Alternative impression technique for edentulous anterior maxillary flabby tissue

This present study describes an impression technique to rehabilitate patients with flabby ridge in pre-maxilla through complete dentures. The proposed technique consists on the association of nondisplacive impression of the flabby area in the primary and functional impression. Therefore, a primary impression was performed with irreversible hydrocolloid with a dual impression. The impression material was removed at the region corresponding to the flabby area, characterizing a window, where a re-impression was conducted with the same material Research, Society and Development, v. 9, n. 10, e3269108621, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.8621 2 in a more fluid consistency. The functional impression was executed with a custom tray with perforations at the flabby area fabricated over a primary anatomic cast previously relieved. As a result, an anatomic impression with reduced compression over the flabby ridge was obtained. Moreover, an accentuated decrease of the mucosa compression was obtained through the material overflow from the custom tray perforations at the functional impression. After the acrylization of the prosthetic piece, a delimited box corresponding to the flabby mucosa in the prosthesis base was verified. Thus, it is concluded that the association of techniques proposed in this study reduced the compression over the flabby ridge area resulting in a complete denture copying anatomically the flabby area at rest. Thereby, in this case through a precise negative reproduction, a more favorable retention of the maxillary complete denture was obtained in patients with flabby ridge at the pre-maxillary area.

in a more fluid consistency. The functional impression was executed with a custom tray with perforations at the flabby area fabricated over a primary anatomic cast previously relieved. As a result, an anatomic impression with reduced compression over the flabby ridge was obtained. Moreover, an accentuated decrease of the mucosa compression was obtained through the material overflow from the custom tray perforations at the functional impression.
After the acrylization of the prosthetic piece, a delimited box corresponding to the flabby mucosa in the prosthesis base was verified. Thus, it is concluded that the association of techniques proposed in this study reduced the compression over the flabby ridge area resulting in a complete denture copying anatomically the flabby area at rest. Thereby, in this case through a precise negative reproduction, a more favorable retention of the maxillary complete denture was obtained in patients with flabby ridge at the pre-maxillary area.

Introduction
The presence of flabby mucosa at the alveolar maxillary ridge is common in people that use a maxillary complete denture associated to removable class I mandibular partial denture. Such situation is associated with the fact that the mandibular pillars dissipates occlusal loads that traumatizes the mucosa over the superior alveolar ridge (Pai, et al., 2014;Ahmed, 2017) and accelerates the process of reabsorption in this region, therefore, presenting an unretentive and unstable maxillary complete denture. In the presence of a flabby mucosa context, the hypermobility of these tissues during the impression can provoke a distortion of the original topography at the working cast, compromising the future prosthesis adaptation (Kulkarni, et al., 2018). Research, Society and Development, v. 9, n. 10, e3269108621, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.8621 4 Several alternative techniques of functional impressions are presented at the literature in an attempt to solve the problems regarding the ridge hyperplasia and flabbiness, providing a precise impression (Bansal, et al., 2014;Chakarvarty, et al., 2015;Rawat & Chadda, 2018).
Amongst the techniques, the mucocompressive and mucostatic impressions are highlighted, using tray modifications with windows or spacers, increasing the prosthesis support, retention and stability (Lynch & Allen, 2006;Gomma & El Mekawy, 2017). The one-step impression is a technique with perforations, where the custom tray is fabricated and little spaced perforations are made at the flabby area. Then, a peripheral sealing impression with lowfusion modelling compound and an impression with elastomeric material are performed (Shum & Pow, 2014). At Watson's "Window" adapted technique, a special slice similar to a window is performed in the custom tray at the flabby area, and grooves at the edge of the tray are made to increase the impression material mechanical adhesion. Thereafter, the impression is obtained with a two-consistency elastomeric material (Kazmi, et al., 2013). The Spacer's technique, described by Singh et al. (2014), uses a custom tray obtained through wax relief with double spacers at the region with excessive mobility tissue and posterior impression with a heavy-bodied elastomeric material. The spacer at the flabby area is removed, and then perforations are made followed by an impression with a light-bodied elastomeric material.
Despite the diversity encountered in the existent techniques, the impression of the maxillary alveolar ridge is still a challenge for the professionals. This is mainly a result from the distortions of the compressed areas during the impression. The cast's excess of relief, the small space between the perforation at the custom tray and the isolated application of these techniques are characteristics that could favor the impression at rest. As a differential, this present study proposes to describe a protocol of impression of the edentulous maxilla with anterior flabby tissue associating the techniques. Therefore, first a primary anatomic impression with double impression is conducted to avoid compression of the flabby region, followed by the functional impression using an individual tray with spaced holes at the region corresponding to the flabby area. It is expected, as an alternative hypothesis, a proposed simple and fast execution technique, capable to reduce the concentration of the force and distortion when the material is compressed against the tissue at the impression moment.

Methodology
The present study proposes to present a technique description to edentulous patient impression protocol with an anterior maxillary flabby tissue associating two impression Research, Society and Development, v. 9, n. 10, e3269108621, 2020 (CC BY 4  On intraoral clinical examination, it was possible to observe the flabby tissue of the anterior region of the maxilla. Figure 1 shows that the tissue was easily displaced with the aid of a dental instrument handle.   Figure 2A shows that after obtaining the anatomical mold, a window was made in the area corresponding to the anterior flabby tissue in the maxilla with a lecron instrument. In order to better copy this flaccid region, avoiding distortions, refinement was made with irreversible hydrocolloid with a softer consistency. Figure 2B shows the final mold obtained after performing this procedure.  Research, Society and Development, v. 9, n. 10, e3269108621, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.8621 7 Figure 3A shows the anatomical model obtained and the delimitation of the region to be relieved at the flabby ridge. In Figure 3B it is possible to observe the relief with wax in the region corresponding to the flabby tissue and palatine rugae.  Source: Authors Figure 4A shows the relief in the superior labial frenulum region. Perforations were performed in the region equivalent to the flabby anterior tissue to avoid distortions during the molding and copying of the tissues. In Figure 4B, after adjusting the custom tray and the peripheral seal impression, a functional impression with a zinc-enolic paste was performed.
7. Perform the beading with utility wax, 2 mm apart from the custom tray edge ( Figure 5A) and obtain the functional cast in dental plaster (Asfer, São Caetano do Sul, São Paulo, Brazil) ( Figure 5B). Research, Society and Development, v. 9, n. 10, e3269108621, 2020 (CC BY 4.0 After the polymerization of the material, the mold was removed and analyzed. Figure   5A shows the beading with utility wax. This procedure is performed to protect the edges and the reproduction of the functional model. Figure 5B shows the functional model obtained after removing the functional model from the mold.

Results and Discussion
As a result, the alternative hypothesis of this study was accepted and a simple and fast execution technique was obtained. Moreover, the reduction of the impression materials distortions was verified in the impression of the flabby ridge. The prosthesis retention, support and stability at the ridge are intrinsically dependent of a precise impression, especially before a flabby ridge (Figure 1). At the impression time, the fibrous tissues can be dislocated and suffer compression preventing the register and precise copy of the region; hence, the impression technique is important to minimize these inconveniences (Labban, 2018). In this sense, in order to eliminate this hypermobility and distortions during the impression, some mechanisms can be applied, such as the creation of windows, micro-perforations or orifices.
Such procedures decrease the pressure in the areas with flabby mucosa and reduce the alterations in position of the supporting tissues, which favors the distribution of forces over this region (Muthukumar, et al., 2012).
There are several techniques for flabby mucosa impression, one of which is the perforated impression technique. In the functional impression, an individual tray is fabricated and narrow spaced perforations are made in the area corresponding to the flabbiness.
Subsequently, an impression of the peripheral seal with low-fusing modelling compound and impression with an elastomeric material are performed (Shum & Pow, 2014). As a limitation, the insertion of an accurate impression force is a subjective process that varies between Research, Society and Development, v. 9, n. 10, e3269108621, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i10.8621 9 operators performing the procedure, which can result in discrepant and altered impressions. In addition, when these techniques are applied in isolated form there will be no possibility to compensate these alterations/distortions (Jain & Dhanraj, 2016).
Another technique capable of giving precision to the impression is the two-step window technique. Even though described in the literature, this technique shows difficulty in the uniform application and control of the fluid impression material. When the material is applied to the flabby tissues, it may flow through the window due to the gravity forces and maxillary positioning (Labban, 2018). Moreover, the impression obtained through this technique can result in a distorted impression. The impression material flow and displacement through the window can cause an unevenness (Muthukumar, et al., 2012). Therefore, before the aforementioned limitations and aiming to minimize them, the technique proposed in this present study is the association of the literature existent protocols. It is suggested that when these two techniques are added, the discrepancies related to the application in their isolated form can be decreased through the compensation of the association.
Initially, the window technique was performed at the primary impression, where an irreversible hydrocolloid material was used in the first step, followed by a window opening at the flabby ridge region, without its complete perforation (Figure 2A), avoiding the excessive material flowing due to the gravity. Thereafter, a refinement of the impression was made with a more fluid alginate ( Figure 2B), avoiding the limitations presented by the window's original technique.
In addition to this alternative primary impression, the use of a perforated tray technique was chosen for the functional impression of the flabby premaxilla. Despite its limitations described above, the use of perforated trays for the flabby ridge impression presents an excellent alternative, since at the compression of the material at the tray there is a reduction of pressure tendency from the palate to the periphery (Komiyama, et al., 2004). This indicates that the material will be able to flow beyond the central region, decreasing the forces concentration and distortions.
In regard to the perforated tray technique, the protocol applied in this study differed from the one described by Shum & Pow (2014), due to the hole size and the relief shape at the flabby ridge region. To avoid a sharp angle at the marked relief and posterior impression of the anatomy at the prosthesis base, the relief performed at the described technique was more smooth ( Figure 3B). Relief reduction compared to previously described techniques became possible due to its fabrication on a precise primary anatomical cast, obtained from an impression with reduced pressure at the flabby area. Thus, the border edge was obtained without the occurrence of sharp angles. In addition to this modification, the proposed technique modified the size and arrangement of the perforations, in which Shum & Pow (2014), performed holes with a 3mm diameter spaced from 1 to 3mm apart. In the present technique, the perforations were smaller (2mm diameter) and spaced 5mm apart ( Figure 4A).
The purpose of this alteration was to avoid an overflow of the impression material in order not to alter the impression of the anatomy.
From the combination of the techniques employed in this study, a delimited box of the flabby mucosa area was obtained at the acrylic prosthesis base, as observed in figure 6A, and perceived that the delimited box is not observed on previous acrylic prosthesis base ( Figure   6B). Source: Authors Figure 6A shows the base of the new complete denture properly copied, with welldelimited delimited spaces, showing the relevance of performing this technique for patients with flabby ridge. Figure 6B shows the patient's previous denture, with the absence of this delimited box.
The use of isolated techniques still favors the risk of obtaining excessive compressions. In conclusion, the combined use of the two pre-existing and modified techniques allowed a refinement in the impression of the flabby ridge area, which reduced the occurrence of bubbles and contributed to a smaller amount of distortions and a reliable copy of the flabby region. In addition, from the post-dam confection (figure 5A), it was possible to fabricate a prosthesis with greater stability, retention, precision and comfort for the patient.

Conclusion
The success of the prosthetic rehabilitation treatment is directly related to the performance of an adequate impression that provides the prosthesis support, retention, and stability. The professional must be capable to use an impression technique according to each patient profile, especially before flabby ridge cases.
Although this technique is important for obtaining well-fitted complete dentures, with support and stability, there is still a need for comparative studies with a higher level of scientific evidence that approaches the precision and efficiency of this technique in relation to others described in the literature. From this, it will be possible to assess patient satisfaction with the adaptation, acceptance, and use of new prostheses.