# Teeth, jaws and facial growth after treatment in childhood

Source: https://onco.cc/technologies/rejuv-paed-teeth-and-face/  
OnCo record `rejuv-paed-teeth-and-face` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Treatment given while the teeth are forming can stop them forming. In the largest survey, survivors were three times more likely than siblings to report small teeth, three times more likely to report abnormal roots and nearly ten times more likely to report a dry mouth, and the risk was concentrated in children treated with alkylating drugs before the age of five.

## Summary

This is one of the most visible late effects and one of the least discussed, because it arrives years after the oncology clinic has closed the file and presents to a dentist who may not know the history.

The numbers come from 9,308 survivors diagnosed between 1970 and 1986 and 2,951 siblings in the Childhood Cancer Survivor Study, all reporting on their own oral and dental health. In multivariable analysis survivors were more likely to report microdontia, abnormally small teeth (odds ratio 3.0, 95 per cent confidence interval 2.4 to 3.8), hypodontia, teeth that never developed (1.7, 1.4 to 2.0), root abnormalities (3.0, 2.2 to 4.0), abnormal enamel (2.4, 2.0 to 2.9), the loss of six or more teeth (2.6, 1.9 to 3.6), severe gingivitis (1.2, 1.0 to 1.5) and xerostomia, a dry mouth (9.7, 4.8 to 19.7). Controlling for chemotherapy and socioeconomic factors, radiation exposure of 20 gray or more to the dentition was significantly associated with an increased risk of at least one dental abnormality. Alkylating agent therapy raised the risk of at least one anatomical or developmental dental abnormality in a dose-dependent way among survivors diagnosed before the age of five, with odds ratios of 1.7, 2.7 and 3.3 for alkylating agent scores of 1, 2 and 3. The authors concluded that patients receiving alkylating agents under the age of five "should be closely monitored".

Facial growth is the related problem. Radiotherapy to the head and neck in a young child slows growth of the irradiated bone, so the face can develop asymmetrically, the jaw can be small, and the bite does not meet. This is why orbital and head and neck radiotherapy in very young children is a central argument for proton therapy and for surgery where it can replace radiotherapy. The dry mouth that follows salivary gland irradiation then accelerates decay in teeth that are already abnormal, and the combination is what produces tooth loss in a person in their twenties.

What to do. Dental assessment before treatment, and then lifelong dental review with high-fluoride toothpaste, is the standard, and it is in the Children's Oncology Group guidelines. Orthodontic planning in a survivor needs the treatment history, because roots that are short or malformed limit what can safely be moved. Extraction from irradiated bone carries the risk of osteoradionecrosis, which is covered in the adult head and neck record in this front. Reconstruction of the jaw and orthognathic surgery exist for the worst outcomes and are done after growth is complete.

What comes back, and when: a tooth that never formed does not arrive later, and a root that stopped developing does not lengthen. This is a part of survivorship that is entirely about prevention, prosthetics and planning. The practical gap is funding: lifelong specialist dental care is not reliably paid for in most health systems, and the cost falls on the survivor.

## Fields

- Kind: Technology
- Status: established
- Last checked: 2026-10-02
- Tags: rejuvenation; survivorship; paediatric; late-effects; evidence:moderate
- Principle: Odontogenesis proceeds crown-first then root, under a timetable fixed by age, so an insult at a given age truncates whichever structures are then forming: enamel defects from an early insult, small crowns from one during crown formation, short or absent roots from one during root elongation. Cells of the dental papilla and Hertwig's epithelial root sheath divide actively and are therefore sensitive to alkylating agents and radiation. Craniofacial bones grow at sutures and synchondroses that irradiation damages directly, producing asymmetry and hypoplasia in proportion to dose and inversely to age at exposure.
- Strengths: Risk is predictable from age at treatment and exposure, so monitoring can be targeted; Prevention with fluoride and regular review is cheap and effective; Prosthetic and orthodontic solutions exist for most of the damage
- Limitations: The developmental damage itself cannot be reversed; The survey evidence is self-reported rather than examined by a dentist; Lifelong specialist dental care is rarely funded

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Microdontia
- Impact of radiation and chemotherapy on risk of dental abnormalities (CCSS) (Cancer 2009): https://doi.org/10.1002/cncr.24670
- Children's Oncology Group: Long-Term Follow-Up Guidelines and Health Links: https://childrensoncologygroup.org/survivorship/
- Clinical ascertainment of health outcomes among adults treated for childhood cancer (SJLIFE) (JAMA 2013): https://doi.org/10.1001/jama.2013.6296

## Connected records

- trials: [Childhood Cancer Survivor Study (CCSS)](https://onco.cc/trials/ccss/)
- companies: [Children's Oncology Group (COG)](https://onco.cc/companies/childrens-oncology-group/)
- cancers: [Acute lymphoblastic leukaemia](https://onco.cc/cancers/all-leukemia/), [Childhood cancers (all types)](https://onco.cc/cancers/childhood-cancers/), [Medulloblastoma](https://onco.cc/cancers/medulloblastoma/), [Neuroblastoma (paediatric)](https://onco.cc/cancers/neuroblastoma/), [Retinoblastoma](https://onco.cc/cancers/retinoblastoma/), [Rhabdomyosarcoma](https://onco.cc/cancers/rhabdomyosarcoma/)
- fronts: [Recovery & Rejuvenation](https://onco.cc/fronts/rejuvenation/), [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- technologies: [Dry mouth, teeth and taste after head and neck radiotherapy](https://onco.cc/technologies/dry-mouth-teeth-after-head-neck-radiotherapy/), [How much illness childhood cancer survivors carry, and at what age](https://onco.cc/technologies/rejuv-paed-chronic-disease-burden/), [Hyperbaric oxygen for late radiation injury](https://onco.cc/technologies/hyperbaric-oxygen-radiation-injury/), [Proton therapy](https://onco.cc/technologies/proton-therapy/), [The Children's Oncology Group Long-Term Follow-Up Guidelines](https://onco.cc/technologies/rejuv-paed-cog-ltfu-guidelines/)
- terms: [Late effects and survivorship toxicity](https://onco.cc/terms/late-effects/), [Radiotherapy](https://onco.cc/terms/radiotherapy/)
- drugs: [Cyclophosphamide](https://onco.cc/drugs/cyclophosphamide/), [Ifosfamide](https://onco.cc/drugs/ifosfamide/)
- bottlenecks: [Survivorship and late effects are neglected](https://onco.cc/bottlenecks/b-survivorship/), [Toxicity and quality of life are undervalued](https://onco.cc/bottlenecks/b-toxicity-qol/)

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