Oral Irrigation Bears Consideration

Oral irrigation was first introduced to the dental profession in 1962. Since then, over 45 published clinical trials have unequivocally demonstrated the safety and efficacy of daily irrigation. In spite of these consistent clinical outcomes, professional opinion has fluctuated over the past 40 years, often based on anecdotal information or assumptions. One stumbling block to recommending daily irrigation has been the inconsistent reduction in the plaque (biofilm) indices traditionally used in clinical trials. Regardless of the results for the plaque indices, other clinical parameters were consistently reduced, culminating in reduction of disease. Others have based opinions on the efficacy of daily irrigation on the outcomes of in-office, single-delivery irrigation, where the medicament is delivered via a syringe, ultrasonic scaler, or mechanized device, often after a scaling and root planing procedure. Home irrigation and in-office irrigation have two entirely different bodies of evidence and should not be considered collectively.

The purpose of daily irrigation is to nonspecifically reduce the subgingival biofilm and its by-products that lead to the initiation or progression of periodontal infections. Individuals with varying levels of infection and compromising situations, as well as those with good oral hygiene, can benefit from the use of daily water irrigation.

Mechanism of action

Irrigation devices provide either a steady or pulsed stream of water or other solution. Studies have found that pulsation and pressure are critical features of effective irrigation. Pulsating devices allow for a compression and decompression phase, which results in expedient removal of bacteria from the gingival sulcus or periodontal pocket. These devices have been shown to be three times as effective as continuous-stream or syringe-type devices. The most effective pressure setting is medium to high (50 psi to 90 psi).^1,2

Pulsation and pressure lead to subgingival access of the irrigant. This is the result of two zones of hydrokinetic activity:

1. the impact zone, where the solution initially contacts the tooth or gingival margin, and
2. the flushing zone, the subgingival depth of delivery.³

Depth of delivery

The target of daily irrigation is the subgingival biofilm. Subgingival access is dependent on tip design and pocket depth. Traditional jet tips placed at or near the gingival margin can penetrate 44 to 71 percent of the pocket depth.⁴ Specialized tips (Pik Pocket^® subgingival irrigation tip, Waterpik Technologies, Fort Collins, Colo.) placed below the gingival margin can deliver an irrigant to 90 percent of a 6 mm pocket and 64 percent ≥ 7 mm. In comparison, rinsing penetrates to 21 percent of the depth of the pocket.⁵

Impact on clinical parameters and inflammatory response

In the past, the focus on efficacy for self-care products was supragingival plaque removal as measured by a plaque index. Current plaque (biofilm) indices do not measure the quality or composition of the biofilm and are, therefore, limiting. Today, with increased knowledge of the pathogenesis of periodontal disease, efficacy is more appropriately measured by the reduction of bleeding, gingivitis, pathogenic bacteria, and immunoinflammatory responses.

Daily irrigation consistently has shown significant reductions in bleeding on probing and gingivitis regardless of reduction in the plaque index. Flemmig found a 50 percent reduction in bleeding for individuals who irrigated daily with water compared to routine oral hygiene.⁶ Others have found similar results supporting the benefit of daily irrigation for individuals who brush and floss.^7,8

Toothbrushes, flossing, and rinsing are limiting in their ability to access the subgingival flora. Cobb and colleagues found a significant reduction of pathogenic bacteria in 6 mm pockets.³ Others have demonstrated significant reductions in subgingival biofilm for subjects using irrigation compared to control (no irrigation).^9,10

It is well-documented that the pro-inflammatory mediators interleukin-1β (IL-1β) and prostaglandin E₂ (PGE₂) are associated with destructive changes in inflamed periodontal tissue, especially bone resorption. A study by Cutler and colleagues evaluated the outcomes for IL-1β, PGE₂, interleukin 10 (IL-10) and interferon-γ (IFNγ) in GCF. Along with a significant reduction in traditional clinical parameters (PPD, BOP, GI, and PI), the researchers found that home irrigation significantly reduced IL-1β and PGE₂ and noted an increase in IL-10, an anti-inflammatory mediator, compared to routine oral hygiene.⁸

Delivery of antimicrobials

An oral irrigator is the ideal vehicle for at-home delivery of antimicrobials due to enhanced subgingival access compared to rinsing. The majority of studies delivering an antimicrobial have been done with full-strength essential oils and chlorhexidine at varying strengths (0.02 percent, 0.04 percent, and 0.06 percent). In most instances, there is a greater reduction of clinical parameters compared to control or water irrigation. It is important to note that even though there was a significant difference between the agent and water, water still showed significant outcomes from baseline compared to control, making it a convenient, cost-effective agent.^9,10,11

Special considerations

Home irrigation has been studied with individuals who are living with diabetes, who have implants, or who have orthodontic appliances. It is accepted that individuals with diabetes are at a higher risk for periodontal infections. Optimal oral hygiene is imperative. A study by Al-Mubarek and colleagues evaluated the use of twice daily irrigation using the Pik Pocket^® tip and water on individuals with diabetes. The three-month study showed a significant reduction in biofilm, gingivitis, and bleeding on probing. In addition, there was a significant down regulation of the pro-inflammatory mediators IL-1β and PGE₂ compared to routine oral hygiene.¹²

The use of an oral irrigator on individuals with implants has only been tested using the low-pressure Pik Pocket^® tip. The study measured the efficacy of delivering 0.06 percent chlorhexidine on clinical parameters compared to rinsing with 0.12 percent CHX. The irrigation group had a significantly greater reduction in PI, MGI, and calculus index compared to rinsing.¹³ Although some recommend it, a jet tip has not been tested for safety and efficacy with an implant.

In spite of good oral hygiene, many individuals with orthodontic appliances will develop gingivitis. Due to the challenges of maintaining optimal oral health during orthodontic therapy, an oral irrigator has been shown to be an effective tool. Researchers found that oral irrigation coupled with a manual or power toothbrush significantly reduced bleeding and inflammation better than a manual brush alone.¹⁴

Implications for practice

Providing evidenced-based self-care recommendations is often challenging due to the limited body of scientific evidence and the emotional attachment to traditions such as manual brushing and flossing. Moving toward a client-centered practice requires including scientific findings, practical experience, and patient preferences into comprehensive treatment plans and evaluations.

Oral irrigation is an easy, effective, and low-cost procedure for most individuals. Efficacy is well-documented, and it has been tested on multiple patient types such as those with gingivitis, periodontal maintenance, implants, crown and bridge, diabetes, and orthodontic appliances. When evaluating different irrigators (dental water jets), keep in mind that products are not equivalent in design, pulsations, and pressure. The majority of the clinical evidence has been demonstrated on one brand of irrigator. Therefore, expectations of similar clinical outcomes on products of different brands cannot be assumed. Ask the manufacturer for studies specific to its product.

References

1. Bhaskar S, et al. Waterjet devices in dental practice. J Periodontol 1971; 42:658-664.
2. Selting WJ, et al. Water jet direction and periodontal pocket debridement. J Periodontol 1972; 43:569-572.
3. Cobb CM, et al. Ultrastructural examination of human periodontal pockets following the use of an oral irrigation device in vivo. J Periodontol 1988; 59:155-163.
4. Eakle S, et al. Depth of penetration into periodontal pockets with oral irrigation. J Clin Periodontol 1986; 13:39-44.
5. Braun R, Ciancio S. Subgingival delivery by an oral irrigating device. J Periodontol 1992; 63:469-472.
6. Flemmig TF, et al. Adjunctive supragingival irrigation with acetylsalicylic acid in periodontal supportive therapy. J Clin Periodontol 1995; 22:427-433.
7. Newman MG, et al. Effectiveness of adjunctive irrigation in early periodontitis: Multi-center evaluation. J Periodontol 1994; 65:224-229.
8. Cutler C, et al. Clinical benefits of oral irrigation for periodontitis are related to reduction of pro-inflammatory cytokine levels and plaque. J Clin Periodontol 2000; 27:134-143.
9. Chaves ES, et al. Mechanism of irrigation effects on gingivitis. J Periodontol 1994; 65:1016-1021.
10. Jolkovsky DL, et al. Clinical and microbiological effects of subgingival and gingival marginal irrigation with chlorhexidine gluconate. J Periodontol 1990; 61:663-669.
11. Ciancio SG, et al. Effect of a chemotherapeutic agent delivered by an oral irrigation device on plaque, gingivitis, and subgingival microflora. J Periodontol 1989; 60:310-315.
12. Al-Mubarak S, et al. Comparative evaluation of adjunctive oral irrigation in diabetes. J Clin Periodontol 2003; 29:295-300.
13. Felo A, et al. Effects of subgingival chlorhexidine irrigation on peri-implant maintenance. Am J Dent 1997; 10:107-110.
14. Burch JG, et al. A two-month study of the effects of oral irrigation and automatic toothbrush use in an adult orthodontic population with fixed appliances. Am J Orthod Dentofac Orthop 1994; 106:121-126.

Deborah M. Lyle, RDH, MS
Ms. Lyle has 25 years of dental experience, including faculty appointments, clinical practice, and research. She is currently employed by Waterpik Technologies as the manager of professional marketing and education. You may contact her at [email protected].