Dental issues sideline Twins center fielder Byron Buxton

FORT MYERS, FLA. – Byron Buxton was eating a steak dinner Monday night when he encountered a problem that has kept him out of the Twins' lineup ever since.

A tooth broke.

In the days since, the Twins center fielder has undergone root canal and had a crown placed over the old tooth, relatively routine procedures that have kept him in a dental chair instead of center field.

Which is fine with his manager.

"We wanted to make sure that it got done now, so that it wasn't something that wasn't going to linger and potentially have to be worked on close to Opening Day, or even after," Rocco Baldelli said. "Buck's going to be fine. I exchanged some calls and texts with him. … We're going to see him back out on the field very soon."

Three weeks remain until the Twins' opener in Milwaukee, and Buxton's dental emergency has allowed the Twins to give more at-bats to several of the candidates for backup outfield spots. Keon Broxton, Gilberto Celestino and on Thursday, right fielder Max Kepler have started in Buxton's normal position — though oddly, none collected a hit while doing so.

MLB will use its new control over minor league baseball this season to experiment with potential rule changes, with each level utilizing a different change. In Class AAA, for instance, bases will be 18 inches square rather than the current 15-inch size, in an effort to reduce collisions.

At Class AA, teams will be required to station at least four infielders with both feet on the infield dirt, to reduce the number of extreme shifts and increase batting average on balls in play.

High-Class A leagues will require pitchers to step off the rubber before throwing to any base, a change that will encourage stolen-base attempts.

The three low-Class A leagues will all have different trial rules: One will limit pitchers to two pickoff throws or "step-offs" per plate appearance with a runner on base; one will use an automated system to assist umpires with calling balls and strikes; and one will institute strict time limits between pitches, innings and pitching changes.

Alex Kirilloff has gotten more playing time than any other Twin this spring as he tries to demonstrate that he's ready to be the team's starting left fielder.

He probably hasn't accomplished that yet, not with a .188 batting average (3-for-16) and five strikeouts, but those hiccups are easy to forget when a rookie smacks a curveball 410 feet to straightaway center, as Kirilloff did Thursday against Red Sox lefthander Eduardo Rodriguez.

"Any time a ball is clanging off the batter's eye, it kind of makes everyone around the stadium, including the dugout, look around and nod in approval," Baldelli said.

"It's just a taste of what AK can do, but that's the kind of offensive potential that you're talking about.

… I wouldn't even call it potential. He just hasn't had the opportunities yet at the major league level."

Kirilloff played first base again Thursday, where he's been stationed about half the time in order to give backup outfield candidates more playing time.

Andrelton Simmons was in the Twins' dugout during a game for the first time Thursday, observing and learning the Twins' defensive signals and shifts.

It's the final step before Simmons, who was delayed from spring camp by two weeks, plays his first Grapefruit League game for his new team, expected to happen Friday.

"We thought it was a good idea to get him in the dugout for a couple of innings to talk with [third-base and infield coach] Tony [Diaz] and see how he operates, so he's not figuring it out on the fly when he's out there playing," Baldelli said.

"I hope he got a good amount out of it."

• Kepler played only three innings after fouling a ball off his thigh, an injury that's not considered serious. "I'll bet he has a pretty good bruise that he's going to wake up with, but I would expect him to be fine," Baldelli said. He noted that on the next pitch after being hurt, he hit a ball that was caught on the warning track in right field. "I thought he actually homered after he fouled the ball off his leg," Baldelli said, "but he hit it into the teeth of the wind."

• A sore lower back has prevented Caleb Thielbar from appearing in a game, but that will change soon. The veteran lefthander has thrown a couple of sessions of live batting practice, and "I would say there have been no setbacks since the original injury," Baldelli said. "He's throwing it really well. He's letting it loose. I don't think there's anything inhibiting him at this point."