Adhesive system containing Bioglass 45S5 particles in teeth affected by molar-incisor hypomineralization and quality of life impact: study protocol for a randomized clinical trial

Abstract

Background

Molar-incisor hypomineralization (MIH) is a systemic condition characterized by a qualitative defect in the dental enamel. It primarily affects the first permanent molars and is often associated with the permanent incisors. Resin restorations in MIH-affected teeth consistently show worse results than those in normal teeth because of the ultrastructure of hypomineralized enamel, which compromises adhesion. The incorporation of bioactive particles into adhesives is a promising option for inducing remineralization. This study protocol describes a randomized clinical trial evaluating restorative treatment using an adhesive system containing 45S5 bioactive glass for MIH-affected teeth.

Methods

Restorations will be performed on the upper or lower first permanent molars in children with MIH aged 6–12 years. The inclusion criteria will include MIH teeth with post-eruptive enamel fractures that compromise the middle third of the dentin, with at least two surfaces of hypomineralized enamel near the cavity, without caries, pulpal, or periradicular involvement. Before treatment, children will complete the Child Perceptions Questionnaire 8–10 and 11–14 (CPQ8–10 and CPQ11–14). The teeth will be divided into two groups: a control group (commercial self-etching adhesive system: Clearfil SE Bond (CF) Primer + Bond) and an experimental group (CF Primer + experimental Bond using 10% 45S5 bioglass [Bond 45S5 10%]). Restorations will be made using composite resin, and quality will be assessed using digital radiographs (interproximal and periapical), intraoral photographs, and epoxy resin replicas. Clinical evaluation of the restorations will be performed immediately following the procedure (baseline) and after 1, 3, 6, and 12 months using the World Dental Federation (FDI) criteria. The impact of the treatment on the quality of life will be assessed after 3, 6, and 12 months through the re-administration of CPQ8–10 and CPQ11–14.

Discussion

45S5 bioactive glass is capable of enhancing the effect of materials on bone and dental structures, promoting remineralization. The results of this study may aid in the clinical management of patients with MIH, given the challenges of treating sensitive and compromised teeth and the difficulty in achieving long-term restorative success while addressing the individual patient needs.

Trial registration

Rebec, U1111-1259-1738. Registered on January 10, 2021.

Administrative information

Title {1}	Adhesive system containing Bioglass 45S5 particles in teeth affected by molar-incisor hypomineralization and quality of life impact: study protocol for a randomized clinical trial
Trial Registration {2a and 2b}	Rebec, U1111-1259-1738. https://ensaiosclinicos.gov.br/rg/RBR-9wyw779
Protocol version {3}	10.01.21 Version 1.0
Funding {4}	Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES (88887.799882/2022-00); Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq (422197/2021-1); Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão – FAPEMA (02355/21)
Author details {5a}	Kamila Nogueira Borges da Costa1; Nicole Paiva Veras1; Ceci Nunes Carvalho2; José Roberto de Oliveira Bauer3; Alessandro Dourado Loguercio4; Andres Felipe Millan Cardenas3; Fabiana Suelen Figuerêdo de Siqueira3; Meire Coelho Ferreira2. 1PhD student in dentistry, UNICEUMA, São Luís, Brazil. 2PhD and professor of postgraduate studies in dentistry, UNICEUMA, São Luís, Brazil. 3PhD and professor of postgraduate studies in dentistry, UFMA, São Luís, Brazil. 4PhD and professor of postgraduate studies in dentistry, UEPG, Ponta Grossa, Brazil.
Name and contact information for the trial sponsor {5b}	Postgraduate Program of Dentistry, Ceuma University (UNICEUMA). R. Anapurus, 1,65075-120. São Luís, Maranhão, Brazil. Tel: +55 98 4020-7525.
Role of sponsor {5c}	The sponsor and funders of the study do not play a role in the design, collection, management, analysis, and interpretation of data; elaboration of the report; or decision to submit the report for publication, including authority over these activities.
Composition of the coordinating center and trial steering committee {5d}	Throughout the study, a steering committee made up of all authors involved will be present. During the trial, this group will meet as necessary to discuss the progress of the trial.

Introduction

Background and rationale {6a}

Molar-incisor hypomineralization (MIH), a condition that affects one or more first permanent molars mainly in the occlusal thirds of the crown, is frequently associated with permanent incisors, mainly in the incisal third of the labial surface [1]. If changes are present only in the incisors, this does not meet the definition of MIH [2].

MIH is visually identified by changes in the translucency of the enamel, defined by areas with white, cream, yellow, or brown color. Yellow or brown lesions, which are more porous and have a lower mineral content than white lesions, are more severe [3, 4]. Therefore, large clinical variations in the severity of MIH can be observed. The mild form is characterized by opacities ranging in color from white to brown without loss of the enamel structure due to fractures [5]. Severe lesions are those with post-eruptive structural loss due to fragile and porous enamel [6].

A recent study in Brazil on 407 children aged 7–14 years found that the prevalence of MIH is 13.48% (95% confidence interval (CI), 8.66%–18.31%) [7]. The etiology of MIH has not yet been elucidated. Several possible etiologies have been proposed. In the prenatal phase, the cited causes include smoking and maternal illness during pregnancy. In the perinatal phase, hypotheses have been made regarding premature birth, low birth weight associated with hypoxia, and prolonged birth or cesarean section [8]. Respiratory and early childhood diseases, medications, and breastfeeding during the postnatal period have also been proposed as etiological factors [9, 10]. Genetic polymorphisms may also be associated with this condition [11].

The enamel of teeth with MIH is characterized by a disarray of crystals, porous structure, histologically less distinct prism sheath, and low mineral content [12, 13]. Thus, patients with hypomineralized enamel present with reduced mechanical properties of hardness and modulus of elasticity, which are related to structural loss and greater risk of rapid development of cavities and restoration failure [14].

Studies have assessed the impact of MIH on quality of life using the Child Perception Questionnaire (CPQ). One of these studies used the CPQ8–10 in children aged 8–10 years with mild MIH injuries, and another study used the CPQ11–14 in pre-adolescents aged 11–14 years with severe MIH injuries. Both studies found that the participants had a higher prevalence of negative effects because of oral symptoms and functional limitations [15, 16]. A third study on pre-adolescents aged 11 and 12 years revealed a negative impact on the social well-being domain [17].

The clinical approach to MIH presents a major challenge because of the sensitivity that can accompany compromised teeth, difficulty in achieving long-term success with restorative procedures, and individual needs of each patient. Various restorative treatment options are used for the clinical management of these teeth, including steel crowns, composite resins, and glass ionomer cements [18, 19].

Resin restorations of teeth with MIH have worse results than those of teeth without structural defects [20]. This is due to aspects related to the ultrastructure of hypomineralized enamel, which compromise adhesion [21]. Different approaches have been proposed to improve the clinical performance of restorations in molars affected by MIH [19, 22]. However, to date, no studies have used bioactive materials.

Restorative materials with bioactive particles have been used in dentistry because they can stimulate remineralization of the tooth structure [23] and increase the durability of the resin-dentin interface [24] by increasing the modulus of elasticity and hardness of dentin collagen. Therefore, the incorporation of bioactive particles into adhesives has been reported as a promising option to induce remineralization and the formation of “bioactive dental structures” [23,24,25,26].

Objectives {7}

The overall aim of the present study is to compare the clinical parameters of composite resin restorations after the use of adhesive systems with and without 45S5 bioglass particles in the first permanent molars affected by MIH. The secondary objectives are evaluating the longevity of composite resin restorations after using adhesive systems containing 0% and 10% 45S5 bioglass particles on first permanent molars affected by MIH for 3, 6, and 12 months and comparing the effects on the quality of life before and 3, 6, and 12 months after treatment of the first permanent molars affected by MIH.

Trial design {8}

This study was initiated in April 2021 and is expected to be completed by November 2025, with follow-ups at 1, 3, 6, and 12 months. This is a randomized clinical trial with up to 1 year of follow-up. Participants will be divided into two groups: a control group (commercial self-etching adhesive system: Primer + Bond of Clearfil SE Bond (CF)) and an experimental group (primer of CF + experimental bond with Bioglass 45S5 at 10% (Bond 45S5 10%)). The allocation of participants will follow an order of randomly generated sequences. The full protocol adheres to the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) (Fig. 1) [27].

Fig. 1

SPIRIT

Methods: participants, interventions, and outcomes

Study setting {9}

This study is carried out at the Pediatric Dentistry Clinic School of CEUMA University, São Luís, Maranhão, Brazil. Patients who do not meet the criteria are referred for treatment by other professionals. No amount is charged to those involved in the processing of the study data. All the participants will receive oral hygiene instructions before undergoing dental treatment.

Eligibility criteria {10}

The following are the inclusion and exclusion criteria:

• 1. Children with good general health and acceptable levels of oral hygiene according to the simplified oral hygiene index [28].

• 2. Children must have at least one tooth diagnosed with MIH, with a post-eruptive enamel fracture compromising the middle third of the dentin, without caries, pulpal, or periradicular involvement.

• 3. The cavity margin cannot involve less than 50% of the enamel [29] with at least two surfaces with hypomineralized cream/yellow/brown enamel close to the cavity margin.

• 4. Participants who present with enamel malformations associated with syndromes, amelogenesis imperfecta, first permanent molars with completely destroyed crowns, dental fluorosis, or erosions will be excluded.

• 5. Individuals with poor oral hygiene, those using fixed orthodontic appliances, and those with gastroesophageal reflux will be excluded.

Who will take informed consent or assent? {26a}

The main researcher will be responsible for presenting the parents and children eligible for the study with informed consent or assent form explaining the nature and purpose of the study.

Consent or assent: ancillary studies {26b}

No additional consent is required because ancillary studies will not be carried out.

Interventions

Explanation for the choice of comparators {6b}

Using self-etching adhesives is a restorative treatment strategy for teeth affected by MIH. These adhesives may have good clinical survival in restorations of molars affected by MIH when a conservative cavity preparation is performed [22]. Clearfil SE Bond is considered effective in bonding to dentin owing to the presence of the monomer 10-MDP (methacryloyloxydecyl dihydrogen phosphate) in its composition, which promotes a stable and long-lasting hybrid layer at the resin-dentin interface [30]. Therefore, their use is justified for comparison with the experimental adhesive. The adhesive system will be used according to the manufacturer's instructions.

Intervention description {11a}

For each restoration, the types of tooth (upper/lower molar) and cavity (number of surfaces restored) will be recorded. The operator who will conduct all restorative procedures will be previously trained by an experienced professor, who is a specialist in pediatric/restorative dentistry with more than 5 years of experience in clinical research. All patients will receive prophylaxis before undergoing the restorative procedure.

As there is a possibility of tooth sensitivity getting compromised by MIH and difficulty in analgesia through anesthesia, ibuprofen will be prescribed 1 day before (three doses, 8/8 h) and 1 h before the intervention [31]. The operator will anesthetize the patient and perform absolute isolation. The design of the cavity will be restricted to the elimination of softened dentin tissue with a dental spoon and all enamel compromised by a cream/yellow/brown stain around the cavity without dentin support. No base/lining material will be administered to the cavities. A matrix system (Palodent, Denstsply Caulk, Millford, DE, USA) will be used for class II cavity restorations. However, a semi-circumferential matrix system will be used when a good fit is not obtained using another matrix system.

Two adhesive systems will be used: Clearfil SE Bond (Kuraray Noritake, Tokyo, Japan) and Clearfil SE Bond with 10% 45S5 bioglass particles [added to the bond of the adhesive system]. The adhesives will be administered according to the manufacturer’s instructions, and the teeth will be restored using the composite resin Z350 (3M Oral Care, Barueri, SP, Brazil).

The operator will adapt the composite resin using a flat or elliptical face condenser and light-cures each increment for 20 s with a Radii-Cal CX (SDI, Melbourne, Australia) light cure unit at 1200 mW/cm². The tip of the light-curing device will be placed as close as possible to the occlusal surface of the teeth, and the light intensity will be checked daily. Occlusal adjustments and polishing will be performed using diamond burs (KG Sorensen, Serra, ES, Brazil) and polishing tips (KG Sorensen, Serra, ES, Brazil).

Immediately after the restorative procedure and for three consecutive weeks, fluoride varnish (Duraphat, Colgate-Palmolive, USA) will be administered under relative isolation with the aid of a microbrush (KG Sorensen) around the restoration, but without contact with the tooth-restoration interface.

Digital radiographs (interproximal and periapical), intraoral photographs, and moldings with additional silicone will be taken to obtain replicas in epoxy resin to assess the immediate quality and 1 year after the restorations.

Criteria for discontinuing or modifying allocated interventions {11b}

Patients may discontinue participation at any time. Patients will be excluded in the following cases: unacceptable level of oral hygiene, lack of regular appointments, or in cases of spontaneous pain.

Strategies to improve adherence to interventions {11c}

Parents/guardians will be informed about the importance of treating teeth affected by MIH to avoid further destruction of the remaining dental structure, and consequently, possible tooth loss. Bearing in mind that tooth loss compromises occlusion, affecting chewing, speech, and the quality of life of the affected child.

Relevant concomitant care permitted or prohibited during the trial {11 d}

No other intervention will be allowed for the teeth being treated during the entire follow-up period. The teeth outside the study area may be treated by other professionals.

Provisions for post-trial care {30}

Participants will continue attending the Pediatric Dentistry Clinic School at Ceuma University for clinical care until the end of the study.

Outcomes {12}

Primary outcomes

The retention of the restoration will be determined using the Federation Dental International (FDI) index [32] and will be administered immediately after the restorative procedure and at 1, 3, 6, and 12 months.

Secondary outcomes

Impact on quality of life will be determined using the CPQ8–10 and CPQ11–14 instruments administered before and 3, 6, and 12 months after treatment for first permanent molars affected by MIH.

Participant timeline {13}

The participant timeline is outlined in Table 1.

Table 1 Participants visits and procedures

Sample size {14}

Sample calculations were performed using an online software [http://www.sealedenvelope.com]. This was based on a study conducted on patients with MIH, whose restoration retention rate was 70% after 18 months [22], with a confidence level of 95%, power of 80%, and bilateral test. The minimum sample size required to detect a 25% difference between the tested groups was 33 teeth with MIH in each group.

Recruitment {15}

Participants will be recruited through teaching clinics at Ceuma University and other higher education institutions, as well as social media and public and private schools.

Assignment of interventions: allocation

Allocation sequence generation {16a}

The random allocation sequence will be generated by a team member not involved in the restorative procedure or treatment evaluation using the software available at http://www.sealedenvelope.com. Details of the interventions will be recorded on cards kept in sealed opaque envelopes and numbered sequentially.

Allocation concealment mechanism {16b}

The allocation concealment mechanism will be carried out by implementing a random sequence in the envelopes. The outside of the envelope will contain the block identifier, sequence number within the block, and generated code, whereas the inside of the envelope will contain the treatment corresponding to the generated code. The envelope will be sealed.

Allocation implementation {16c}

When a new participant is enrolled in the survey, an envelope following the sequence of envelopes with random numbers will be assigned to them, and their name will be written on the envelope. The envelope will be opened immediately before the restorative procedure to ensure concealment of the random sequence and avoid selection bias.

Assignment of interventions: blinding

Who will be blinded {17a}

The operator will be blinded to the administered adhesive (the labels of the adhesive systems will be masked), the examiner will be blinded to the evaluation of the restorations, participants will not be aware of the adhesive administered to each tooth, and the statistician will be blinded to the study groups.

Procedure for unblinding if needed {17b}

In case of symptoms related to the study intervention, disclosure will be made by the investigator. Information on the material used for each tooth will be present in each patient's clinical records. Once disclosure is made, the intervention will be discontinued.

Data collection and management

Data collection plan {18a}

The researchers involved in the study will be trained for MIH and the questionnaires to be administered. A lesson will be given on MIH and the research instruments. Then, images of MIH lesions will be projected, and the researchers will diagnose the lesions, with one assessment carried out immediately after the images are projected and another after 7 days.

For the selection of participants, a clinical examination will be carried out using a mouth mirror, ball tip probe (OMS-621, Trinity®, Campo Mourão, PR, Brazil) to remove bacterial biofilm and food debris on the tooth surface, and millimeter periodontal probe (satin steel cable nº 6, Hu-Friedy, Chicago, IL, USA) to measure the depth of the MIH lesion.

Teeth with MIH will be selected based on the European Association of Pediatric Dentistry (EAPD) criteria [33]. Additionally, interproximal and periapical digital radiographs will be taken to confirm the depth of the MIH lesion in the dentin and to rule out pulpal or periradicular involvement.

To assess sensitivity, air from the triple syringe will be used for 3 s, perpendicular to the surface of the dental crown, at a distance of approximately 2 mm under relative isolation. The neighboring teeth will be isolated using a cotton roll to avoid false-positive diagnoses. Children will be instructed to raise their left hand if they experience pain [34]. Then, the magnitude of pain will be measured using the Wong-Baker Faces scale [35] (Fig. 2) containing five facial expressions, with “No pain” on the left end and “Worst possible pain” on the right end. The response categories are 0, no pain; 1–2, mild pain; 3, moderate pain; 4, severe pain; and 5, worst possible pain.

Fig. 2

Wong-Baker faces pain rating scale

A questionnaire to collect socioeconomic information; health aspects in the pre-, peri-, and postnatal periods; and aspects related to teeth with MIH will be administered to the parents/guardians.

The CPQ 8–10 and 11–14 will be administered in an interview format before and 3, 6, and 12 months after treatment. The Portuguese version of the CPQ 8–10 was validated by Martins et al. [36]. This instrument contains 25 items divided into four domains: oral symptoms (five items), functional limitations (five items), emotional well-being (five items), and social well-being (10 items). The response categories for each item are classified on a scale to record how often an event has occurred in the previous 4 weeks: 0, not at all; 1, once or twice; 2, a few times; 3, many times; and 4, every day or almost every day. The scores of the items are summed, and the total score can range from 0 (no impact of oral condition on quality of life) to 100 (maximum impact of oral condition on quality of life).

The short version of the CPQ 11–14 was validated in Brazilian Portuguese by Torres et al. [37]. This instrument contains 16 questions divided into four domains: oral symptoms (four items), functional limitations (four items), emotional well-being (four items), and social well-being (four items). The response categories for each item are classified on a scale to record how often an event had occurred in the last 3 months: 0, never; 1, once or twice; 2, sometimes; 3, often; and 4, every day or almost every day. The scores of the items are summed, and the total score can vary from 0 (no impact of oral condition on quality of life) to 64 (maximum impact of oral condition on quality of life).

Moldings with added silicone (Futura AD, DFL, Rio de Janeiro, RJ, Brazil) will be obtained immediately after the restorative procedure and at 3, 6, and 12 months. These moldings will be cast in epoxy resin (Redelease, São Paulo, SP, Brazil) at intervals of up to 14 days. The models made of transparent epoxy resin will be sprayed with titanium dioxide powder (3M ESPE, Saint Paul, MN, USA). The replicas will be scanned using the Lava™ Chairside Oral Scanner C.O.S (3M ESPE, Saint Paul, MN, USA) and analyzed using the Geometric Studio 12 software (3D Systems, Rock Hill, SC, USA).

Two examiners who are not involved in the restorative procedure will evaluate the restorations using the FDI criteria [32] immediately after the restorative procedure (baseline) and after 1 3, 6, and 12 months. The following aspects will be evaluated: fracture, adaptation/marginal, discoloration, wear, interproximal radiographic examination (evaluating the radiopacity of the restoration, presence of pathology, and excess material), color stability, translucency, and post-operative sensitivity (face scale). These variables will be classified according to the FDI criteria into the following scores: clinically excellent/very good, clinically good, clinically sufficient/satisfactory, clinically unsatisfactory but can be repaired, clinically poor, and require replacement.

The forms created to record the data will be available in an online repository.

Plans to promote participant retention and complete follow-up {18b}

Oral hygiene guidelines will be provided during follow-up. The participants will be encouraged to maintain their visits through phone calls and text messages. Furthermore, if the child requires any other dental treatment, they will receive the necessary information in addition to a referral for treatment.

Data management {19}

Data will be collected using forms constructed for this purpose and transferred to a database through coding. To improve data quality, some of the recorded data will be checked for validity. The data will be stored in an institutional directory.

Confidentiality {27}

Confidentially will be guaranteed regarding child identification and the information obtained through their participation. Access to the collected data will be granted only to the members of the research group.

Plans for collection, laboratory evaluation, and storage of biological specimens for genetic or molecular analysis in the current trial/future use [33]

No biological specimens will be collected for genetic or molecular analyses in this study.

Statistical methods

Statistical methods for primary and secondary outcomes {20a}

Data will be subjected to descriptive and inferential analyses at a significance level of 5%. All analyses will be performed using the Statistical Package for the Social Sciences (SPSS, version 21.0, IBM Corp, Armonk, NY, USA).

Primary outcome

Restoration retention will be measured using frequency, and bivariate analyses will be used for inter- and intragroup comparisons.

Secondary outcomes

The impact of treatment on quality of life will be measured using averages, and bivariate analyses will be used for inter- and intragroup comparisons.

Interim analyses {21b}

Interim analysis will not be performed for the primary endpoint.

Methods for additional analyses (e.g., subgroup analyses) {20b}

No additional analyses will be performed in the study.

Methods in analysis to handle protocol non-adherence and any statistical methods to handle missing data {20c}

Mean imputation will be performed for missing values in the data analysis. Missing values will be replaced with the average of the values present in the same variable.

Plans to give access to the full protocol, participant-level data, and statistical code {31c}

The data will be available, if necessary, with some restrictions on purpose and data protection.

Oversight and monitoring

Composition of the coordinating center and trial steering committee {5 d}

Throughout the study, there will be a steering committee comprising all authors involved. During the trial, the group will meet as necessary to discuss the progress of the trial.

Composition of the data monitoring committee, its role, and reporting structure {21a}

A data monitoring committee will be established to discuss the arrangement of data in the database and possible variables that can be created based on the original variables.

Adverse event reporting and harms {22}

Monitoring participant conditions during the trial will be carried out to assess, report, and enable appropriate management of adverse events, such as spontaneous post-operative pain.

Frequency and plans for auditing trial conduct {23}

Trial auditing will not be carried out.

Plans for communicating important protocol amendments to relevant parties (e.g., trial participants, ethical committees) {25}

Amendments will be communicated to the study participants, and changes will be made on the Rebec Platform (ensaiosclinicos.gov.br) and Research Ethics Committee at Ceuma University.

Dissemination policy: trial results {31a}

A randomized clinical trial will be published in an international peer-reviewed journal reporting the performance of the restorative material and impact of treatment on participant quality of life at assessment times of 1, 3, 6, and 12 months.

Discussion

This clinical trial will evaluate the retention rate of adhesive restorations made using two self-etching adhesive systems in first permanent molars affected by severe MIH and will assess the impact of this treatment on the quality of life of the participants involved.

Treatments for MIH vary depending on the severity of the injury [18]. Restorative treatment is indicated in cases of severe MIH with structural loss of enamel/dentin or associated carious lesions [5]. However, restorative treatment of first molars affected by MIH is challenging because of the altered structure of the enamel and dentin, which affects the adhesion of dental materials. Therefore, these restorations have a higher risk of failure and fracture [38, 39]. In dental practice, having a wide range of restoration options is important even for teeth that are difficult to restore.

45S5 bioglass is a bioactive material that has been used in dentistry to improve the effect of materials on bone and dental structures and is capable of inducing remineralization [40] and releasing calcium and phosphate, consequently increasing the hardness of the remaining dentin structure. Furthermore, its high pH can inhibit bacterial growth and proliferation of collagen-denaturing enzymes. Therefore, its association with restorative materials is expected to promote greater stability at the adhesive interface [41].

Children aged 6–12 years who met the eligibility criteria will participate in the study. No amount will be charged for the treatment of participants. The intervention should restore functionality, considering that the teeth should show structural loss upon initial examination. Furthermore, the treatment involves mechanisms that aim to reduce dentin sensitivity through the restoration and administration of fluoride varnishes. Therefore, the intervention effect will be evaluated on everyday aspects of these children's lives. Dental defects, such as MIH, can negatively affect social relationships and daily activities.

Visits to the office will be frequent, which may cause resistance to the regularity of patient appointments. However, contact through calls and messages, encouragement regarding correct oral hygiene, and treatment results are believed to be capable of retaining participants in the study. Furthermore, this type of intervention presents a low overall risk for those involved.

Trial status

Protocol version 1.0, from January 2021. The recruitment period began in April 2021 and is scheduled for completion in November 2025.