Almost no one likes the dreaded six-month dental checkup -- except perhaps your dentist. But as unpleasant as all that scraping and drilling may be, it's a necessary evil to ensure healthy teeth.

For some people, investing is no different. You may hate checking up on your funds and monitoring your investment progress, but failing to do so could lead to nasty surprises down the road. After all, failing to meet your retirement goals is far worse than getting a cavity.

As June concludes, take this opportunity to perform a midyear fund portfolio checkup. It's a proactive way to uncover any potential hazards to your portfolio's health.

Open up and say ahhh ...
First up, check in with all of your existing mutual funds, and see whether anything about them has changed. New fund managers? Rising or falling expenses? A structural change, merger, or acquisition within your fund company?

Are the fund's holdings significantly different from what they were six months ago? If so, has management explained why it made such a substantial shift? Has the fund's turnover, number of holdings, or average market cap changed? Note anything that gives you pause.

Next, examine fund performance for the past six months. How have your funds done, given the market environment? Have they done well in absolute terms, or when compared to a relevant index, or even relative to other funds in their peer group?

If one of your funds has really tanked the past six months, don't panic and search for the "sell" button. Find out whether there's a reason for the slump; most fund companies provide quarterly commentary on how their funds performed. And always remember to focus more on long-term performance. Short-term performance is worth watching, but don't make hasty decisions based on a few months of good or bad returns.

That said, if your fund has fundamentally changed, and it's not the compelling buy it once was, don't be afraid to sell it. There's almost certainly a better outlet for your money.

Have you been flossing?
Next up, examine your portfolio's overall allocation. If one particular segment of the market has been doing well, your portfolio may now be overweighted in that area. Also, consider that once certain styles or areas do well for an extended period of time, they're more likely to be overpriced -- and to drop in the future. For example, international stocks, and especially emerging-market stocks, have enjoyed a tremendous run the past few years. But foreign markets may not continue to produce such stellar returns, and emerging markets could suffer a pullback. If your portfolio is especially heavy in foreign funds, consider reallocating some of that money into other, more attractively priced asset classes.

Similarly, everyone knows that growth stocks have been particularly unloved for the past seven or so years. Many of these stocks are now practically bargains compared to their value-oriented kin. Eventually, growth will rebound, and investors who position their portfolio accordingly stand to profit when it does. Think about upping your exposure to funds that will benefit when high-growth stocks like Oracle (NASDAQ:ORCL), Cisco Systems (NASDAQ:CSCO), and Google (NASDAQ:GOOG) really start to take off. Just keep in mind that old investing mantra -- buy low, sell high. You want to move your money from potentially overpriced stocks to underpriced ones.

Avoiding the drill
Taking a few hours every six months to review your mutual fund portfolio could be a real boon to your financial health. To avoid more serious problems in years ahead, take the time now to ensure that your investment program is on track. It's easy, it's painless, and you won't even have to lie about how often you floss.

Further Foolish fund fabulousness:

Now that you now how to perform a checkup on your portfolio, take the next step -- begin your search for high-performing funds. A free 30-day trial to the Fool's Champion Funds newsletter is a great place to start.

Fool contributor Amanda Kish lives in Rochester, N.Y., and does not own shares of any of the companies or funds mentioned herein. The Fool's disclosure policy is cavity-free.