3M has filed its third pat­ent in­fringe­ment law­suit in Germany in 16 months in re­gard to its den­tal tech­nol­o­gy.

3M Co. sued Ger­man den­tal firm Den­tal Direkt GmbH over the week­end. The law­suit, which was filed in Dusseldorf, Germany, said Den­tal Direkt was not licensed to use 3M’s tooth-color-match­ing tech­nol­o­gy, which is em­ployed world­wide by den­tists and la­bora­to­ries mak­ing ce­ra­mic den­tal res­to­ra­tions.

Of­fi­cials of Den­tal Direkt, which is based in Spenge, Germany, could not be reached for com­ment.

The law­suit said Den­tal Direkt il­le­gal­ly used 3M’s tech­nol­o­gy when mak­ing zir­co­nia CAD/CAM block pro­ducts that are sold un­der the brand names DD Bio Z and DD Bio ZX trans­lu­cent. The com­pany also is ac­cused of il­le­gal­ly using 3M’s tech­nol­o­gy in col­or­ing li­quids sold un­der the brands DD Bio Z color clas­sic and DD Bio ZX mon­o­lith Zero.

3M’s den­tal di­vi­sion, called 3M ESPE, is con­sid­ered an in­dus­try lead­er in the world of ce­ra­mic den­tal im­plants, crowns and fill­ings. It has worked to im­prove colorations and dra­mat­i­cal­ly speed up the time in which den­tal labs and den­tists can make crowns and oth­er im­plants for pa­tients.

In Au­gust, 3M un­veiled a new oral scan­ner de­signed to quick­ly cre­ate three-di­men­sion­al im­ag­es of pa­tients’ teeth so re­al­is­tic-look­ing im­plants could be made more quick­ly.

3M of­fi­cials said the Maplewood-based con­glom­er­ate li­censes its tech­nolo­gies to much of the den­tal in­dus­try and re­mains open to “licens­ing this tech­nol­o­gy to oth­er in­ter­est­ed par­ties.”

In 2013, 3M filed two pat­ent in­fringe­ment law­suits against den­tal-prod­uct firms in Dusseldorf.

The law­suit against Metoxit AG alleged in­fringe­ment re­gard­ing col­or­ing li­quids or zir­co­nia blocks sold un­der the brands Z-CAD FlowPen, Z-CAD Li­quid HD and Z-CAD. 3M has set­tled the oth­er law­suit, against White Peaks Den­tal Systems GmbH & Co. KG.

3M of­fi­cials have said in the past they must en­force the pa­tents 3M re­ceives to pro­tect its grow­ing annu­al re­search and de­vel­op­ment ef­fort.

In a meet­ing with ana­lysts last week, CEO Inge Thu­lin not­ed that 3M is com­mit­ted to grow­ing its den­tal and health care busi­ness — one of its fast­est-grow­ing seg­ments — and strong­ly com­mit­ted to in­creas­ing its R&D com­mit­ments.

He said 3M will in­crease its R&D spend­ing on new pro­ducts from 5.6 percent of sales in 2013 to 6 percent of annu­al sales by 2017. As a re­sult, R&D spend­ing will jump from $1.5 bil­lion in 2013 to about $1.9 bil­lion by 2017.