A recent decision from Québec’s Administrative Labour Tribunal (which governs workers compensation through its occupational health and safety division) got my attention.
In Gendron v. 123Dentiste Québec inc., 2026 QCTAT 2859, the Tribunal concluded that a dental hygienist’s severe bilateral thumb osteoarthritis (known medically as rhizarthrosis) constituted an occupational disease after nearly 30 years of repetitive clinical practice.
For Ontario dentists, the obvious question is whether the same type of claim could succeed here.
The answer is potentially yes, but the legal framework differs significantly. Ontario and Québec have different workers’ compensation legislation, different adjudicative bodies and different coverage rules. Understanding those differences is important for every dental practice owner.
The Québec Decision
The worker had practised as a full-time dental hygienist for approximately 29 years. She treated 6 to 8 patients daily. She spent most of her working day performing manual scaling, polishing and other repetitive clinical procedures.
At 49 years old, she developed severe pain at the base of her thumbs. Diagnostic imaging confirmed significant bilateral rhizarthrosis.
The Tribunal accepted her evidence describing years of repetitive pinch-grip movements, sustained thumb pressure, awkward wrist positioning and the manipulation of precise dental instruments in confined spaces. It also accepted her physician’s opinion that, although osteoarthritis is generally a degenerative condition associated with aging, the repetitive demands of her work had significantly contributed to the unusually early development of severe arthritis.
Although rhizarthrosis is not one of the occupational diseases that benefits from a statutory presumption under Québec law, the Tribunal concluded that her employment had played a significant and determinative role in the development of the disease. She was therefore entitled to occupational disease benefits.
Ontario’s Legal Framework Is Different
Ontario has its own laws and framework, which as I noted above differs from Québec’s.
In Ontario, we have the Workplace Safety and Insurance Act, 1997 (“WSIA”), which is administered by the Workplace Safety and Insurance Board (WSIB).
Like Québec, Ontario recognizes occupational diseases. However, many occupational diseases are not automatically presumed to be work-related. Instead, a worker must establish, through medical and factual evidence, that the disease arose out of and in the course of employment.
A dental hygienist alleging that repetitive clinical work caused or materially contributed to thumb arthritis would likely require evidence concerning:
- the medical diagnosis;
- the physical demands of the job;
- the frequency and duration of repetitive thumb movements;
- ergonomic risk factors;
- competing non-work causes; and
- expert medical evidence connecting the work duties to the condition.
The evidence accepted by the Québec Tribunal illustrates the type of evidence that would likely be persuasive in an Ontario proceeding as well.
An Important Question: Is Your Dental Practice Covered by WSIB?
One issue that surprises many Ontario dentists is that private dental practices are generally not required to register with the WSIB.
Unlike employers operating in mandatory industries such as construction, manufacturing and many industrial sectors, professional offices—including most dental practices—generally fall within a non-mandatory industry classification. As a result, participation in the WSIB system is typically voluntary unless another mandatory coverage requirement applies.
This distinction is extremely important.
If a dental practice has voluntarily registered with the WSIB, an eligible employee who develops an occupational disease may be entitled to claim benefits under the WSIA, assuming the medical and legal requirements are satisfied.
If the practice has not registered with the WSIB, the situation changes considerably. Generally speaking, employees of employers that are outside Ontario’s workers’ compensation system cannot claim WSIB benefits because the employer is not participating in the statutory insurance scheme. In those circumstances, the worker is ordinarily outside the WSIA compensation regime.
However, that does not necessarily mean the employer faces no legal exposure. One of the principal advantages of participating in Ontario’s workers’ compensation system is that covered employers generally receive protection from most civil lawsuits arising from workplace injuries. Employers that are not part of the WSIB system may not enjoy that same statutory protection. Depending on the facts, an injured employee may instead pursue a civil action alleging negligence, breach of the employer’s duty to provide a safe workplace, or other legal causes of action.
Every case depends on its particular facts, but the important point is that choosing not to participate in the WSIB system does not necessarily eliminate risk—it simply changes the legal framework within which that risk may arise.
Practical Lessons for Ontario Dentists
Whether or not your practice participates in the WSIB system, this decision serves as a reminder that dentistry and dental hygiene are physically demanding professions.
Dental hygienists spend countless hours performing repetitive scaling, polishing, instrumentation and suction while maintaining static postures and applying sustained pinch forces with their thumbs and fingers. Over many years, those cumulative stresses may contribute to musculoskeletal disorders affecting the hands, wrists, shoulders, neck and back.
As careers become longer and dental professionals remain in practice later in life, cumulative trauma claims may become increasingly common. Accordingly, practice owners should view ergonomics not simply as a workplace comfort issue but as an important risk management strategy.
Simple preventative measures may include selecting ergonomically designed instruments, encouraging micro-breaks between patients, rotating duties where practical, ensuring proper patient and operator positioning, providing ergonomic education and responding promptly when employees report discomfort.
Equally important is maintaining good documentation. If an employee reports thumb, wrist or hand pain, contemporaneous records regarding the complaint, any workplace assessment, modified duties, accommodation efforts and equipment changes may become important evidence should a claim later arise.
FYI: WSIB premiums are not expensive and they can give dentist employers and employees peace of mind should injury or accidents happen.
The Bottom Line
The Québec decision does not change Ontario law, but it provides a useful illustration of how tribunals analyze occupational disease claims involving repetitive clinical work.
An Ontario dental hygienist is not automatically entitled to WSIB benefits simply because arthritis develops during employment. The worker must establish the necessary medical and legal connection between the disease and the employment, and entitlement under the WSIA will also depend upon whether the employer is participating in Ontario’s workers’ compensation system.
For Ontario dentists, there are two practical questions worth asking: First, have you confirmed whether your practice is registered with the WSIB or whether registration is appropriate for your practice? Second, have you taken reasonable steps to reduce the ergonomic risks associated with repetitive clinical work?
The answers to those questions may have significant legal and financial consequences. A proactive approach to workplace ergonomics, careful documentation and a clear understanding of Ontario’s workers’ compensation framework remain among the best ways to reduce risk while supporting the long-term health of your team.
This article is intended for general information only and does not constitute legal advice. The application of Ontario’s Workplace Safety and Insurance Act, 1997, and related legal principles depends on the specific facts of each case. Dentists and practice owners should obtain legal advice regarding their particular circumstances.
