Introduction
Resin-based fissure sealants (FS) have been used as a physical barrier in
pit-and-fissures with the aim to reduce biofilm accumulation and prevent the development
of new caries lesions in first permanent molars. Several international guidelines
recommend the use of FS for caries prevention in the paediatric population.
The majority of the FS manufactures recommend the etching of the enamel surface prior to
FS application in order to remove any remaining plaque debris and to increase the surface
contact area by superficial demineralisation of tooth surface. Resin based-fissure
sealants contain light-activated urethane dimethacrylate (UDMA) or bisphenol A-glycidyl
methacrylate (Bis-GMA) resin in its composition which bonds to the etched enamel. Several
clinical studies have investigated the use of an intermediate layer of adhesive system
(primer and bond) in order to increase the bonding strength and increase retention of FS
over time in caries free molars, however little is known on the effect on caries
progression and the choice of FS protocol for treatment of enamel caries lesions.
Another factor that can influence the performance of resin-based fissure sealant due to
hydrophobic characteristics of the material is the presence of saliva contamination (poor
moisture control) during application. Therefore, the stage of eruption, patient's
behaviour and operator experience can play a major role when it comes to FS retention on
tooth surfaces. The majority of clinical trials in the field had trained and experienced
operators, including specialists in paediatric dentistry, which could impact the
translational and external validity of their findings. More studies are needed with less
experienced operators in order to evaluate the effectiveness of FS placement in different
environments.
Therefore, the aim of the present randomised clinical trial is to evaluate the
effectiveness of resin-based fissure sealant placed by undergraduate dental students with
or without an intermediate layer of adhesive system in terms of dentine caries prevention
and retention over time.
Methods
Study Design The present study is a two-parallel arm, controlled, single-blind clinical
trial. This study will be registered at Clinical Trials website and submitted to approval
by the local Ethics Committee (SJH/AMNCH Joint Research Ethics Committee).
Sample Size Calculation For the sample size calculation, we have considered the results
of a previous study from McCafferty & O'Connell 2016 (difference of sealant retention
between the groups of 13%; bonded 92% and non-bonded 79%). The sample size calculation
was performed using https://www.sealedenvelope.com/ website using a significance level of
5% (alpha) and a power of 80% (1-beta). A minimum sample of 112 teeth per group was
required. We increased the sample size by 40% to compensate the cluster effect (more than
one tooth can be included per child) and possible loss to follow-up. The final sample
required is 313 teeth.
Randomisation process The randomisation unit is the tooth and more than one tooth can be
included per child. The website https://www.sealedenvelope.com/simple-randomiser/v1/lists
will be used for randomisation list generation, using blocks of different sizes (4, 6 and
8). Sealed, sequentially numbered, opaque envelopes will be used and opened at the time
of sealant placement.
Operators All sealants will be placed by undergraduate dental students during the
undergraduate clinic in Paediatric Dentistry. The treatment will be supervised by an
experienced dentist/clinical supervisor.
Interventions
Control group (FS)
Cotton roll isolation: cotton roll will be placed buccally and lingually/palatally
to the first permanent molar to be treated. A saliva ejector will be used to remove
any excess of saliva. If the cotton roll are saturared in saliva at any point of the
treatment, they will need to be changed.
Etching of the enamel surface: 17% phosphoric acid will be applied for 15 seconds
over the surface to be sealed (Phosphoric etchant gel - Vococid, VOCO) using the
etch syringe applicator tip.
Washing/drying: a 3-1 syringe will be used to rinse all etch material from the
toothsurface. A high volume suction will be used. Cotton pellets will be changed to
a dry ones at this stage and the surface will be dried for 5s using the air syringe.
Sealant application: a light-curing nano-hybrid fissure sealant material (Grandio
Seal; VOCO) will be applied using the applicator tip. A probe will be used to ensure
that the material is present in all fissures without any air bubbles.
Lightcuring: The material will be lightcured for 20 seconds. The material colour
will change to an opaque off white colour when exposed to light.
Check occlusion: After checking for premature contact points, if there is a need to
remove a excess of material, a superfine diamond bur or a silicone finishing point
can be used for adjustments.
Test group (Adhesive + FS)
Cotton roll isolation: cotton roll will be placed buccally and lingually/palatally
to the first permanent molar to be treated. A saliva ejector will be used to remove
any excess of saliva. If the cotton roll are saturared in saliva at any point of the
treatment, they will need to be changed.
Etching of the enamel surface: 17% phosphoric acid will be applied for 15 seconds
over the surface to be sealed (Phosphoric etchant gel - Vococid, VOCO) using the
etch syringe applicator tip.
Washing/drying: a 3-1 syringe will be used to rinse all etch material from the
toothsurface. A high volume suction will be used. Cotton pellets will be changed to
a dry ones at this stage and the surface will be dried for 5s using the air syringe.
Adhesive system application: the adhesive system (Futurabond, VOCO) single dose
capsule will be applied over the surface to be sealed for 5 seconds using a
microbrush (ative movements along the fissures to ensure bond penetration). The bond
will be air thin dried for removal of solvent and excess material. The bond will be
lightcured for 10s before sealant placement.
Sealant application: a light-curing nano-hybrid fissure sealant material (Grandio
Seal; VOCO) will be applied using the applicator tip. A probe will be used to ensure
that the material is present in all fissures without any air bubbles.
Lightcuring: The material will be lightcured for 20 seconds. The material colour
will change to an opaque off white colour when exposed to light.
Check occlusion: After checking for premature contact points, if there is a need to
remove a excess of material, a superfine diamond bur or a silicone finishing point
can be used for adjustments.
Clinical variables such as children's age and gender, tooth position (upper/lower),
caries experience (DMFT/dmft), ICDAS score tooth surface (1/2/3), and children's behavior
during the procedure (Frankl scale) will be collected.
Evaluations
All children will be evaluated after 12 and 24 months by independent calibrated and blind
examiners for both primary (sealant retention) and secondary outcomes.
The presence of dental caries lesion will evaluated according to ICDAS criteria and
caries progression into dentine will be recorded. Sealant retention will be evaluated
according to the scoring system proposed by Oba et al. 2009: 0 (fully retained sealant);
1 (partially retained sealant) or 2 (absent sealant).