Orthodontics and Diabetes UK

How hyperglycaemia affects periodontal health

People with diabetes — both Type 1 and Type 2 — have a significantly elevated risk of periodontal (gum) disease compared with the general population. Research consistently shows a two to three times higher prevalence and severity of periodontitis in diabetic patients, with the risk increasing when blood glucose control is poor. The mechanism involves impaired immune response to oral bacteria, reduced neutrophil function (the white blood cells that fight infection in the gum sulcus), and the formation of advanced glycation end-products that make gum tissue more susceptible to breakdown. When glucose is chronically elevated, the gingival fluid around the teeth changes in composition, creating a more favourable environment for the bacteria that drive bone loss. For orthodontic patients this matters because orthodontic tooth movement through bone depends on a healthy periodontium. Starting braces on a patient with active periodontitis — regardless of diabetes status — accelerates bone loss and should not be done until the gum disease is treated and stable.

Wound healing and bone remodelling in diabetic patients

Orthodontic tooth movement depends on a cycle of bone resorption on the pressure side of a tooth and bone deposition on the tension side. This process is an inflammatory and healing response, and it is slower and less efficient when wound healing is systemically impaired. In patients with poorly controlled diabetes, impaired wound healing has been well documented — post-extraction healing is slower, soft tissue repair is less reliable, and bone quality may be reduced. For orthodontics specifically, some studies suggest that tooth movement speed is reduced in patients with elevated HbA1c, meaning treatment may take longer than estimated. The clinical implication is that treatment planning should account for this variability and that treatment duration estimates made for patients without diabetes may underestimate duration for those with poor control.

HbA1c thresholds for safe orthodontic treatment

HbA1c is the standard measure of long-term blood glucose control in the UK, expressed as a percentage (older units) or mmol/mol (IFCC units). Most orthodontic and dental literature recommends that elective orthodontic treatment should not begin until HbA1c is at or below 7.5% (58 mmol/mol). This threshold reflects a level of control at which the elevated risks — for wound healing, immune response, and bone remodelling — are meaningfully reduced. An HbA1c of 7.5–8% (58–64 mmol/mol) is considered borderline, and starting orthodontic treatment in this range requires a clear conversation with both the orthodontist and the patient's GP or diabetologist. Above 8% (64 mmol/mol), elective orthodontic treatment should generally be deferred until control is improved. These are guidance thresholds, not absolute cut-offs, and the clinical decision should account for the patient's overall medical history and trajectory.

What diabetic patients must disclose at consultation

Before starting any orthodontic treatment, patients with diabetes should disclose their diagnosis, the type of diabetes, their current HbA1c result (a recent result is preferable — within the last three months is ideal), any complications of diabetes affecting circulation or nerve function, current medications including insulin, metformin, SGLT2 inhibitors, or GLP-1 agonists, any history of severe hypoglycaemic episodes, and whether they are under active management from a GP, diabetologist, or diabetes specialist nurse. If your diabetes is not yet well controlled, an honest discussion about timing is more appropriate than proceeding and encountering complications mid-treatment. Orthodontists are not expected to manage your diabetes, but they need this information to make safe clinical decisions about starting treatment, scheduling appointments, and responding if a problem arises during the course of treatment.

More frequent hygiene appointments during treatment

In the general population, orthodontic patients are recommended to attend a dental hygienist or therapist every three to six months during treatment. For patients with diabetes — particularly those with a history of gum disease or moderate glycaemic control — a three-monthly interval is more appropriate, and some cases warrant monthly hygiene visits, especially in the first six months of treatment. This more frequent schedule allows for early detection of any gingival inflammation, professional removal of plaque and calculus that accumulates more readily around brackets and wires, and reinforcement of oral hygiene technique. Fixed braces make plaque control more difficult, and the increased bacterial load around brackets can trigger or worsen periodontal inflammation in susceptible patients. Diabetic patients should also have a formal periodontal assessment before orthodontic treatment starts, including periodontal probing depths and BPE score.

Dry mouth, xerostomia, and decay risk with aligners

Several medications commonly used to manage Type 2 diabetes can cause or worsen dry mouth (xerostomia). Metformin occasionally causes this, and some antihypertensive drugs taken by patients who have developed cardiovascular complications of diabetes are also implicated. Dry mouth is particularly significant for clear aligner patients. Saliva has a protective buffering role against acid and provides enzymes that slow bacterial growth. When saliva flow is reduced, the acid environment inside a tightly fitting aligner — which sits against enamel for 20 to 22 hours a day — is not neutralised as efficiently. This dramatically increases decay risk, particularly around the margins of the aligner. Patients with dry mouth and aligners should drink water frequently throughout the day, avoid any sugary or acidic drinks while the aligners are in, and consider fluoride mouth rinse before fitting the aligner for the night. Discuss medication-related dry mouth with your GP and orthodontist at the outset.

Timing appointments around meals and insulin schedules

Practical management of orthodontic appointments for patients with diabetes requires some thought about timing. Longer appointments — such as debond, placement of a new fixed appliance, or placement of fixed retainers — involve periods of open-mouth work that can affect eating schedules. Patients using insulin should ideally not book treatment to coincide with the period of peak insulin activity after a meal. An early afternoon appointment, roughly 2 hours after lunch, tends to work well for most patients on standard insulin regimens. Patients should eat before attending appointments and should bring a fast-acting glucose source (glucose tablets or a sugary drink) to the waiting room in case of hypoglycaemia. If a patient feels unwell during an appointment, treatment should stop and the patient should be allowed to manage their blood glucose. Orthodontists and their teams should be aware of how to respond to a hypoglycaemic episode in the clinical setting.

Aligner vs fixed braces for diabetic patients

Both aligner therapy and fixed braces are viable options for patients with well-controlled diabetes, but each has trade-offs that are worth discussing explicitly. Clear aligners are removed for eating and brushing, which significantly simplifies oral hygiene — a major advantage for patients at elevated risk of gum disease and decay. However, as described above, dry mouth increases decay risk when aligners are worn for prolonged periods. Fixed braces require meticulous cleaning around brackets and wires, which is harder for patients who already have coordination challenges or for whom hand hygiene is complicated by peripheral neuropathy. Fixed braces also cannot be removed to manage a blood glucose episode, though this is rarely a clinical problem. In general, patients with good manual dexterity, good compliance, and moderate-to-good glycaemic control are often well suited to aligners. Patients who are unlikely to wear aligners consistently enough — for example, those who eat or drink frequently across the day — may be better suited to fixed appliances where compliance is not a variable.

Long-term monitoring after treatment

Orthodontic retention in diabetic patients deserves more attention than in the general population. Fixed retainers, which are bonded wire retainers glued behind the front teeth, are difficult to clean thoroughly and create a plaque trap. In patients with elevated periodontal risk this can be a source of ongoing gingival inflammation. Removable retainers worn at night may carry lower periodontal risk but require vigilant compliance. After orthodontic treatment ends, patients with diabetes should continue attending a hygienist regularly — at least every three to four months — and should have annual periodontal checks that include probing depths. Any looseness of teeth after treatment ends should be reported promptly, as this may indicate bone loss rather than simply relapse of tooth position. The relationship between blood glucose control and oral health continues throughout life, and maintaining good periodontal health is itself beneficial for systemic glycaemic control — the relationship works in both directions.

Useful related pages

This guide is for general information only. It is not a diagnosis, treatment plan, or substitute for advice from a registered dentist or orthodontist.