Using lower wisdom teeth developmental stages determined from panoramic x-rays to calculate age

Recently, two articles have been published on this site regarding forensic age estimation using wisdom teeth and using panoramic x-rays of lower wisdom teeth to legally prove if someone is older than 18 years and 21 years. In the first study the age of a person was determined from wisdom teeth x-rays based on four stages of the emergence of a wisdom tooth using both upper and lower wisdom teeth. In the second study the age of a person was determined from wisdom teeth x-rays based on the presence and extension of periodontal space (periodontal ligament) and also the presence of root pulp of lower wisdom teeth based on four stages. In order to explore more precise predictions of the age of a person using wisdom teeth x-rays, a study was conducted using several radiological measurable findings in an article titled “Predictive values derived from lower wisdom teeth developmental stages on orthopantomograms to calculate the chronological age in adolescence and young adults as a prerequisite to obtain age-adjusted informed patient consent prior to elective surgical procedures in young patients with incomplete or mismatched personal data,” by Friedrich et al. (GMS Interdiscip. Plast. Reconstr. Surg. DGPW, vol. 5, doc. 23, pp. 1-32, 2016, Published December 6, 2016).

The authors in the Friedrich et al. study were well read and familiar with previous work by Olze et al. and others. Specifically, in the study the authors used four radiological criteria of lower wisdom teeth: 1.) presence and extension of periodontal space, 2.) alveolar (periodontal) bone loss, 3.) emergence of wisdom tooth and 4.) root development and tooth mineralization. It is noted that (1) was the same criteria as discussed in Olze et al. in “Assessment of the radiographic visibility of the periodontal ligament in the lower third molars for the purpose of forensic age estimation in living individuals,” International Journal of Legal Medicine, vol. 124, pp. 445–448, 2010, and as discussed in one of the prior articles on this site as mentioned above, although a slight modification to (1) was performed to account for the periodontal space which is a fine radio translucent structure delineating the dental root. Further it is noted that (3) was the same criteria as discussed in Ozle et al. in “Studies of the Chronological Course of Wisdom Tooth Eruption in a Black African Population,” Journal of Forensic Sciences, vol. 52, no. 5, pp. 1161-1163, Sep. 2007, and as discussed in one of the prior articles on this site as mentioned above, although an additional stage was added to account for elongation and the most cranial part of the wisdom tooth above the occlusal plane. In the article the authors present some very nice pictorial illustrations side by side of x-rays of the same in a wisdom tooth to illustrate all the criteria they explore. In the study the authors looked at 1,895 panoramic x-rays or orthopantomograms from 935 females and 960 males after accounting for their inclusion criteria (a history of trauma, neoplasia, or maxillofacial deformity). The authors made special attention to include roughly 100 people per each and every single age from 15 to 24 years old for both genders as a lack of doing so had been noted in other earlier studies as an issue.

The authors performed statistical analysis on their results and calculated receiver operating characteristics (ROC) curves and hierarchical models. The authors also performed a Classification And Regression Tree (CART) analysis in order to predict the status of age. No statistical differences were found when accounting for either the lower right or the lower left wisdom tooth. The authors noted that looking at
alveolar (periodontal) bone loss provided no statistically significant results showing a predictability of age depending on wisdom teeth alveolar bone height. With respect to emergence of wisdom teeth the authors noted females are about 0.7 years ahead in the development of stages 1 and 2 when compared to males, but females are 0.5 years behind in the development of stages 3, 4 and 5 when compared to male. Regarding wisdom tooth growth in the occlusal plane, 50% growth was achieved at ages 20 and 21 respectively for males and females. Regarding root development and tooth mineralization, females are roughly 0.6 years ahead in the most of development stages when compared to males. However, females complete root development about 1.5 years later than males. Regarding the presence and extension of the periodontal space, the authors feel an age of at least 18 years is to be expected in individuals that have reached stages 2 and 3 of Olze et al. which were modified in this study (Olze et al. in contrast said if an individual reached stages 2 and 3, the age can be stated to be over 21 years of age, so the current study is more restrictive).

From the hierarchical multivariate analyses the authors performed they state

“Individuals, who are at least 20 years of age, are reliably predicted as adult…18 years of age or more. On the other hand, the calculation cannot clearly distinguish in a person with a true age of 18 years whether the individual is just below or above this age limit…the analysis cannot substitute the knowledge of an individual calendrical date of birth. Nevertheless, the calculation allows a more or less precise calculation of individuals who are about 18 years of age.”

wisdom teeth orthopantomogram xray - Using lower wisdom teeth developmental stages determined from panoramic x-rays to calculate age
The above image is from Fig. 3 of Friedrich et al. and has a Creative Commons license.

To summarize their findings, the authors feel the periodontal space is a valuable parameter to help determine age based on x-rays of lower wisdom teeth. The authors feel there is no close relationship between age and alveolar bone loss in the wisdom tooth region and thus looking at alveolar bone loss in x-rays of lower wisdom teeth will not help determine age. The authors feel this may occur due to transient bone loss occurring during the emergence of wisdom teeth. Regarding using root development and tooth mineralization to predict age the authors noted different staging methods have been applied in the past and the best method is likely from Demirjian et al. in the article titled, “A new system of dental age assessment,” Human Biolology, vol. 45, pp. 211–227, 1973, to evaluate age based on wisdom teeth.  The authors also point out that gender has an impact on radiologically assessed root formation and thus gender must be taken into account when predicting age based on root formation of wisdom teeth in x-rays. The authors noted there are many studies that have explored the emergence of wisdom teeth to estimate age. They are careful to note that these prior studies have shown wisdom tooth emergence has considerable ethnic variations (as further discussed on this site in the post forensic age estimation using wisdom teeth) and thus ethnicity must be considered when calculating age based on wisdom teeth emergence. In their study the authors did not explore any ethnic variations as all the panoramic x-rays came from a German population. The bottom line is the authors feel a combined analysis of lower wisdom teeth measurements can improve age estimation. The authors provide a formula to calculate the probability of age being 18 years or more if it has been estimated to be between 15 and 24 years but caution that it has limitations and therefore encourage additional studies exploring this age calculation approach in varying ethnic groups.

Now exploring results from Friedrich et al. with results from Ozle et al. in the studies 1.) Ozle et al., “Studies of the Chronological Course of Wisdom Tooth Eruption in a Black African Population,” Journal of Forensic Sciences, vol. 52, no. 5, pp. 1161-1163, Sep. 2007, 2.) Ozle et al., “Studies of the chronological course of wisdom tooth eruption in a German population,” Journal of Forensic and Legal Medicine, vol. 15, pp. 426–429, 2008, 3.) Ozle et al., “Studies of the chronological course of wisdom tooth eruption in a Japanese population,” Forensic Science International, vol. 174, pp. 203–206, 2008, and 4) Schmeling and Olze et al. “Dental Age Estimation Based on Third Molar Eruption in First Nations People of Canada,” Journal of Forensic Odonto-Stomatology, vol. 28, no. 1, pp. 32-38, 2010, visuals are generated by this website’s author and presented below generated using Minitab 18 (where the two lower wisdom teeth are combined into an average for stages A and B in the studies by Ozle et al.). Note that the data used specifically pertains to only the emergence of lower wisdom teeth (where German A refers to from the study by Ozle et al. and German B refers to from the study by Friedrich et al.)

mean age when lower widsom teeth not emerged and occusal surfaced covered by bone 1024x322 - Using lower wisdom teeth developmental stages determined from panoramic x-rays to calculate age
mean age when lower widsom teeth partially erupted partially covered bone 1024x293 - Using lower wisdom teeth developmental stages determined from panoramic x-rays to calculate age

These figures help further illustrate the conclusion by Friedrich et al. that
additional studies exploring their age calculation approach using varying ethnic groups are needed.

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