DENTAL students at Scotland's flagship school risk failing their final year due to a shortage of patients on whom to practise vital treatments.

Aberdeen Dental School has twice written to local dentists appealing for them to refer patients to alleviate a potential training crisis at the multimillion-pound facility. Undergraduates are required to carry out a certain number of procedures, such as root canal treatments and fillings, in order to achieve enough points to qualify.

The procedures, supervised by professional dentists at the teaching clinics, are offered free of charge to members of the public. However, a lack of volunteers is putting students' degrees at risk.

Just week ago students at ­Glasgow University's dental school raised similar concerns about a shortage of available patients. Those students who have not completed enough procedures at the end of their studies cannot qualify as professional dentists.

In a letter dated January 9, Aberdeen Dental School's department of paediatric dentistry wrote to local dentists requesting child referrals. This was followed up on ­February 26 by a letter saying the school needed adults requiring work on crowns, bridges and dentures, as well as "children in need of all forms of restorative work".

It comes four years after the new £17.7 million centre was opened by First Minister Alex Salmond, who promised it would deliver a significant increase in the number of NHS dentists.

The north-east traditionally struggled to recruit enough NHS dentists, but some practitioners in the region now fear efforts to turn around the problem with taxpayer subsidies have flooded the area with new practices. Figures show that between 2002-2013, the number of dentists in Grampian increased by 86%, more than double the rate of growth for Scotland as a whole.

Much of the growth has been driven by Scottish Dental Access Initiative (SDAI), which saw more than £3 million in Government grants handed out to 19 Grampian dental practices - 16 of them new - between 2008 and 2012.

Ross McLelland, a dentist in Aberdeen, said he noticed business becoming "thin on the ground" and blames mismanagement of the scheme for saturating the market. He said: "The ­shortage of work for the students is just another symptom of how much overcapacity there now is in Grampian. It must be very worrying for the students and staff if there is not enough clinical work for training purposes."

NHS Grampian has now discontinued SDAI grants in Aberdeen and Moray, and is phasing them out in Aberdeenshire.

Pat Kilpatrick, director of the British Dental Association in Scotland, said: "Dentists are effectively competing for patients as it is, so it's inevitable that there are fewer patients to go round and they're not going to be referring them away to the dental school."

There are 192 dental students due to graduate this summer from Scotland's three dental schools.

An NHS Grampian spokesman said the boom in dentists had cut waiting lists from more than 30,000 to about 200, but added: "Grampian still has registration levels that are 17% below the national average, with the lowest adult registrations in Scotland".

A spokesman for the Scottish Government said: "NHS Grampian has made steady progress in terms of registration with NHS practitioners but is drawing its SDAI programme to a close."