Malayalam

Malayalam is a Dravidian language of southern India, a language family also including Toda (see below) and Tamil. This group of languages provides many good examples of contrasts between dental and alveolar articulations. The example below shows six contrasting places of articulation for nasals, but Malayalam makes similar contrasts with plosives. Ladefoged & Maddieson (2008) suggest that while the dental stop is generally lamino-dental (they also use the term lamino-dentialveolar to indicate extensive tongue contact with the place of articulation) the nasal may even be interdental. Malayalam fits in with the general tendency that dental articulations for stops tend to be laminal, and alveolar articulations tend to be apical (a tendency extending to languages that have either a dental or an alveolar stop, but not both). Ladefoged & Maddieson (2008, p. 23) also discuss exceptions to this generalization

Ladefoged & Maddieson (2008) provide extensive discussion of dental and alveolar articulations in Toda (with palatograms and linguagrams) for both stops (p. 22) and sibilant fricatives (p. 156-160).
See SoWL demo of Toda fricatives.

Australian languages are another group of languages with considerable differentiation in the dental/alveolar region.
See SoWL demo of stops in Nunggubuyu and in Yanyuwa.
For Arrernte, palatograms and linguagrams are shown in Ladefoged & Maddieson (2008, p. 29) and Ladefoged, P. (2005, pp. 145-146).

kʌmmi ("shortage")	pʌn̪n̪i ("pig")	kʌnni ("first")	kʌɳɳi ("link in chain")	kʌɲɲi ("boiled rice and water")	mʌŋŋi   ("faded")

Note on the sonagrams: It is difficult to see differences during the nasals themselves, but differences in the transitions are quite clear.

Other examples: Malayalam Coronals

dental aspirated	retroflex aspirated
dental unaspirated	retroflex unaspirated