Notre Dame will face No. 1 Fredericktown in the finals at 6 p.m. on Friday.
The Bulldogs (17-8), seeded second, scored their only basket with 7 seconds remaining in the first quarter. Notre Dame had few looks from leading scorer Kristain Burger in the quarter, and settled for outside shots before Burger broke the scoring silence.
Dexter led 3-2 after one quarter.
"I don't think either team was real happy with it," Notre Dame coach Jerry Grim said. "Sometimes that happens. I know that the girls were nervous, more nervous than any other game this season."
Dexter's biggest lead in the half was four points, which it had twice in the second quarter.
Notre Dame took its first lead at 11-9 and led by as many as 15-9 in the second quarter.
"They're the same as we are," Grim said. "They put their pants on one leg at a time, the same way we do. All they had to do was realize that, and take care of the ball."
Dexter senior Haylee Finch hit a pair of 3-pointers in the opening half to help the Bearcats pull even, 17-17, at halftime. The Bearcats missed several easy chances in the opening half.
"I had a plan in the first half just to throw every defense we could at them, and it worked," Dexter coach Gavin Miller said. "I guarantee you we missed five layups the first quarter. When you present those to your team you have to take advantage of your opportunities."
Burger, who averages 19 points a game, took over in the third quarter for the Bulldogs. The 5-foot-11 senior scored the first six points of the quarter for Notre Dame, and had nine points in the period.
An 8-0 run gave the Bulldogs a 29-20 lead early in the third, and Notre Dame pushed the lead to 10 points twice in the quarter.
Miller said his team came out nervous in the opening half, and that only got worse in the second half.
"I thought they increased their nervousness and tension," he said. "They just did not play relaxed."
Still, the Bearcats were able to chip away at the lead and cut the deficit to 34-29 after three quarters. The rally did not last long as Dexter fell behind 41-29 early in the quarter on a 3-pointer from Meridith Medlin.
Medlin, also a senior, came up big in the fourth quarter with nine points.
From the free throw line, Medlin was 6-for-6 down the stretch.
"That's one thing -- we have a good combination of senior leadership and youth," Grim said. "Our young kids have a lot of talent, but they need those seniors to gel."
Despite the performance from the line, Dexter was able to cut the lead to 47-44 on a basket from Jill Temples with less than 2 minutes remaining.
Dexter had the ball down 47-44 with less than a minute remaining but turned it over.
"There at the end, it was anyone's game," Grim said. "You just have to count on who's on the floor."
Notre Dame hit five of six free throws in the final minute for the final margin. Overall, Notre Dame hit 14 of 19 free throws, while Dexter managed just six of 13.
"The free throws were big for us," Grim said. "Last year, I think as a team we were 40-something percent or 50 percent, and this year we're right at 70 percent. That's a big improvement."
Burger led the Bulldogs with 20 points, Medlin added 13 and sophomore Alex Fowler had 10 points.
Pirates bow out
The Bulldogs will have to pull the upset in the championship Friday after top-seeded Fredericktown slipped past No. 4 Perryville 46-44. Betsy Royer hit a layup with 3 seconds remaining for the win.
Perryville seemed to have the game in hand, leading 44-41 with less than 2 minutes remaining and with the ball. The Blackcats were in foul mode, but Perryville turned the ball over with 1:18 left and Johnna Tinnin converted a three-point play on the other end to tie the score 44-44.
"We just had too many turnovers," Perryville coach Vicki Lohmann said.
The Pirates (16-10) held a 38-30 lead heading into the fourth quarter, but managed to turn the ball over on its first six possessions of the fourth quarter. Perryville had nine turnovers in all in the final period, but still did not trail until the final basket.
Fredericktown (24-2) used an 8-0 run to tie the score 38-38 just 2 minutes into the quarter. Perryville led the rest of the quarter until Fredericktown scored the final five points.
Royer, a 6-0 senior, had been quiet offensively for much of the game. Royer scored six points in the fourth quarter, though, and was able to get free for the final hoop. Overall, Royer led the Blackcats with 14 points and added eight blocked shots.
"We made sure to bump the big girl and keep in contact with her, and it worked for the majority of the game," Lohmann said. "I told the girls at the timeout, anything but inside."
Perryville was unable to get a shot off before the buzzer.
Alyssa Bauwens led the Pirates with 16 points, 11 coming in the third quarter. Kendra Schilli added 11 points and Nicole Gremaud had nine on three 3-pointers.
The Pirates have just one senior on their roster along with four sophomores, three juniors and a freshman.
"My starting lineup is returning," Lohmann said. "That doesn't necessarily mean they will be my starting lineup next year. I've got a solid group coming back."
Notre Dame 52, Dexter 44
NOTRE DAME (52) -- Kristain Burger 20, Meridith Medlin 13, Alex Fowler 10, Paige Schumer 4, Emily Brumitt 2, Brooke Beussink 1, Claudia Brauss 2. FG 17, FT 14-19, F 13 (3-pointers: Fowler 2, Medlin 2. Fouled out: none)
DEXTER (44) -- Haylee Finch 13, Jill Temples 10, Katelyn Heil 10, Amanda Dooley 6, Ashlee Taylor 4, Cathryn Heil 1. FG 17, FT 6-13, F 18 (3-pointers: Finch 3, Temples 1. Fouled out: K. Heil)
Fredericktown 46, Perryville 44
PERRYVILLE (44) -- Alyssa Bauwens 16, Kendra Schilli 11, Nicole Gremaud 9, Ava Johnson 6, Kim Miesner 2. FG 18, FT 5-8, F 13 (3-pointers: Gremaud 3. Fouled out: none)
FREDERICKTOWN (46) -- Betsy Royer 14, Tricia Ward 12, Nicki Settlemoir 9, Courtney Kemp 7, Johnna Tinnin 4. FG 18, FT 7-15, F 10 (3-pointers: Ward 2, Kemp 1. Fouled out: none)