Dental Caries, Denture, Partial, Removable
Conditions
Keywords
composite bactericidal, caries prevention
Brief summary
Nobio has developed dental restorative materials with long term antibacterial properties in order to fight recurrent decay/caries around restorations. These composites with incorporated non-leaching antibacterial agents might overcome the vicious circle of newly developed cavities around freshly placed fillings. The investigators will ask lower partial denture wearers to allow them to place a gap model with the Nobio-composite and enamel slab in one denture flange. In the other denture flange a gap model with a standard composite will be placed as control. In the laboratory the investigators will test with established methods for demineralization/caries prevention in the test and control enamel slabs, respectively.
Detailed description
As a major issue in dentistry, it has been stated that two-thirds of all restorative dentistry involves the replacement of failed restorations. Secondary caries indicates a lesion developing at the margins of an existing restoration and is the major reason for replacement of amalgam and composite resin restorations in operative dentistry. In research the use of experimental intra-oral caries models dealing with caries prevention has increased. The most realistic experimental model is the in vivo model that uses living teeth, followed by the in situ model using specimens with natural surfaces held in the mouth during the experimental period. In situ models have the potential to study both fundamental aspects of the caries process as well as more applied research problems in caries prevention in human subjects without actually causing caries in the natural dentition. To simulate a failed interface between a tooth and a restoration, a gap can be formed between an enamel slab and the restoration prior to a cariogenic challenge. The gap-model will be inserted for instance into the denture flanges, and the cariogenic challenge occurs inside the mouth during the wear period.. Nobio has developed dental restorative materials with long term antibacterial properties in order to fight recurrent decay around restorations. These composites with incorporated non-leaching antibacterial agents might overcome the vicious circle of newly developed cavities around freshly placed fillings. The ongoing caries activity due to bacteria around the filling may be interrupted by quaternary ammonium silica dioxide (QASi) particles incorporated in the test composite at 1.2% (by weight). These particles are members of the Nobio Antimicrobial Particle (NAP) family (Nobio, Israel). QASi are synthesized to form a high concentration of antimicrobial groups that are covalently-bound onto a carrier core, such as silica. The resulting micro or nano-sized QASi particles are mixed with other fillers of the dental composite material, during manufacturing. Following in situ placement and light-initiated polymerization, QASi particles are permanently retained in the final dental restoration. Laboratory studies have shown that the quaternary ammonium silica particles are potent antibacterial agents, do not leach out in contrast to other antimicrobials or caries preventive active substances, inhibit the breakdown of the composite, and maintain antibacterial activity over time. The study is an in situ study. Subjects, wearing lower partial dentures with acrylic flanges on both sides of the mouth will be recruited. On each side of the denture an enamel slab will be placed next to a composite, separated by a tiny gap. On one side of the denture the composite will be Nobio's antibacterial composite, on the other side a regular composite (a Nobio composite w/o particles or another commercial composite will serve as control material. Enamel slab and composite will be recessed into the flange, allowing microbial plaque to accumulate on top of it and especially in the gap. After wearing the dentures for four weeks with the slabs, decalcification - ΔZ mineral loss - in the enamel slabs adjacent to the gap will be determined by cross-section microhardness testing in the laboratory. Average ΔZ mineral loss will be calculated for the Nobio group and the control group, and difference will be tested for statistical significance.
Interventions
DEVICENobio composite
Nobio has developed a bactericidal composite, which does not leak out the bactericidal nano fillers
DEVICEtraditional composite
traditional composite which has no bactericidal activities
Sponsors
Nobio Ltd.
University of California, San Francisco
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
DOUBLE (Subject, Outcomes Assessor)
Masking description
Subjects are not aware, which side of the denture will harbor the gap model with the Nobio composite and which side harbors the traditional composite. Laboratory microhardness measurements will be conducted while keeping the operator blind.
Intervention model description
In-situ testing using a gap model inside the two flanges of a removable partial denture
Eligibility
Sex/Gender
ALL
Age
18 Years to 80 Years
Healthy volunteers
Yes
Inclusion criteria
* aged between 18 and 80 years, * have at least six natural teeth remaining and have a recent history of dental caries * wearing lower partial denture (with replaced teeth on both sides of the mouth) * willing to wear their denture during the night * are in good health, of either gender * are in good current oral health with no active caries or periodontal disease (but with a history of caries) * have an understanding of the study * have saliva flow within the normal range (stimulated saliva flow rate of greater than 0.7 ml/minute) * no antibiotics for the last three months * willing to comply with all study procedures and protocols, * residing in San Francisco or other nearby locales with community water fluoridation (to eliminate water fluoridation as a potential confounding variable) * able to give written consent themselves * must be able to read and understand English * willing to sign the Authorization for Release of Personal Health Information and Use of Personally Unidentified Study Data for Research form; data will only be used for research
Exclusion criteria
* subjects who have less than 6 natural teeth remaining * subjects who have used a 5,000 ppm fluoride toothpaste in the last 6 months * subjects who have used Chlorhexidine or any other antimicrobials (cetylpyridinium etc.) in the last 6 months * show evidence of extremely poor oral hygiene * subjects suffering from systemic diseases, significant past or medical history with conditions that may affect oral health or oral flora (i.e. diabetes, HIV, heart conditions that require antibiotic prophylaxis) * taking medications that may affect the oral flora or salivary flow (e.g. antibiotic use in the past three months, drugs associated with dry mouth / xerostomia) * other conditions that may decrease the likelihood of adhering to study protocol * in-office fluoride treatment within the last three months * subjects who will leave the area and are unable to complete the study
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Mineral Loss ΔZ | mineral loss ΔZ is determined after the 4 week wearing period | The mineral loss is determined in the laboratory using cross-sectional microhardness testings of the enamel after the 4-weeks wearing period of the gap-model. The overall relative mineral loss, ΔZ, for each sample is calculated by creating a hardness profile curve by plotting normalized volume percent mineral against distance from the outer enamel surface. The area under the curve that represents ΔZ (µm \* vol % mineral) is calculated using Simpson's integration rule. |
Countries
United States
Participant flow
Recruitment details
each participant enrolled had TWO flanges (right and left side of the mouth) in her/his removable partial denture; the study design is a split-mouth design - in one side the Nobio Flange- the Nobio composite was inserted, one the control side - the control flange - the traditional control composite was inserted
Participants by arm
| Arm | Count |
|---|---|
| All Study Participants All participants received both the Nobio flange and the traditional composite control flange.
On the Nobio flange side of the lower partial denture the gap model will include a double sterilized piece of human enamel, a small gap, and next to it the Nobio composite.
Nobio composite: Nobio has developed a bactericidal composite, which does not leak out the bactericidal nano fillers
On the traditional composite control flange side of the lower same partial denture the gap model will include a double sterilized piece of human enamel, a small gap, and next to it a traditional composite.
traditional composite: traditional composite which has no bactericidal activities | 25 |
| Total | 25 |
Baseline characteristics
| Characteristic | All Study Participants |
|---|---|
| Age, Continuous | 63.7 years STANDARD_DEVIATION 14.1 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 3 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 22 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Region of Enrollment United States | 25 participants |
| Sex: Female, Male Female | 8 Participants |
| Sex: Female, Male Male | 17 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 25 | 0 / 25 |
| other Total, other adverse events | 0 / 25 | 0 / 25 |
| serious Total, serious adverse events | 0 / 25 | 0 / 25 |
Outcome results
Primary
Mineral Loss ΔZ
The mineral loss is determined in the laboratory using cross-sectional microhardness testings of the enamel after the 4-weeks wearing period of the gap-model. The overall relative mineral loss, ΔZ, for each sample is calculated by creating a hardness profile curve by plotting normalized volume percent mineral against distance from the outer enamel surface. The area under the curve that represents ΔZ (µm \* vol % mineral) is calculated using Simpson's integration rule.
Time frame: mineral loss ΔZ is determined after the 4 week wearing period
Population: From the original 25 subjects data of the first 5 subjects were used for a sample size calculation. The sample size calculation determined data from 17 subjects would be needed. To account for loss due to follow-up issues, we recruited 20 subjects. 1 subject did not follow the instructions (required wearing time), 2 sample/data sets could not be retrieved due to Covid-19 shelter-in-place restrictions. Results of the first 5 were not included due to statisticians concerns for clean statistics.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Nobio Flange | Mineral Loss ΔZ | 235 vol% * μm] | Standard Deviation 354 |
| Traditional Composite Flange | Mineral Loss ΔZ | 774 vol% * μm] | Standard Deviation 556 |