By Dr. Frits Hoogendijk | Maxillofacial Surgeon | Menlopark Medical Centre, Pretoria
Contact: 082 390 7425
If you are scheduled for a hip or knee replacement, your preparation likely includes blood tests, cardiac clearance, anaesthetic assessment, and imaging of the joint itself. But there is one evaluation that is frequently overlooked — and it involves your teeth.
At our practice, every patient referred for total joint arthroplasty receives a dental cone beam CT scan (CBCT) before surgery. This is not routine practice at most centres. Here is why we believe it should be.
A total hip or knee replacement is one of the most successful operations in modern surgery. For the vast majority of patients, it restores mobility, eliminates pain, and transforms quality of life. But a small percentage of patients — approximately 1 to 2 in every 100 — develop a serious complication called periprosthetic joint infection, or PJI.
PJI occurs when bacteria infect the area around the artificial joint. It can happen shortly after surgery, or months to years later. When it does, the consequences are severe: multiple revision surgeries, prolonged antibiotic treatment, extended hospital admission, and in some cases permanent joint removal. The mortality rate within five years of a PJI diagnosis is around 25% — comparable to many common cancers. It is, in every sense, a catastrophic complication.
Most joint infections are caused by skin bacteria — Staphylococcus aureus and related organisms — introduced at the time of surgery. But a significant proportion of infections that develop months or years after the operation — known as late haematogenous PJI — are caused by bacteria that travel through the bloodstream from a distant source. The mouth is one of the most common of those sources.
Studies have identified oral bacteria as the cause of approximately 10–15% of late haematogenous PJI cases. Patients with natural teeth have been shown to develop late joint infections at nearly three times the rate of edentulous (toothless) patients. The organisms identified — Streptococcus viridans, Streptococcus mutans, Streptococcus sanguis — are characteristic of dental and periapical infections.
The route is straightforward: bacteria from a dental source enter the bloodstream, circulate, and settle on the surface of the prosthetic joint, where they establish a biofilm infection that the immune system cannot clear without surgical intervention.
Here is the critical problem. The dental infections most likely to cause this cascade are ones you cannot feel.
A periapical granuloma or periapical cyst is a chronic infection at the tip of a tooth root. It develops slowly, often over years, as bacteria inside the root canal leak through the apex and provoke an immune response in the surrounding bone. In most patients, the immune system successfully contains the infection — creating a stable, if fragile, equilibrium. The patient feels nothing. There is no pain, no swelling, no obvious sign that anything is wrong.
These lesions are extremely common. Studies of patients presenting for hip and knee replacement have found periapical lesions in approximately 23–35% of patients — roughly one in four. Most of these patients had no idea the lesion existed.
If your dentist has taken dental X-rays and told you everything looks fine, that assessment may not be as reassuring as it sounds — through no fault of your dentist.
Standard dental X-rays, including panoramic jaw X-rays (OPG), are two-dimensional images. They superimpose layers of bone and tissue onto a flat image. A periapical lesion only becomes visible on a conventional X-ray when it has eroded through the dense outer cortex of the jawbone — which requires approximately 30–50% of the surrounding bone to have already been destroyed.
Early-stage lesions, confined to the spongy bone around the root tip, are structurally invisible on 2D imaging. Studies comparing conventional X-ray to CBCT have consistently shown that standard imaging misses approximately one in three periapical lesions that CBCT detects. In some series the detection gap is even larger, with CBCT revealing 2.5 times more periapical pathology in the same patients on conventional X-ray.
The sensitivity figures are telling:
A dental clearance based on an OPG alone may provide false reassurance in a substantial proportion of patients.
Some patients and clinicians ask: even if a silent lesion exists, why would it cause a problem specifically after joint replacement?
The answer lies in what happens to the body after major surgery. The acute physiological stress of an operation — elevated stress hormones, immune modulation, surgical catabolism — temporarily weakens the immune defences that have been keeping a periapical lesion in check. In some patients, this tips the balance: a previously quiescent granuloma undergoes acute flare-up. The contained infection breaks through its barrier, producing swelling, pain, and spreading infection — what is known as a phoenix abscess.
This dental emergency cannot be deferred. An acute abscess requires immediate treatment: emergency extraction, drainage, or surgical intervention. Unlike a routine extraction or dental cleaning, this emergency procedure disrupts an established active infection, releasing bacteria directly into the circulation in large numbers. It is this high-magnitude bacteraemia — occurring in the first three months after joint replacement, when the prosthetic surface is still integrating with bone and is most susceptible to haematogenous seeding — that creates the conditions for PJI.
Every link in this chain is preventable — if the lesion is identified and treated before surgery.
CBCT is a three-dimensional imaging technology that provides detailed, multi-planar views of the teeth, jawbone, and surrounding structures with no anatomical superimposition. It has become the gold standard for detecting periapical pathology.
The scan takes approximately one to two minutes. The radiation dose — 34 to 131 microsieverts for a medium to large field of view — is equivalent to a few days of natural background radiation and a fraction of the dose from a conventional medical CT scan. It is safe, fast, and non-invasive.
When interpreted by a maxillofacial surgeon with specific training in jaw pathology, a CBCT scan can detect not only periapical lesions, but also periodontal bone loss, cystic lesions, root fractures, and other pathology that would be missed on conventional imaging — some of which may have independent significance for surgical planning and post-operative recovery.
If a periapical lesion is identified, treatment is straightforward in most cases. Options include root canal therapy to eliminate the intraradicular infection while preserving the tooth, or extraction. Both are definitive: they eliminate the bacterial reservoir and remove the substrate for the post-operative cascade described above.
Current guidelines recommend that all active dental infections be resolved with a minimum three-week healing period before joint replacement surgery proceeds. Elective oral surgical procedures (extractions, implants) should be completed at least one to three weeks pre-operatively. These timeframes are manageable within standard pre-operative planning.
The intervention cost is low. The radiation dose is negligible. The treatment is well-tolerated. And the potential benefit — preventing one of the most devastating complications in orthopaedic surgery — is substantial.
It is important to be transparent: universal CBCT-based pre-operative dental screening is not currently mandated by international guidelines, including the 2024 AAOS/AAHKS Clinical Practice Guideline on Dental Management Before and After Total Joint Arthroplasty. This guideline does not recommend routine dental clearance for all patients, and grades the evidence as limited strength.
However, this grading reflects an absence of prospective randomised trial data — not an absence of biological plausibility or clinical rationale. No study has specifically examined whether CBCT-based detection and treatment of periapical lesions reduces PJI rates. The data needed to definitively answer this question does not yet exist because the protocol has not been systematically studied. Guidelines can only recommend what has been tested.
What has been established is this: periapical lesions are common, asymptomatic, underdetected by conventional imaging, capable of generating high-magnitude bacteraemia through acute exacerbation, and present a foreseeable cascade of events in the post-operative period. CBCT is the most sensitive available tool for detecting them. The radiation burden is negligible. The cost of missed pathology is potentially catastrophic.
In this context, the precautionary principle is appropriate. We choose not to wait for definitive RCT data when the intervention is safe, the pathology is prevalent, and the consequence of inaction is irreversible.
If you are planning a total hip or knee replacement — or if you are an orthopaedic surgeon, general practitioner, or physician referring patients for arthroplasty — we invite you to consider pre-operative oral screening as a standard component of the surgical preparation pathway.
A single CBCT scan, interpreted by a trained maxillofacial surgeon, takes minutes and can identify pathology that a lifetime of routine dental X-rays may have missed. If pathology is found and treated before surgery, an entire category of post-operative risk is eliminated.
Before the joint, check the jaw.
For referrals or further information, contact our rooms at:
Dr. Frits Hoogendijk | Maxillofacial Surgeon
Menlopark Medical Centre, Pretoria
082 390 7425
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This article is intended for general information purposes. Clinical decisions should always be made in consultation with qualified healthcare professionals based on individual patient assessment.