This clinical trial is being conducted to study peri-implant mucositis (inflammation in the gums around dental implant that does not extend into the implant-supporting bone). There are currently no available treatment options able to provide long-term resolution of implant gum inflammation even with our current gold standard treatment of non-surgical cleanings and oral hygiene instructions. The purpose of the study is to compare the effect of crown glaze removal and subsequent polishing in addition to mechanical debridement compared to only mechanical debridement on the implant affected by implant gum inflammation.

In this study, participants will be randomized (put into a group by chance) into one of 2 study groups, groups A and B.

Group A: The implant crown will be cleaned with titanium scaling instruments and powered instruments. The screw-retained crown will be removed and the remaining build-up on the crown will be photographed. The crown will then be sent to a lab technician who will remove the glaze and polish the crown only in the areas that sit under the gums.

Group B: The implant crown will be cleaned with titanium scaling instruments and powered instruments. The screw-retained crown will be removed and the remaining build-up on the crown will be photographed. The crown will then be sent to a lab technician to perform a superficial cleaning only.

In both groups, the crown will be placed back on the implant and customized oral hygiene instructions will be provided.

The study will require four appointment. Appointment #1 is the screening appointment and will take 30-60 minutes. Appointment #2 is when treatment is delivered and will occur within 4 weeks of appointment #1. Appointment #3 is for the short-term follow-up and will occur within 60-70 days of appointment #2. Appointment #4 is for the long-term follow-up and will occur within 12-13 months of appointment #2. All these appointment will be in an outpatient setting at the institutional graduate periodontics clinic.

A total of 2 x-rays will be taken of the implant. One will be taken during appointment #1 to assess the bone around the implant. One will be taken during appointment #2 to ensure that the crown is fully seated when the crown is re-inserted.

The following information will be collected in appointment #1: gum measurements around the implants, how tight the implant contacts adjacent teeth, when the crown was delivered, previous cleanings around the implant, age, sex, gender, previous systemic antibiotic use in the last 2 weeks, smoking habits, presence of diabetes and HbA1C values.

At appointments #2, 3, and 4, the following information will be collected: plaque around implant, gum measurements around implants, previous systemic antibiotic use in the last 2 weeks, smoking habits, presence of diabetes and HbA1C values, gum fluid samples around the implant crown. In appointment #4, additionally, information on how the implant has been cleaned throughout the year will be collected.

The study's objectives are:

1. To determine whether a smooth crown surface (<0.2 μm Ra) can be established in-vitro after glaze removal and polishing based on adapted protocol from Go et al., 2019.
2. To determine the effectiveness of submucosal non-surgical hand and powered instrumentation in removal of plaque and calculus.
3. To assess the short- and long-term effectiveness of submucosal zirconia glaze removal and polishing as an adjunct to non-surgical therapy for treatment of persistent peri-implant mucositis. The null hypothesis is that the polishing protocol will not produce any significant differences in the resolution of inflammation compared to crown removal as part of the non-surgical debridement.

Inclusion Criteria:

• At least 1 single screw-retained zirconia glazed implant crown which is in function for at least 1 year, with adequate contact points, submucosal crown margins, no adjacent implants, adequate keratinized tissue (2mm or more), and peri-implant mucositis that persists despite recent (within the past 6 months) non-surgical debridement

Exclusion Criteria:

• Contraindications to routine dental treatment Open interproximal contacts, splinted implant prosthesis, peri-implant health, peri-implantitis, cemented crown , removable implant prosthesis, recession past the implant platform Systemic antibiotic use within the last 2 weeks heavy smokers (more than 10 cigarettes/day) uncontrolled diabetes (HbA1C more than 7.0%)