If these generalizations must be made, it's definately DO>dental. Osteopathic medical school is...Medical school... the bar intuitively is set higher. But, the numbers back that up as well...
Here is the most recent list I found around sdn:
Touro-NY: ?/30.8
Touro-Ca: 3.47/3.40/30.1
CCOM: 3.60/3.55/29.4
RVU: 3.60/3.57/28.33
DMU: 3.68/3.68/28.2
RowanSOM: 3.63/3.55/28
NYITCOM: 3.6/28
UNTHSC-TCOM: 3.59/3.51/28
COMP: 3.56/3.51/28
COMP-NW: 3.55/3.49/28
AZCOM: 3.51/3.44/28
LECOM-B: 3.50/3.40/28
UNECOM: 3.5+/28
NSU: 3.49/3.40/28
PCOM: 3.46/3.37/28 (2016)
TUNCOM: ?/28
MSUCOM: 3.57/27.57
OU-HCOM: 3.65/3.61/27.42
KCOM: 3.56/3.47/27
LECOM-E/SH: 3.48/3.35/27
ATSU-SOMA: 3.42/3.32/27 (2016)
PCOM-Ga: ?/27 (2015)
MUCOM: 3.57/3.49/26.28
OSU-COM: 3.61/3.54/26
KCUMB: 3.60/3.53/26
CUSOM: 3.55/3.23/26
WCU: 3.5/3.4/26
ACOM: 3.4/26
LMU: ?/26
PNWU: 3.40/3.31/25.76
VCOM-CC: 3.61/3.55/25 (2015)
VCOM-VC: 3.59/3.52/25 (2015)
WVSOM: 3.4/3.4/25
KYCOM: 3.5/3.4/24
As you can see, the bottom 1/3 has at least an avg gpa of 3.5, which is similar to dental school and an average mcat of 25, which is the average test takers score. The average DAT score is around 17 (correct me if im wrong) and accepted score is 19.
Now, the MCAT is a whole different monster than the DAT. For some people the DAT might be harder, but the passage based style of the mcat is what makes it so uniquely difficult to so many...
Also keep in mind that those numbers were for the BOTTOM 1/3. Even MD schools have similar lower stats for some schools in the midwest and south. As it turns out, DO schools follow the same trend, albeit a little lower. Schools like Rowan, CCOM, and Touro are way more competitive than most dental schools.
if you want to compare DO to dental, location location location matters. I could argue that Touro NY, stats wise, is probably more difficult to gain acceptance to than most NY dental schools except maybe nyu, columbia, and cornell