Short Answer: No
Long Answer: Most dentists will argue that a checkup every year is a wise thing to do and I would be hard pressed to disagree. But if a patient requested an exam every 18 months or even 24 months, I would not necessarily object so long as some criteria were met: they had a history of few or no cavities, they maintained good oral health and they did not start new prescription medications or have significant health changes. We are concerned with prescription medications because many of them cause xerostomia (dry mouth). A dry mouth doesn’t have the normal saliva flow which would otherwise buffer acids and wash away bacteria that cause decay. If a patient had some cavities every few years, had many teeth with fillings and other dental work or had a few health problems (this describes the majority of people) then an annual exam is appropriate. There has been some research looking for scientific evidence that frequent checkups by a dentist leads to fewer cavities. Recent reviews of these studies have shown that there is no specific recall frequency which is best for everyone. In fact, there is plenty of evidence to support the position that an exam frequency every 2 years does not result in a person having more cavities in the long run. And since dental decay takes anywhere from two to eight years to progress into an irreversible form, I can find little harm in waiting one to two years between dental exams. There are very rare situations when a person is at high risk of developing dental problems and they would need to be examined more frequently. But these situations are so rare that for the sake of answering the question, a checkup more frequently than once a year for the average person is not necessary.
[A Systematic Review of Dental Recall Intervals and Incidence of Dental Caries; The Journal of the American Dental Association May 2010 vol. 141 no. 5 527-539] [IS THERE A SCIENTIFIC BASIS FOR SIX-MONTHLY DENTAL EXAMINATIONS? The Lancet, Volume 310, Issue 8035, Pages 442 – 444, 27 August 1977 doi:10.1016/S0140-6736(77)90620-1 ]