Epidermis and Enamel: Insights Into Gnawing Criticisms of Human Bitemark Evidence.

Critics describe forensic dentists' management of bitemark evidence as junk science with poor sensitivity and specificity and state that linkages to a biter are unfounded. Those vocal critics, supported by certain media, characterize odontologists' previous errors as egregious and petition government agencies to render bitemark evidence inadmissible. Odontologists acknowledge that some practitioners have made past mistakes. However, it does not logically follow that the errors of a few identify a systemic failure of bitemark analysis. Scrutiny of the contentious cases shows that most occurred 20 to 40 years ago. Since then, research has been ongoing and more conservative guidelines, standards, and terminology have been adopted so that past errors are no longer reflective of current safeguards. The authors recommend a comprehensive root analysis of problem cases to be used to determine all the factors that contributed to those previous problems. The legal community also shares responsibility for some of the past erroneous convictions. Currently, most proffered bitemark cases referred to odontologists do not reach courts because those forensic dentists dismiss them as unacceptable or insufficient for analysis. Most bitemark evidence cases have been properly managed by odontologists. Bitemark evidence and testimony remain relevant and have made significant contributions in the justice system.

Bite marks: physical properties of ring adhesion to skin--phase 2.

Bite Marks: This study demonstrated that surface wetness was the most influential factor affecting ring adhesion to skin. Also, chemical depilatories and shaving creams were to be avoided when cleaning the skin. The second phase of this research examines the tensile stress needed to rupture the bond between TAK(®) hydroplastic, three new cyanoacrylates, and pigskin with particular consideration for temperature variations. This study also considers solubility issues of different cyanoacrylates in 10% formalin. Finally, the Dorion Type V bitemark excision technique could significantly reduce the risks of tissue distortion when used in conjunction with the following methods and materials. The skin should be devoid of moisture, razor shaved, and cleaned with dishwashing detergent and 98.9% ethanol while avoiding the use of shaving creams and/or chemical depilatories where ring placement is anticipated. The use of unopened cyanoacrylate is encouraged with Permabond(®) as the cyanoacrylate of choice.

Bite marks: physical properties of ring adhesion to skin-phase 1.

Unsupported excised skin may shrink by as much as 50% or more. In 1981, a method was developed for ring adhesion to skin with the goal of minimizing tissue distortion upon excision. Five modified versions of the technique bearing the author's name followed (Dorion types I, II, III, IV, and V). The scientific literature reveals little supporting empirical evidence for the preferential use of one adhesive/suturing technique over another. This study compares the use of various bonding materials (Loctite Super Glue gel(®) , Dermabond™, Vetbond™), cleaning agents (ethanol, dishwashing liquid, and shaving cream), and depilatory (Veet(®) ) on the effects of ring adhesion to skin. The conclusions indicate that surface wetness is the most influential factor affecting ring adhesion to skin, followed by the type of bonding material, its "freshness," and by the cleaning agent used to prepare the skin. The use of a depilatory or shaving cream is to be avoided.

Inquiry into the scientific basis for bitemark profiling and arbitrary distortion compensation.

Prediction of dental characteristics from a bitemark (bitemark profiling) and arbitrary photographic distortion compensation are two practices proposed in bitemark analysis. Recent research on the effect of inherent skin tension properties in bitemark analysis suggests that these practices are subject to review. A biting apparatus was used to create 66 bitemarks in human cadaver skin. The bitemarks were photographed, sized 1:1, and evaluated with Adobe Photoshop. Metric/angular measurements and hollow volume dental overlays were employed. Distortion produced was calculated and assessed. Results showed distortional ranges were nonuniform both between bites, as well as within each bite. Thus, enlarging/decreasing the photograph uniformly would not correct the distortion that resulted. With regard to bitemark profiling, 38% of the bites created patterns that could be misleading if profiled. Features were present/absent that were inconsistent with the biter's dentition. Conclusions indicate bitemark profiling and arbitrary distortion compensation may be inadvisable.

The response of skin to applied stress: investigation of bitemark distortion in a cadaver model.

Knowledge of distortional properties of skin is important in bitemark analysis. Thus, the response of skin to stress from bites was investigated. Four sets of models were created from the dentition of one individual. Anterior teeth were systematically removed to vary contact surface area. A biting apparatus was constructed with an integrated load cell. Forty-six bites were created perpendicular to Langer lines on six cadavers. Rate of force application and bite pressure were controlled. Metric/angular measurement and hollow volume overlays were employed. Distortion produced by each dentition was calculated and assessed. Results showed that as teeth impressed loose tissue, mesial/distal distance increased, angles of rotation flattened, and inter-canine distance lengthened. An opposite effect was seen in tight tissue. When the surface area of the dentition was reduced, a mixture of these effects was observed. Conclusions indicated that stiffness of the tissue was the most important variable in bitemark distortion.

Biomechanical factors in human dermal bitemarks in a cadaver model.

In bitemark analysis, the forensic odontologist must consider how the biomechanical properties of the skin contribute to distortion of the bitemark. In addition, one must consider how the bitemark can be distorted by postural movement of the victim after the bite has occurred. A fundamental review of the architecture and biomechanical properties of the dermis is described and evaluated through bites made on cadavers. In order to assess distortion, 23 bites from a single characterized dentition were made on un-embalmed cadaver skin. Bite indentations were photographed. Following various body manipulations they were re-photographed in different positions. Hollow volume overlays of the biting dentition were constructed, and metric analysis of the dentition and all bitemarks was completed. The overall intercanine, mesial to distal, and angle of rotation distortion was calculated. Of the 23 bites made, none were measurably identical, and in some cases, dramatic distortion was noted.

Uniqueness of the dentition as impressed in human skin: a cadaver model.

Bitemark interpretation assumes that the human dentition is unique and that its attributes can be accurately transferred to skin. A cadaver model was used to investigate whether the correct biter could be determined from similarly aligned dentitions once the dentitions were impressed in human skin. One-hundred dental stone models, which were measured and determined to be unique, were divided into 10 groups based upon similarities of mal-alignment patterns. One model was randomly selected from each group and bites were produced on unembalmed human cadavers. Metric/angular measurements and hollow volume overlays of the models were compared with the bites made. The percentage of dentitions from each group as well as the 100 dental model population that could not be excluded as the biter was determined. Results showed difficulty distinguishing the biter from individuals with similarly aligned dentitions and in some cases, an incorrect biter appeared better correlated to the bite.