How do I complete the "A Brilliant Smile" triumph?
To brush your teeth, you'll need a toothbrush. In order to get a toothbrush, you'll need to finish a quest chain that only starts after you've completed Eva's quests and obtained a Festival of the Lost mask.
- Speak to Eva in the Tower and complete her quests
- Complete a run of the Haunted Forest
- Obtain one of the Festival of the Lost Masks (has icon of Master Rahool)
- Speak to Eris Morn, located at the Moon
- In order to start the quest chain, you need to have your Mask equipped.
- You should receive the quest item, Box of Raisins
- Speak to Spider, located at the Tangled Shore
- Complete the quest Even Handed, which requires 12 Fallen, Scorn, Hive and Cabal enemy kills on the Tangled Shore
- You should receive the quest item, Winged Chew
- Speak to Anastasia Bray, located on on Mars
- Complete the quest Armed to the Teeth, which requires 10 Kinetic, Energy, and Power weapon kills on enemies in Mars
- You should receive the quest item, Unchocolate
- Speak to Asher Mir, located on Io
- Complete the quest Precisely, which requires 10 precision final blows on both Vex and Taken on Io
- You should receive the quest item, Piece of Celery
- Speak to Brother Vance, located on Mercury
- Complete the quest In Your Element, which requires 10 Arc, Solar, and Void kills in Mercury
- You should receive the quest item, Splice Drops
- Speak to Failsafe, located on Nessus
- Complete the quest Touched by the Light, which requires 5 Fallen, Vex, and Cabal kills on Nessus using abilities.
- You should receive the quest item, Salted Sweets
- Speak to Devrim Kay, located at the EDZ
- Complete the quest Foregone Conclusions, which requires 5 Fallen, Cabal, and Taken finishers in the EDZ
- You should receive the quest item, Sour Engram
- Speak to Petra Venj, located in the Dreaming City
- Complete the quest The Best of My Abilities, which requires 5 melee and grenade ability kills, and 10 super kills in the Dreaming City
- You should receive the quest item, Sugary Engram
- Speak to Sloane, located on Titan
- Complete the quest Not In Our House, which requires an undisclosed amount of kills in the Solarium, Festering Halls, and Arboretum in Titan
- Each kill seems to reward 3.5% progress in the Solarium, and 7% in the Festering Halls and Arboretum
- You should receive the quest item, Void Fizz
- Return back to the Moon and speak to Eris Morn
- Complete the quest The Dance of My People, by dancing for Eris.
- You should receive a Goody Bag, and a Toothbrush.
Open your inventory, and use the Toothbrush located in the Consumables section, and you will have finally been granted the ability to brush your Guardian's teeth! If you've finished all the quest steps correctly, you will now have a Used Toothbrush sitting in your inventory.
There is quest chain to receive toothbrush:
The triumph for the FotL 2019 to brush your teeth can be completed by flooding a quest began by visiting Eris on the moon. She will give you an item, which will have a description leading you to a planetary vendor. The first one is The Spider. From there, you will get an easy objective to complete, followed by another item. Follow this chain throughout the solar system and you’ll get a toothbrush.
Quest item should be consumable item:
Look in consumables and look for a common rarity consumable with a festival of the lost icon
Also looks like there are some prerequisites:
In order to participate in this activity, all new light players will have to:
Achieve Power Level 770 or more
Complete Escape The Comsodrome Quest to unlock the tower.
Sources: reddit, Festival Of Lost all loot guide