By Jesse Kane

Maintaining papilla between adjacent implants is extremely difficult. Tarnow’s original rule falls apart a little bit when you have two implants next to each other. Long story short is you can expect around 3mm of soft tissue height above the crest of bone when you are dealing with two adjacent implants.

But there are a two major caveats:

1) Implants cant be closer than 2.5mm from each other

2)You must account for potential bone loss between implants and the loss of the scalloped architecture of bone that exists between natural teeth.

The original Tarnow study (1992) showed that when the distance from the contact point between NATURAL TEETH to thebone crest was ≤ 5 mm, the interproximal papilla was ALWAYS PRESENT.

In Tarnow’s subsequent paper titled,  “The effect of inter-implant distance on the height of inter-implant bone crest.” (2000) the same investigators looked at the horizontal distance between implants and found that in addition to the vertical dimension between bone and contact point there was also a lateral component when two implants are involved.

They concluded that there should be a minimum 3mm of bone between implants for there to ever be substantial papilla fill. Then in 2003 the same authors investigated the “Vertical distance from the crest of bone to the height of the interproximalpapilla between adjacent implants.” Basically this was the analogous study to his original 1992 study but between two implants instead of between two teeth.

Their conclusion was that clinicians should proceed with GREAT CAUTION when placing two implants adjacent to eachother in the esthetic zone. In most cases, an average of 3.4mm of soft tissue can be expected to form over the interimplant crest of bone. 3.4mm but this varies from 2-4mm.

This is compounded by a very very important fact that bone tends to lose its natural scallop between implants. This little scallop or peak of bone is what supports the papilla when natural teeth are present.

In an excellent study from 2019 by Camila Souza titled “Factors Influencing the Presence of Papilla between AdjacentImplants and between a Tooth and an Implant” investigators found that between adjacent implants, even when the vertical distance from the crest of bone to contact point was <5mm, 48.7% did not present papilla formation. A couple of studies have re-invetsiaged these metrics and one in particular stands out to me from 2011 titled, “Effect of Interimplant distance (2 and 3 mm) on the height of interimplant bonecrest: a histomorphometric evaluation.”

This time they used platform switched implants and found that there was maybe 2mm between implants is ok for papilla formation WHEN USING PLATFORM SWITCHED IMPLANTS. Gastaldo et al. in 2004 sort of summed all of this up in “Effect of the Vertical and Horizontal Distance Between Implants and Between a Tooth and an Implant on the Incidence of Interproximal Papilla”.

Their conclusion was that In addition to the vertical distance, the horizontal distancebetween adjacent implants when smaller than 3 mm determined the absence of interproximal papilla, independent ofthe vertical distance.

This dilemma is what spurred some of the lateral socket shield AKA partial root resection therapy techniques. The idea is maybe if you keep a little sliver of tooth root present next to one of the implants you won’t lose as much bone and the papilla will stick around. This is MUCH debated but I've seen some really impressive cases and some really impressive failures too… Joeseph Kan gave an awesome lecture on this at the 2021 AO meeting.