Management of primary root caries using ozone therapies
Submitted (and Awarded) to the University of London
for the Degree of Doctor of Philosophy
Department of Adult Oral Health Barts and the London Queen Mary’s
School of Medicine and Dentistry,
Turner Street, London E1 2AD United Kingdom
The overall aim of this study was to assess the ability of ozone therapies to reverse the clinical severity of primary root carious
lesions (PRCLs). In addition, novel methods to detect PRCLs using the Electrical Caries Monitor (ECM) and the Resilience Caries Monitor (RCM) were used. 200 PRCLs were examined in vitro to relate the ECM and RCM readings to clinical criteria used to detect PRCLs. Significant differences in ECM values were found for colour, hardness and all five classes of severity of PRCLs, in addition to sound root tissues, but not for the RCM values.
In the second part of this study, the use of ozone was considered. Initially, the anti-microbial effects of ozone on PRCLs were tested, and a significant reduction in total colony forming units (tcfus) was observed in the ozone-treated groups. Secondly, a significant reduction in tcfus was observed in ozone-treated samples for Streptococcus mutans and Streptococcus sobrinus. A further in vivo study demonstrated a significant reduction in tcfus. In order to assess the safety of ozone during these treatments, the maximum ozone detectable levels (ppm) adjacent to the point of the application were measured in vivo and in vitro. These investigations revealed that the mean maximal detectable levels of ozone were all within EU and FDA guidelines. A further longitudinal study assessed the safety and efficacy of ozone either with or without a root sealant, for the management of PRCLs. In this longitudinal study, the ECM, DIAGNOdent and clinical detection criteria were used and there were
four experimental groups involved:
Group 1. Ozone application only was performed for a period of 10 s on
Group 2. Neither ozone nor root sealant was applied to the PRCLs.
Group 3. Both ozone treatment and a root sealant were applied to PRCLs.
Group 4. A root sealant only was applied to PRCLs.
At baseline, and after 1 and 3 months, ECM and DIAGNOdent readings were obtained and each PRCL was then clinically
assessed. The longitudinal study revealed that at 1 month recall, 26.5% of PRCLs had reversed from severity index 2 to 0 (i.e., hard) in the ozone group, whilst in the control group, 1.5% of PRCLs got worse (p < 0.001) and 54.4% of lesions reversed from severity index 2 to 1 in the ozone group compared to those in the control group (p <0.001). After 3 months, 13.5% of PRCLs reversed from severity index 1 to 0 (i.e., hard) in the ozone group, whilst none of the lesions reversed in the control group when compared to the baseline results (p < 0.001). Furthermore, 23.1% of lesions reversed from severity index 2 to 1 in the group receiving ozone alone compared to only 5.9% in the control group (p < 0.001). The ECM and DIAGNOdent readings showed improvements in the ozone only group when compared to the control group after 1 and 3 months (p < 0.001). The ozone and sealant group also had greater improvements in the ECM and DIAGNOdent values when compared to the sealant only group
after 1 and 3 months (p < 0.05). In addition, Modified USPHS criteria after 3 months showed that there were 53% of intact sealants in the ozone and sealant group, whilst 40% of intact sealants were present in the sealant only group.
The use of the ECM has promise for accurately detecting PRCLs in clinical practice. Leathery lesions can be treated non-operatively either by using ozone. The root sealant showed a reduced retention at 3 months but was retained better on ozone treated PRCLs.