1 Introduction

Oral health has recently emerged as a health care priority. This has been due in large part to the well-established connection between oral and systemic health, as well as the increased recognition of the many barriers to routine dental care experienced disproportionately by patients that are older, economically disadvantaged, members of racial or ethnic minority groups, or disabled or home bound.¹ The implications are most pronounced among those older than 65 years of age. In this population, approximately 19% of patients are edentulous, more than half have moderate or severe periodontal disease, and approximately 50% do not go to the dentist, with cost being the most cited factor.^1,2 These statistics should be of heightened concern to arthroplasty surgeons, as the average ages of Americans undergoing primary total hip (THA) and knee (TKA) arthroplasty in 2019 were 67.4 and 66.7 years of age, respectively.³

At the same time, significant advances in the perioperative optimization of patients undergoing THA and TKA has been critical in maximizing patient outcomes and minimizing peri- and postoperative complications, the most consequential and costly of which is the periprosthetic joint infection (PJI). The prevalence of numerous patient comorbidities and their effects on outcomes in THA and TKA, including hypertension, diabetes mellitus, obesity, dyslipidemia, chronic kidney disease, tobacco use, and congestive heart failure, have been extensively studied.^4–6 However, comparatively less literature exists which critically evaluates the effects of perioperative oral health on outcomes following THA or TKA.

This review aims to introduce the importance of oral health as a small but crucial portion of a patient's overall perioperative management. It also serves to provide a critical analysis of the ways in which a patient's oral health status can impact the process of THA and TKA from preoperative medical optimization through surgery and recovery. Finally, we'll attempt to provide relevant, evidence-based guidelines for physicians to help guide their patients through dental interventions safely in the months and years following a THA or TKA.

2 Background

The term oral health encompasses far more than care for the teeth. It includes care for the gums, supporting tissue, hard and soft palates, mucosal lining, tongue, lips, salivary glands, muscles of mastication, and the jaw.⁷ Over the course of the twentieth century, significant advances in biomedical research have led to improvements in American oral health care; namely through the discovery of the properties of fluoride and its now ubiquitous presence in much of the American supply of drinking water.⁷ However, the positive effects have been disproportionate; with economically disadvantaged and elderly Americans reaping fewer of these benefits.⁷

In 2000, the United States Surgeon General issued a report emphasizing the importance of oral healthcare in America and its inextricable link to one's overall health status. For example, an exam of the oral cavity can provide early access to physical signs and symptoms of local and generalized disease and risk factor exposure, including nutritional deficiencies, systemic diseases, microbial infections, immune disorders, and traumatic injuries.⁷ With regards to diabetes in particular, research has demonstrated that chronic periodontal disease may worsen glucose control and that treatment of this disease has demonstrated a 10–20% improvement in glycemic control.^8,9 This may be of benefit as recent research has demonstrated a higher risk of PJI in patients with poor postoperative glycemic control.¹⁰

The possibility of the oral cavity precipitating systemic infection is of particular concern to the arthroplasty surgeon. Musculoskeletal infections, including PJIs, continue to be a leading cause of chronic pain and functional limitation, and their prevalence continues to increase with increasing rates of obesity and diabetes found within the American populace.¹¹ Furthermore, PJIs continue to burden the American healthcare system, with estimates for total cost of PJI treatment in the United States projected to be $1.69 billion by 2020.¹¹

The prevailing hypothesis is that transient bacteremia provoked by preexisting dental infections or dental procedures leads to hematogenous seeding of the prosthetic joint and subsequent late PJI. Such a mechanism of infection was initially demonstrated by Blomgren and Lindgren in rabbit models in 1980.¹² Since then, more authors have subsequently implicated this mechanism in the development of PJI.^13–15 The consequences of this mechanism are heightened in the largely geriatric population of patients undergoing routine primary THA and TKA, where reports have shown that these patients are more likely to have xerostomia, ulceration of the intraoral mucosa, fungal infections such as candidiasis, and gingival recession predisposing patients to root caries.^7,16 These risks are further compounded when the particular health maintenance habits of this population are taken into account, as the exclusion of dental care coverage from Medicare leaves lower income beneficiaries, 74% of whom receive no routine dental care, at higher risk of tooth decay, periodontal disease, edentulism, and the negative infectious sequelae of these conditions.¹⁷

This transient bacteremia originating from the mouth occurs daily. It can happen in healthy hosts with common practices of dental hygiene, such as tooth-brushing or flossing, however, it is more common in those with poor dentition and dental decay. Some estimates place the frequency of oral bacteremia as high as 44% after toothbrushing,¹⁸ 41% after flossing,¹⁹ and 17% after chewing.^20,21 Invasive dental procedures, most notably dental extractions, periodontal procedures, and cleaning when bleeding is anticipated, are another source of oral bacteremia.²² To this end, antibiotics have historically been administered prior to invasive dental procedures in an effort to decrease the prevalence of bacteremia stemming from the oral cavity.²³ Multiple prophylactic antibiotics, including amoxicillin, clindamycin, and penicillin, have been shown to decrease the rate of bacteremia following dental procedures²⁴ (Table 1). However, the magnitude and duration of bacteremia caused by these procedures is quite low, and whether or not such a burden causes clinically relevant infectious disease, including PJIs, is currently unknown.²⁴

3 Oral health considerations prior to total hip or knee arthroplasty

The minimization of postoperative infections is a shared aim of all surgical disciplines. To this end, patients are routinely required to undergo close scrutiny prior to elective surgery. This often includes preoperative correction of modifiable risk factors, recognition of postoperative risk factors that may lead to complications, and ensuring that there are no active infections at remote sites that may result in bacteremia prior to proceeding with the operation.^25–27 This necessitates a multidisciplinary approach to patient optimization (Table 2).

The oral cavity has been implicated as a source of postoperative pneumonia and surgical site infection in patients undergoing elective spine, colorectal, esophageal, and thoracic surgery.^28–30 Prior research has focused largely on the connection between oral care and the development of postoperative pneumonia secondary to the aspiration of various oral pathogens. However, the risks of aspiration pneumonia are minimized in the typical THA or TKA recipient, owing to the elective nature of the procedure as well as the widespread adoption of neuraxial anesthesia and rapid mobilization protocols. For this reason, improvement in perioperative oral health care protocols should be examined for their role in alleviating the major sources of morbidity and cost in total hip and knee arthroplasty surgery, namely post-operative surgical site infections (SSI) and PJI.

There currently exists no standardized protocol or official recommendations regarding the utility of dental assessment and treatment prior to elective THA or TKA. Some orthopedic practices have instituted preoperative dental evaluations prior to surgery, however, any effects of this practice on the rate of PJIs are not well established.^31,32 Furthermore, many dentists have advocated strongly for perioperative dental evaluations generally, emphasizing their utility in the optimization of patient outcomes and the ability for cost-containment associated with the minimization of preventable perioperative complications. Yasny and Herlich attributed this lack of focus on preoperative oral health to historical omission of the importance oral health in the minds of many surgeons, deficient patient education as to the benefits of routine dental care, and the numerous barriers in place to routine oral health care, both financial and in terms of accessibility.³³ This is especially disconcerting, as many patients with potentially hazardous intraoral infections could be diagnosed and treated with a relatively cursory and easy-to-perform dental exam.³⁴ To improve access, national initiatives have been in place over the past twenty years to encourage oral health training for family physicians and other nondental providers, and formal education in oral health is now mandated in all Accreditation Council for Graduate Medical Education (ACGME)- accredited family medicine residency programs.^35,36

While orthopedic specific literature regarding the utility of perioperative oral health promotion is limited, there is data from other surgical disciplines which highlights the positive role these assessments may play in reducing postoperative SSIs. Nobuhara et al. performed a retrospective cohort study of 698 patients undergoing major colorectal cancer surgery, 563 of which received perioperative oral care by dentists or dental hygienists one or more times prior to surgery and 135 that did not. The investigators noted that operation time, blood loss, and perioperative oral management were significantly correlated with the development of SSI, and that not receiving perioperative oral care was indeed a significant risk factor for the development of SSI.³⁷ Similarly, in a case-control study of 78 patients, Mirzashahi et al. demonstrated a statistically significant correlation between preoperative teeth carries and periodontal disease and postoperative surgical site infection (SSI) following elective spine surgery, suggesting that more vigilant perioperative oral healthcare may have a beneficial effect in reducing postoperative infections.³⁸ However, like many studies on the topic it is limited by small sample size, and its case-control study design introduces selection bias as a source of systematic error.

Much of the data regarding the effects of oral bacteremia on the development of PJIs in the orthopedic literature is limited to case reports and small series. There are, however, some case-control studies which attempt to further investigate this relationship, although no causal link has been established. Berbari and colleagues³⁹ performed a prospective, single-center, case-control study comparing 339 hospital inpatients hospitalized with a total hip or knee infection versus 339 non-infected patients who underwent a THA or TKA and were hospitalized during the same period of time. The authors concluded that there was no increased risk of PJI for patients undergoing a high-risk (defined as including dental hygiene, mouth surgery, periodontal treatment, dental extraction, and dental abscess management) or low-risk (defined as including restorative dentistry, dental filling, endodontic treatment, and fluoride treatment) dental procedure who did not take antibiotic prophylaxis compared to those patients that did not undergo a dental procedure (Table 3). Additionally, they concluded that antibiotic prophylaxis in both high and low risk dental procedures did not decrease the rate of PJI. Skaar and colleagues⁴⁰ examined the Medicare Current Beneficiary Survey (MCBS) to perform a case-control study to assess whether dental procedures were associated with the development of PJIs. The authors compared 42 case participants who had PJIs with 126 control participants who underwent THA or TKA without the subsequent development of a PJI. The authors found no statistically significant association between prior invasive dental procedures and subsequent risk for PJIs, calling into question the overall clinical utility of antibiotic prophylaxis prior to invasive dental procedures.

In 2019, Barrere and colleagues²⁷ published a systematic review in an effort to better evaluate the performance of a preoperative dental assessment before orthopedic surgery, focusing mainly on whether there is an association between preoperative dental evaluation and the development of infection, as well as whether the probability of infection is increased in the presence of dental risk factors. The authors concluded that, with regards to case-control studies analyzed, PJI was associated with dental abscess in 2.9% of cases. The authors suggested that the presence of infection was less frequent if a preoperative dental assessment was performed, although definitive conclusions were unable to be made as few of the included studies directly obtained specifics regarding the nature of dental assessments and treatments prior to surgery. The report was further limited by significant heterogeneity in included studies, as few studies currently exist which directly address these aforementioned questions, rendering the authors unable to provide substantial evidence for or against preoperative dental evaluations.

4 Oral health considerations following total hip or knee arthroplasty

PJIs are associated with significant morbidity and mortality.^41,42 The majority of PJIs occur during the perioperative period via direct bacterial inoculation of the surgical wound. Late PJIs, occurring 1–2 years following surgery, are often associated with bacterial seeding through hematogenous transmission from the oropharynx, gastrointestinal, or genitourinary tract.^43,44 Antibiotic prophylaxis prior to invasive dental procedures has been suggested, however, there is a lack of evidence supporting its widespread use.³⁹ Several investigators have demonstrated that the benefits of antibiotic prophylaxis are outweighed by the adverse reactions, including gastrointestinal disturbances, anaphylaxis, and an increased prevalence of multidrug-resistant bacterial infections.^39,45,46

The use of prophylactic antibiotics prior to invasive dental procedures has been debated for more than four decades.^39,47–49 Orthopedic surgeons and dentists have utilized antibiotic prophylaxis to treat the acute asymptomatic bacteremia which frequently occurs following invasive dental procedures with the hopes of preventing the hematogenous development of PJIs. In response, the American Dental Association (ADA) and American Academy of Orthopaedic Surgeons (AAOS) published a joint statement in 2012 recommending against the routine use of prophylactic antibiotics in most patients prior to invasive dental work.⁵⁰ Further supporting the AAOS and ADA recommendations, Mougeot and colleagues reported that acute asymptomatic bacteremia is exceedingly common, occurring among 80% and 59% of patients undergoing single tooth extraction with placebo and amoxicillin, respectively.⁵¹ Moreover, 32% of patients who brushed their teeth were bacteremic, undermining the role of prophylactic antibiotic use prior to invasive dental procedures.⁵¹ Subsequent reports, including the 2018 International Consensus Meeting (ICM) on Musculoskeletal Infection have demonstrated that the body of literature is primarily composed of low-quality studies with no direct evidence indicating that dental procedures predispose patients to PJIs.^44,45 Additionally, there is currently no evidence to suggest the use of prophylactic antibiotics prior to dental procedures reduces the incidence of PJIs. In lieu of prophylactic antibiotics, good oral hygiene and the prompt treatment of oral infections (e.g. periodontal abscesses) is recommended.⁵⁰

Although current AAOS, ADA, and ICM on Musculoskeletal Infection guidelines do not currently recommend prophylactic antibiotic use, the literature these recommendations are based upon is limited.^44,50 It is critical that total joint arthroplasty (TJA) recipients identified as high-risk for PJI (e.g. autoimmune disorders, mechanical valves, or oncologic disease) discuss invasive oropharynx procedures with their orthopaedic surgeon and dentist prior to proceeding.^52,53 Although there are no studies evaluating the role of prophylactic antibiotic use within this high-risk population the risks and benefits of prophylaxis should be critically evaluated prior to initiation.^52,54

5 Future directions

Given the high morbidity and costs associated with PJIs, the effects of oral health on the development of these SSIs and PJIs should be a topic of interest to the orthopedic surgeon. Currently, there exists very little high-quality evidence with which to propose overarching treatment recommendations. Further research, including prospective and randomized control trials, are necessary before a definitive link between dental health and the development of PJI can be established. Further targeted research would also be of benefit to highlight which, if any, specific patient populations would benefit from prophylactic antibiotics prior to invasive dental procedures.

6 Recommendations

Despite the dearth of high-level evidence, multiple common-sense recommendations can be enacted prior to elective arthroplasty surgery. Orthopedic surgeons should play an active role in promoting the maintenance of overall health and well-being of their patients, including the promotion of oral health care. Eliciting an oral health history prior to THA or TKA can provide insight as to one possible risk factor for PJI, while also providing the surgeon with insight into the patient's general overall health. This information can then be used to perioperatively risk stratify and optimize the patient prior to surgery and can help to ensure that all sites of active infection are eliminated preoperatively. Additionally, shared decision making should be implemented in order to make the best decision regarding the use of prophylactic antibiotics prior to both invasive and non-invasive dental procedures on a case-by-case basis. Finally, THA and TKA candidates with poor dentition, active oral pain, or those who have not seen a dentist in the previous two years should see a dentist for oral health assessment prior to elective joint arthroplasty in an effort to ensure the elimination of all oral infectious sources prior to elective joint arthroplasty.

7 Conclusion

As the number of THA and TKA procedures in the U.S. continues to increase dramatically, so too will the number of PJIs. Much work has been done in in identifying and addressing multiple risk factors which may lead to an increased incidence of these morbid and expensive complications. However, little direct evidence exists which links the presence of oral infection to PJI incidence. Given that approximately 50% of patients over the age of 65 seek routine dental care, further research in this area may provide information as to yet another risk factor for PJI which can be identified and treated prior to elective arthroplasty surgery in an effort to optimize surgical outcomes and patient satisfaction.

Funding

No external funding was received for any aspect of this work.

Author's contributions

JRY, ALB, AAA, ADP, CTA, and MRD all contributed equally to the conception, construction, and critical review of this report. JRY is both the lead author and the corresponding author for the manuscript. All authors have read and approved the submission of this manuscript.