The Isle of Man High Court has found that psychiatric damage allegedly caused by negligent dental treatment passed the material contribution causation test.

In a longstanding claim it was alleged that failure to diagnose and treat periodontal disease and negligently carrying out orthodontic work despite the presence of advanced chronic periodontitis caused the claimant's psychiatric injuries, notwithstanding that she already suffered recurrent depression at the time of the negligent dentistry. The defendant parties admitted liability but disputed causation and quantum.

After hearing detailed lay and expert evidence, the Isle of Man High Court found that the lack of diagnosis of periodontal disease itself led to the lack of timely treatment, which had then worsened the condition of the claimant's teeth. In order to assess the extent of the psychiatric illness caused by the admitted negligence, the court heard expert psychiatric evidence. The experts agreed that the claimant's depression was a condition that existed before the dental work. The court accepted expert evidence that stressful life events can provoke depressive symptoms, but found that there was no significant link between the early recurrence of the claimant's mental health problems and the dental work. The contribution of the dental negligence to the depression in the early period was therefore deemed modest, perhaps as low as 20%.

However, the High Court accepted that from 2006 onwards, the dental negligence had worsened the claimant's depression rather than simply accelerating episodes of recurrence. The court found that the effect of the negligent dentistry was that after 2006, the claimant's episodes of depression became longer and more disabling, developing into a chronic nature.

The court concluded that in terms of causation, even though the claimant would have suffered a recurrence of depression, such an episode would not have lasted from 2006 to 2011. It therefore found that the index event made the claimant's depression worse. The court also found that although the claimant was a vulnerable individual, it was unlikely that she would have developed body dysmorphic disorder without the negligence. The disorder was found to be a significant part of the overall psychological difficulties encountered by the claimant, preventing her from enjoying life to the full. The high bailiff stated:

"When superimposing the impact of the body dysmorphophobia on to the 20% contribution of the index event to the worsened depression, it appears to me that the significance of the index event moves up in percentage terms in respect of the overall debilitation of the Claimant from 2006 to something around the half-way mark."

The court found that it was difficult to separate the debilitating effects of depression and the claimant's body dysmorphophobia, describing it as "an indivisible injury". Accordingly, the court applied a broad-brush approach and looked at the whole psychiatric disability that the claimant suffered since the dental negligence in the light of her pre-existing vulnerability and other stressors. The high bailiff stated, that taking all matters in the round:

"the significance of the index event is that it contributed in about equal measure to the overall debilitation with that of a combination of the pre-existing recurrent depression and the other negative life events in worsening the overall psychiatric picture."

The court accepted that a significant reduction should be made in the compensatory sum to allow for the causative contribution of the life events to the claimant's depressive illness and for the pre-existing nature of that depression.

Total general and special damages exceeding £69,000 were awarded to the claimant. Her death during the lengthy legal action was not connected with the cause of action. The claim was issued in August 2009 and the claimant died in February 2015. The case came to trial in April 2015 with the judgment in June 2015. In terms of the delay between issue of proceedings and trial, the court commented that the case was not a model for how such proceedings should be dealt with in terms of expedition.

For further information on this topic please contact John T Aycock at M&P Legal by telephone (+44 1624 695800) or email ( The M&P Legal website can be accessed at

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