. The tumour revealed peripheral calcification without adjacent bone changes.     

Radiographic manifestations of the temporomandibular joint in a case of Proteus syndrome

Proteus syndrome is a rare disorder with progressive asymmetrical and disproportionate overgrowth of various tissues of the body. The syndrome is characterized by a wide range of malformations, including craniofacial deformities. Extraoral examination revealed several of the classical craniofacial features of Proteus syndrome: pronounced hemifacial hypertrophy, macrodactyly and hyperostosis. Intraoral examination revealed a high arched palate and gingival hyperplasia. Other findings were unilateral enlargement of the tongue, alveolar growth and dilaceration of the roots of the teeth. There were severe degenerative changes and deformities in the left temporomandibular joint but the oversized condyle was asymptomatic; there was no pain, limitation and deviation at mouth opening. Treatment was not necessary owing to the asymptomatic situation but periodic follow-up with clinical and radiographic examination was considered. The aim of this article is to describe the radiographic manifestations of an asymptomatic condyle malformation and other craniofacial, oral and dental findings in a 33-year-old female patient with known Proteus syndrome.     

外伤性牙槽损伤固定方法的临床研究

目的　分析方丝弓托槽技术和牙弓夹板技术在外伤性牙槽损伤的临床应用。　方法　随机将 91例外伤性牙槽损伤需进行单颌固定的患者分为两组 ,共 134颗牙齿 ,分别采用方丝弓托槽技术和常规牙弓夹板技术固定 ,记录患者复诊过程中固定装置的稳固情况 ,以及半年后临床疗效和牙周相关指标 ,并进行统计学处理。　结果　两组患者复诊过程中固定装置稳固情况和在牙龈炎、牙周袋形成、牙槽骨吸收的改变上差异有非常显著性意义 (P <0 .0 1) ,在临床疗效评定结果上差异无显著性意义 (P >0 .0 5 )。　结论　方丝弓托槽技术是治疗外伤性牙槽损伤可靠的单颌固定方法     

High-resolution CT of the temporal bone: a modified baseline.

High-resolution computed tomography (CT) of the temporal bone, particularly axial scanning on a baseline parallel to the orbitomeatal line, produces radiation exposure to the patient's lenses. The authors evaluated the radiation dose to the lens and the visualization of temporal bone structures with use of scanning along the orbitomeatal line and on a line parallel to the hard palate. Evaluation of visualization was performed by five radiologists, with high-resolution CT scans of 45 healthy patients, and the chi 2 test was performed for comparison. The change of the baseline from the orbitomeatal line to a line parallel to the hard palate decreased the radiation dose to the lens from 12.7 cGy to 0.274 cGy and improved visualization of the stapes superstructure and the tympanic portion of the facial nerve canal, although visualization of the incus body, incudostapedial joint, lateral semicircular canal, and oval window was of equal quality. Therefore, the authors recommend a new baseline parallel to the hard palate for use at high-resolution CT of the temporal bone.     

喉罩全麻及紧急通气的临床应用分析

目的　总结在全麻与紧急通气中应用喉罩的经验。方法　根据病人体质量 ,选择适宜的喉罩。病人仰卧 ,头放正位 ;操作者一手插入病人后枕部 ,使病人头后仰 ;另一手第 1,2指捏住喉罩通气管的根部 ,连接罩子之处 ,将第 3指按住下颌 ,将下颌前推 ,使病人张口达最大限度 ,轻轻将喉罩深入口内 ,以喉罩的尖端指向病人的硬腭并沿其生理弯曲送下 ,直到不能再送入为止。结果　 166例病人中 ,,1次置入成功 14 3例 ,2次置入成功 17例 ,第 3次用中指引导置入 5例 ,用喉镜置入 4例 ,1例经反复调整后 ,仍明显漏气而改换气管内插管。喉罩放置时间 1 5h～ 3d ,平均 2 65h。副作用 :漏气 6例 ,拔除喉罩后咽部不适 2例。结论　喉罩的应用为呼吸道管理和建立提供了一种行之有效且简便的手段。     

Shock absorption capacities of mouthguards in different types and thicknesses

Although sports mouthguards provide protection against trauma, dentoalveolar injuries can still occur with the mouthguards in place. This study examined the effect of mouthguard protection in an in vitro model. A simulated maxilla, out of a polymethylmethacrylate (PMMA) arch, containing replaceable resin teeth, was used to assess the performance of different mouthguard designs. "Boil and bite" and custom-fitted mouthguards (ethylene vinyl acetate [EVA]) laminated with hard (poly-vinyl chloride [PVC]) or soft labial intermediate EVA layers were fabricated according to manufacturers' instructions. A steel ram was dropped onto the mouthguards at the maxillary incisor region. Changes in voltage, which were induced by a strain gauge at the back of the upper left incisor, were measured with an amplified voltmeter. Data were analysed by ANOVA at a significance level of 0.05. "Boil and bite" and mouthguards layered with silicone or with small hard PVC inserts of 1.5 mm thickness demonstrated less absorption and differed significantly from the other mouthguard systems (p < 0.05). Bilaminated mouthguards with hard PVC inserts of 0.8 mm, 1.5 mm or 2 mm thickness showed no significant differences to those with 1.5 mm thick (EVA) inserts. The absorption rates amounted to 33 % compared with the unprotected tooth.     

Dental fracture and chocolate candies: Case report

A complaint by a customer to a food company claimed that the consumption of a chocolate candy fractured his anterior teeth, due to its hard consistency. Fragments of the fractured teeth and the chocolate candy that supposedly caused it were collected, examined and photographed. Fragments presented caries, large restorations, and suggested previous endodontic treatment. To evaluate causation, the food company requested a laboratory analysis, which simulated the human bite on chocolate candies of the same brand. Human teeth were assembled in a simulating device of masticatory functions of apprehension and incision. Teeth used were either sound or with non-restored endodontic accesses, to simulate previous conditions of the collected fragments. Twenty chocolate candies, cooled in a freezer to 0 °C for 2 h were used as test foods, and were positioned between the teeth of the device at the moment of the test. The set was put in a dynamometer, programmed to apply increasing forces (rate of advance of 5 mm/min), until rupture (either of the specimen or of the teeth). The applied force, in N, at the time of fracture was recorded and analyzed. The average force to fracture the test food was 233.23 N. No tooth was fractured in the experiment. Forces ranging from 191.3 to 275.2 N, applied to chocolate candies were not sufficient to neither fracture human teeth nor cause any structural damage. It was concluded that the dental fracture occurred because of previous oral health conditions of the customer.     

Nasal teeth: report of three cases

The ectopic eruption of the teeth into the nasal cavity is a rare phenomenon. We report cases: two involving the nasal cavity and one involving the hard palate and complicated by Aspergillus rhinitis. We describe the clinical and radiologic presentation of these cases and discuss their etiology, complications, diagnosis, and treatment.     

两种麻醉技术在上颌前牙牙周治疗中的应用体会

目的 探讨两种麻醉技术在上颌前牙牙周治疗中的应用体会.方法 将需要在局部麻醉条件下对上颌前牙进行牙周治疗的患者随机分为2组,试验组采用单颗牙麻醉(STA)系统行上牙槽前、中神经麻醉(AMSA),对照组采用传统手推注射法行上颌前牙骨膜上麻醉.注射后,患者均通过视觉模拟评分法(VAS)评定注射时的疼痛程度,在治疗过程中医师评定麻醉效果.结果 试验组与对照组的麻醉效果均较好,统计学检验无显著差异(P＞0.05),试验组注射疼痛的VAS平均值低于对照组(P＜0.01).结论 采用STA系统行AMSA在上颌前牙牙周治疗中的麻醉效果与传统的手推注射法相当,但前者的注射疼痛远较后者小.     

Locally advanced verrucous carcinoma of the oral cavity

Background

Oral verrucous carcinomas are locally invasive but rarely metastasize. Current treatment options include surgery and external beam radiotherapy (EBRT). In medical inoperable patients or irresectable tumors, high-dose-rate (HDR) brachytherapy is a valid alternative.

Case

We present an 85-year-old man with functionally irresectable cT3N0M0 verrucous carcinoma superficially spreading along the upper alveolar ridge to the retro-alveolar triangle, with infiltration of the left soft and hard palate and buccal mucosa. Using a customized intraoral mold, this patient was treated with HDR brachytherapy delivering a dose of 48 Gy in 12 fractions three times per week. Treatment was well tolerated, and after prolonged confluent mucositis the tumor is in complete remission.

Review of literature and conclusion

The scarce literature on customized mold HDR brachytherapy in maxillary tumors is reviewed and recommendations for other head and neck tumors are given.     

Soft tissue removal by maceration and feeding of <Emphasis Type="Italic">Dermestes</Emphasis> sp.: impact on morphological and biomolecular analyses of dental tissues in forensic medicine

Maceration techniques remove soft tissue by the destruction of biomolecules, but the applied techniques may also affect the morphology and the molecular integrity of the hard tissue itself. The impact of seven different techniques for soft tissue removal on morphological and biomolecular parameters of teeth and dental tissues was systematically examined. All methods tested showed significant changes in dental morphology and in the molecular integrity of DNA and the dental proteins, as revealed by aspartic acid racemisation (AAR). In forensic casework this may have severe impacts on the results of morphological methods (e.g. age estimation based on root translucency) and of biomolecular analyses (e.g. age estimation based on AAR and DNA analysis). Therefore, age estimation based on AAR should not be applied to tissue treated in such a manner, and it is recommended that teeth for analysis should be extracted before soft tissue removal. DNA in the hard tissue seems to be less susceptible to soft tissue removal than proteins, and several of the tested maceration techniques appear not to have a damaging effect on DNA. Generally, the indication for soft tissue removal demands a careful case management to avoid methodological collisions.     

A simple eye-lens shielding technique compatible with independent jaws of a linear accelerator.

A technique, compatible with accelerators having independent collimators, is presented, which greatly simplifies alignment of pencil eye-lens shields. The patient is placed so that the eye to be shielded is on the central axis of the beam and the accelerator's collimators are adjusted independently to define the field. A divergent lead shield 14 cm long is suspended from a wire that hangs along the central axis from a blocking tray in its usual location. The suspension length is variable and adjusted on the first day so that the shield is about 1 cm above the patient's eye. On subsequent treatment days, the wire is simply put in place on the tray with no further adjustment required. This technique reduces setup time and makes the shield positioning highly reproducible.     

全瓷冠联合牙槽突磨削治疗上前牙前突伴骨性前突

目的观察全瓷冠联合牙槽突磨削治疗上前牙前突伴轻中度上颌骨骨性前突的临床治疗效果。方法选取我科门诊收治的56例上前牙前突伴轻中度上颌骨骨性前突的病例,共412颗牙,对牙槽突进行定量磨削,切除部分牙龈,作全瓷冠内收上前牙。术后1、3、6个月和1年随访。结果全瓷冠的临床效果评价：边缘完整性、解剖外形、表面光滑度、颜色均为A。牙龈临床评价：第1个月都是A,3个月有2个B,6个月有5个B和1个C,1年有3个B。修复后1年患者满意度评价：“非常满意”43例,“基本满意”13例,无“不满意”,满意度77％。专业医师评价优良率：纠正上前牙前突98．5％,减轻深覆颌深覆盖84．5％,与邻牙匹配度97．5％,整体轮廓96．6％。结论采用全瓷冠联合牙槽突磨削是治疗上前牙前突伴轻中度上颌骨骨性前突的有效方法,其远期效果有待进一步观察。     

1,2-二氯乙烷中毒性脑病的临床及影像学特点分析

目的：探讨亚急性l,2-二氯乙烷中毒性脑病的临床特点。方法回顾性分析1例临床诊断明确的l,2-二氯乙烷中毒性脑病患者的临床表现、辅助检查及救治过程,并结合文献总结其临床特点。结果患者亚急性起病,突出表现为头痛、呕吐、意识障碍等严重高颅压症状及记忆力下降、反应迟钝、理解力及计算障碍等高级皮层功能受损症状;甲状腺功能减退;头颅影像示双侧大脑半球弥漫性脱髓鞘病变,脑组织肿胀,脑室受压,双侧小脑齿状核、双侧苍白球病变,病灶在MRI上T1WI呈低信号,T2WI高信号,在头CT呈低密度影。治疗期间因腰穿脑压正常而停用脱水药物后病情加重,经长期、足量脱水剂、糖皮质激素治疗后症状明显好转,发病6个月后患者临床症状、影像学及甲状腺功能恢复正常。结论 l,2-二氯乙烷中毒性脑病脑水肿严重,持续时间长,充分控制脑水肿是治疗成功的关键。     

Thermoforming plastic in lead shield construction

Radiation treatments using low energy X-rays or electrons frequently require a final field defining shield to be placed on the patient's skin. A custom made lead cut-out is used to provide a close fit to a particular patient's surface contours. We have developed a procedure which utilizes POLYFORM thermoplastic to obtain a negative mold of the patient instead of the traditional plaster bandage or dental impression gel. The Polyform is softened in warm water, molded carefully over the patient's surface, and is removed when "set" or hardened, usually within five minutes. Then lead sheet cut-outs can be formed within this negative. For shielding cut-outs requiring thicker lead sheet, a positive is made from dental stone using this Polyform negative. We have found this procedure to be neat, fast and comfortable for both patient and the dosimetrist.     

Transient forces generated by projectiles on variable quality mouthguards monitored by instrumented impact testing

OBJECTIVES: (a) To determine the force-time trace that occurs when a spring mounted simulated upper jaw is impacted; (b) to examine if mouthguards of variable quality have significant influence on such force-time traces; (c) to attempt to relate physical events to the profile of the force-time traces recorded. METHODS: A simulated jaw, consisting of ceramic teeth inserted into a hard rubber arch reinforced with a composite jawbone, was fitted with various mouthguards as part of a previous round robin study. A clinical assessment distinguished good, bad, and poor mouthguards, and these were each fitted to the jaw, which was then submitted to instrumental impact tests under conditions expected to produce tooth fractures. The force-time trace was recorded for such impact events. RESULTS: The spring mounting method caused two distinct peaks in the force-time trace. The initial one was related to inertia effects and showed an increase in magnitude with impactor velocity as expected. The second peak showed features that were related to the differences in the mouthguards selected. CONCLUSIONS: The use of a force washer within a conical ended impactor enabled force-time traces to be recorded during the impact of a spring mounted simulated jaw fitted with mouthguards of variable quality. The spring mounting system causes an initial inertial peak followed by a second peak once the spring mount has fully compressed. Good fitting guards, which keep most teeth intact, result in high stiffness targets that in turn generate high reaction forces in the impactor. If the spring mounting is omitted, the two peaks are combined to give even higher reaction forces. The force-time trace offers some potential for assessing both overall mouthguard performance and individual events during the impact sequence. Mouthguards with good retention to the jaw remained attached during the impact event and helped to preserve the structural integrity of the target. This in turn developed high forces in the second part of the force-time trace. Guards that detached during impact and allowed tooth fractures showed lower forces in the second part of the test. The force profile measured offered some quantitative support to, and agreement with, the observed clinical quality of the mouthguards.     

改良型富血小板纤维蛋白预防下颌阻生智齿拔除术后并发症的效果

 目的 探讨应用改良型富血小板纤维蛋白(advanced platelet-rich fibrin,A-PRF)预防下颌阻生智齿拔除术后并发症的效果。方法 选取20例需拔除双侧下颌智齿患者,每名患者随机筛选一侧牙槽窝,行A-PRF填充(试验组);另一侧行常规缝合处理(对照组)。比较术后1、7d两侧拔牙窝疼痛程度、疼痛发生率及软组织肿胀程度,同时评价不同处理方式后张口度及术后3个月第二磨牙远中牙周袋深度。结果 试验组牙槽窝术后1d后疼痛分级为4.25,低于对照组的6.20(P<0.05),且疼痛发生比例低于对照组牙槽窝。随着时间延长,两侧牙槽窝的术后疼痛级别都显著下降。拔牙后1 d,试验组牙槽窝肿胀度为(0.59±0.09)cm,张口度为(3.79±1.25)cm,皆显著低于对照组(P<0.05);7 d后对照组和试验组两侧肿胀程度分别为(0.025±0.09)cm和(0.013±0.07)cm,两组无统计学差异;术后3个月两侧第二磨牙远中牙周袋探诊深度分别为(4.61±0.27)mm和(3.39±0.29)mm(P<0.05)。结论 A-PRF的应用可以有效减少下颌阻生智齿拔牙术后并发症的发生。