# A Technique to Capture, Analyze, and Quantify Anterior Teeth Rotations for Application in Court Cases Involving Tooth Marks

> Every front tooth sits at a slight twist, and that twist shows up in a bite mark. Forensic dentists in South Africa measured the twist of each front tooth in 300 volunteers and worked out which angles are common and which are rare, so that a rare feature in a bite mark can be given the weight it deserves in court. Like reading a track, it is all about knowing how unusual a feature really is.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/2006-bernitz-van-heerden-technique-capture-analyze-quantify/

## Citation and access

- **Authors:** Herman Bernitz, Willie F.P. van Heerden, Tore Solheim and Johanna H. Owen
- **Year published:** 2006
- **Journal or source:** Journal of Forensic Sciences
- **Full citation:** Bernitz, H., van Heerden, W. F. P., Solheim, T. and Owen, J. H. 2006. A technique to capture, analyze, and quantify anterior teeth rotations for application in court cases involving tooth marks. Journal of Forensic Sciences 51(3): 624–629.
- **DOI:** 10.1111/j.1556-4029.2006.00114.x
- **Access status:** Publisher link only
- **Where to find it:** https://doi.org/10.1111/j.1556-4029.2006.00114.x

## Tags

- **Region:** Africa > South Africa
- **Methods and technology:** Analysis of variance (ANOVA); Descriptive statistics
- **Data type:** New field data
- **Observer qualification:** Not needed
- **Discipline:** Forensics; Taphonomy
- **Year published:** 2006

## Detailed keywords

- **Species:** Studied: humans (the front teeth of 300 volunteers, 155 men and 145 women aged 16 to 75). No animals.
- **Location and habitat:** Bronkhorstspruit area, South Africa. Bites were taken at institutions and, where age, race or sex groups were under-represented, at private homes. Plaster models were cast at Highveld Dental Laboratory, Middelburg, Mpumalanga, South Africa.
- **Topics:** forensic dentistry (forensic odontology); bite marks and tooth marks as crime-scene evidence in skin, food and objects; rotation of the six upper and six lower front teeth (canine to canine); measuring tooth rotation from wax bite impressions; how common or rare a feature is (its discrimination potential); weighting features by frequency rather than by experience alone; dentures in bite mark cases; a rape case example. Inconsistencies in the paper: Table 1 is captioned “mandibular” (lower) teeth but its column is headed “Upper Teeth”; Methods give age groups of 16 to 35 years and 35 years and older, while the Results and table captions use 15 to 35 and above 36 (and the volunteers were aged 16 to 75); the Discussion refers to the classification in “Tables 2 and 3”, which is in Tables 3 and 4.
- **Statistics or models:** Means, standard deviations, minimum and maximum rotation values by age, race and sex group; 1st, 5th, 95th and 99th percentiles used to class rotations as common, uncommon (5 in 100 or fewer) or very uncommon (1 in 100 or fewer), following Allan’s classification; analysis of variance (ANOVA) for race and sex differences, with p of 0.05 or less treated as significant.
- **Data type:** New field data: wax bite impressions taken from October to March (southern summer); the year is not given. The paper was received in July 2005 and published in 2006.

## Synopsis

### 1. What they did

Bite marks left at crime scenes, on victims’ skin or in things such as cheese, chocolate, apples or a sandwich, can help link a suspect to a crime or clear them. Every front tooth sits at a slight twist (rotation) in the jaw, and that twist shows up in the mark the tooth leaves. Until this study, no one had measured how common different rotations are, so experts weighed each feature of a bite mark by experience alone.

The researchers set out to develop a way to record and measure the rotation of each front tooth, and to class each rotation by how often it occurs in a population.

- Volunteers. They took bites from 300 volunteers (155 men and 145 women, aged 16 to 75) in the Bronkhorstspruit area of South Africa, chosen to match the age, race and sex make-up of the 1996 census. Denture wearers were included, because they could also be suspects.

- Bite impressions. Each volunteer bit into a folded wafer of pink dental wax on a labelled cardboard strip. About 25 people could be recorded in an hour.

- Models and photographs. Plaster models were cast from the wax bites and photographed through a stereomicroscope with a digital camera, with a measuring scale placed level with the biting edges of the teeth.

- Measuring. With image analysis software, they drew a curved line through the front teeth from canine to canine and measured the angle between that line and each tooth’s biting edge. Twists in one direction were recorded as positive, and in the other as negative.

- Classing. They used the spread of values in the sample to class each tooth’s rotation as common, uncommon or very uncommon, and tested for differences between race and sex groups.

### 2. What they found

- The method let them measure the rotation of each tooth in the upper and lower jaws.

- Rotations ranged widely. In 15 to 35 year olds, the extremes were −52° and +75° in the lower jaw and −80° and +50° in the upper jaw. In volunteers over 36, they were −39° and +35° in the lower jaw and −35° and +48° in the upper jaw.

- For each of the 12 front teeth, they set out which rotation values were common, uncommon and very uncommon in their sample (Tables 3 and 4). For example, an upper right canine turned more than 34° was very uncommon.

- Race made a significant difference for only two teeth (the upper right central incisor and the lower left central incisor). Sex made no significant difference for any tooth.

- A case example. A bite mark on a rape victim showed one clearly rotated lower incisor. Measured by this method, its rotation matched the suspect’s tooth and was uncommon in the research sample.

### 3. What they concluded

- Stereomicroscope photographs and image software gave an accurate, repeatable and user-friendly way to record, store and measure dental models. Digital images also save storage space and avoid broken models.

- Knowing how common each rotation is lets experts give each feature of a bite mark a weight, rather than relying on intuition and years of experience, which can be challenged in court. When a bite mark shows only a few teeth, one rare feature can count for as much as several common ones.

- The authors note that 300 volunteers is not enough to represent the whole population. Their results show the rotation values in this sample only and need to be followed by a much larger study, but they lay the groundwork for it.

- Dental features vary between countries and between age, race and sex groups, and a person’s teeth change over time. Dentures often carry unusual features, such as chipped or rotated teeth, that would count as uncommon in a bite mark case.

### 6. Other technologies, skills or innovations

- Wax bite wafers (pink dental modelling wax folded around a labelled cardboard strip), adapted from an earlier technique, warmed for denture wearers.

- Plaster models cast from the wax bites.

- Olympus stereomicroscope and Nikon digital camera, with fibre-optic lighting and a measuring scale in the same plane as the teeth.

- AnalySIS 3.0 image analysis software to draw the curved arch line and measure each tooth’s angle.

### 8. Implications for tracking (Original Wisdom's observations)

_These are Original Wisdom's observations, not the authors'._

- Reading a bite mark is a form of sign interpretation: like a track, the mark records the shape of what made it, and the expert works back from the mark to its maker.

- The paper’s central point carries over to tracks and signs: a feature is only useful for telling individuals apart if we know how common it is. Measuring how often a feature occurs gives a firmer basis than experience alone for judging how much weight it should carry.

## Cite this summary

Lawrence, K. 2026. Summary of: A Technique to Capture, Analyze, and Quantify Anterior Teeth Rotations for Application in Court Cases Involving Tooth Marks (Bernitz and van Heerden et al., 2006). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/2006-bernitz-van-heerden-technique-capture-analyze-quantify/