Dental Bleaching During Orthodontic Treatment with Aligners
Total Page:16
File Type:pdf, Size:1020Kb
CLINICAL RESEARCH Dental bleaching during orthodontic treatment with aligners Luca Levrini, MD, MS Department of Human Sciences, Innovation and Territory (DISUIT), University of Insubria, Italy Luigi Paracchini, PhD INGEO, Italy Renata Bakaj, DDS School of Orthodontics, University of Insubria, Italy Andrada Diaconu, DH Private Practice Sofia Cortese, DH Private Practice Correspondence to: Prof Luca Levrini Department of Human Sciences, Innovation and Territory (DISUIT), University of Insubria, Via Sant’Abbondio, 12, 22100, Como, Italy; Tel: +39 31 2384311; Email: [email protected] 44 | The International Journal of Esthetic Dentistry | Volume 15 | Number 1 | Spring 2020 LEVRINI ET AL Abstract compared with that on teeth 31 and 42 (study teeth, without reservoirs). Objective: The present study was undertaken to de- Results: The FEA results showed that the optimal gel termine the tooth whitening effectiveness of trays distribution is reached when 2 mm3 of gel is applied to with no reservoirs (Invisalign aligners or Vivera retain- the center of the vestibular face of the tooth in the ers used as bleaching trays), initially with a finite ele- tray. As regards the clinical study, there were no rele- ment analysis (FEA) and subsequently with a clinical vant differences of whitening effectiveness between study using spectrophotometry. the teeth with reservoirs and those without. In both Materials and methods: The FEA technique was used cases, the whitening was effective and the patients to determine the ideal distribution of bleaching gel be- were completely satisfied with the results. tween teeth and aligners in vitro. Three sample areas Conclusions: The advantages for patients to receive of gel application on the maxillary central incisors (the dental bleaching during orthodontic treatment with incisal edge, the middle part, and the gingival edge) aligners are evident. The procedure is not time con- were analyzed. Spectrophotometry was used to as- suming and requires less financial expense. Further certain the clinical effectiveness of the bleaching gel clinical studies are required to assess the effectiveness as it related to the results of the FEA. More specifically, of the procedure. the chromatic variation obtained by the bleaching gel on teeth 41 and 32 (control teeth, with reservoirs) was (Int J Esthet Dent 2020;15:44–54) The International Journal of Esthetic Dentistry | Volume 15 | Number 1 | Spring 2020 | 45 CLINICAL RESEARCH Introduction ing gel sealed inside, thus preventing gum irritation and saliva mixing with the gel. The Dental bleaching is often performed during most common disadvantages of this pro- orthodontic treatment as an ancillary pro- cedure are teeth and gum sensitivity due to cedure to obtain better esthetic results. Ac- an uncontrolled and extended treatment cording to the literature, almost 90% of pa- performed autonomously by patients who tients request tooth whitening, and 76% of may desire instant results. orthodontists recommend whitening pro- The most frequently used products are cedures.1 However, only one-third (33%) of carbamide peroxide (10% or 16%) and hy- orthodontists provide in-office whitening, drogen peroxide (10%). Recently, gum and whereas nearly two-thirds (66%) refer pa- teeth sensitivity has been better managed tients to other dental practitioners.1 thanks to thicker peroxide gels that do not It is more common today for tooth soak into the tooth as much as previous whitening to be performed as the ultimate gels, and the use of desensitizers such as end-of-treatment step to obtain optimal es- potassium nitrate and fluoride. Many den- thetic results. However, this is time consum- tists therefore recommend tooth whitening ing and affects the duration of the therapy, home maintenance with a lower-percent- consequently making it more expensive for age bleach that can be kept on the teeth for the patient (additional customized trays longer periods of time. need to be purchased to perform dental Nowadays, progressive orthodontic align- whitening after an orthodontic therapy). On ers are becoming increasingly popular the other hand, using orthodontic aligners among orthodontists and patients. Even or retainers as bleaching trays saves time though in the past aligners were mainly compared with undertaking additional used on adult patients seeking an esthetic bleaching treatment after orthodontic ther- solution for mild malocclusions, they have apy. Also, patients are only charged for the recently become more efficient and can bleaching gel, without having to support ex- also be used for major malocclusions. It tra costs, and the entire procedure out- therefore seems opportune to integrate comes are monitored by the clinician during dental bleaching and aligner treatment op- the scheduled orthodontic visits. tions in the process of care, avoiding the Bleaching can be performed using a need to purchase additional customized wide variety of methods, including in-office trays. Dental bleaching could be performed bleaching and at-home bleaching. The for- on patients simply by using their custom- mer procedure provides fast and immedi- ized aligners without attachments during ately apparent results and takes place under the treatment, instead of buying extra ones carefully monitored conditions that allow for bleaching use only. Additionally, it would for the safe and pain-free use of a relatively also be possible for patients to use their high concentration of bleaching gel. On the customized final retainers (Essix or Vivera) other hand, at-home bleaching is performed as bleaching trays after fixed orthodontics. with a low dosage of bleaching agents by There is no evidence to show that com- patients at home, even though it is neces- monly used trays with reservoirs are better sary for dentists to carefully monitor the than orthodontic aligners or retainers for condition of both the teeth and the gum- tooth whitening purposes. Some reports in line. For this purpose, vinyl trays containing the literature2-4 consider reservoirs to be un- bleaching gel reservoirs are custom fabri- necessary, despite the fact that they are the cated. The objective is to keep the bleach- most common bleaching trays used by pa- 46 | The International Journal of Esthetic Dentistry | Volume 15 | Number 1 | Spring 2020 LEVRINI ET AL Figs 1 and 2 3D models from patients achieved using the iTero Element intraoral scanner. tients at home. It must be stressed that tigate the best location for gel in the trays these reports do not describe a method without reservoirs in order to obtain optimal protocol and give no indication of the type gel distribution, taking into consideration of gel to use (quantity and physical charac- the tray material and the gel type. The sec- teristics), its placement inside the trays, and ond was a clinical study focusing on the dif- the physical features of the trays them- ferences in effectiveness between gold selves. standard bleaching trays with reservoirs and If the method of the present study proves trays without reservoirs (Invisalign aligners effective and safe for patients, aligner treat- or Vivera retainers). ment could represent an integrative pro- cedure that combines functionality and es- Materials and methods thetics, ie, patients could use aligners to combine the concepts of straight teeth and Finite element analysis (FEA) white teeth, without extra costs or addition- al treatment time. There should, however, A FEA system was used as a virtual simula- be a focus on the damage that the acidic tion of the chemical and physical behavior bleaching gel might cause to the gums,5 al- of gel (responsible for tooth whitening) though it could be argued that such a tem- placed inside a transparent system (such as porary acidic condition is no more detri- Invisalign aligners or Vivera retainers) be- mental than habitual, long-term poor oral tween the aligners/retainers and the teeth. hygiene or a highly acidic diet. Specific FEA is a type of computer program that uses studies on this aspect need to be conduct- the finite element method to analyze a ma- ed.6 Furthermore, some clinicians believe terial or object to determine how stresses that the contact of the acid on the aligner will affect the material or design. The analy- trays can somehow reduce its efficiency. sis is done by creating a mesh of points in In view of these considerations, and as- the shape of the object that contains infor- suming that active aligners or retainers are mation about the material and the object at useful tools to manage tooth whitening in each point of analysis. For this purpose, a orthodontic patients, two parallel proced- simplified system was devised, taking into ures were performed in this study. The first consideration only eight teeth in the maxilla procedure was a virtual fluid dynamic study on which a three-dimensional (3D) model with a finite element analysis (FEA) to inves- FEA was conducted. For a further refine- The International Journal of Esthetic Dentistry | Volume 15 | Number 1 | Spring 2020 | 47 CLINICAL RESEARCH ment of the FEA, the 3D model of gel, tray, and maxilla was simplified to consider the central incisors only. The simulation con- cerned three different areas of the teeth: the occlusal edge, the middle, and the gin- gival edge. First, an intraoral scanner (iTero Element) was used to obtain a 3D file of the patient’s impressions. Then, the solid to layer (STL) file, elaborated from the iTero, was pro- 0.000 3.500 7.000 (mm) 1.7500 5.250 cessed by Geomagic (3D Systems) to obtain a 3D file of the dental impressions and a 3D Fig 3 3D solid mesh used for the FEA considering, in particular, a section of the file of the teeth (Figs 1 and 2). The inner sur- central incisor. faces of the tooth tray had an offset of 1 mm compared with the outer surfaces of the pa- tient impressions (Fig 3). Once a 3D file from the scanned two-dimensional (2D) surfaces of the teeth was obtained, a series of as- semblies and matchings were recreated through SolidWorks 2014 SP4 (Dassault Sys- tèmes) in Windows 7 SP1, in order to reach the final phase of the FEA.