**1. Introduction**

The use of dental implants has become a common treatment modality and an important component of modern dentistry [1]. In many clinical situations, the edentulous areas to be rehabilitated do not offer adequate bone volume for implant placement; this may be due to different causes, such as the presence of anatomical structures that limit it (maxillary sinuses, presence of nerves or vessels, etc.) due to early bone atrophy and the traumatic extraction of a tooth or periodontal disease [2,3]. Tooth extraction is associated with the remodeling of the alveolar process and results in changes, both structural and dimensional, with horizontal losses of up to 29%–63% and vertical losses of 11%–22% at 6 months after tooth extraction [4,5].

For such defects, guided bone regeneration procedures before or in combination with implant placement are necessary [6]. These procedures are based on the use of different types of graft materials and membranes. The bone substitute must be osteoconductive, to act as a scaffold maintaining three-dimensional support during bone healing, and also osteoinductive, stimulating bone formation; the membranes act as a barrier and seal the area to be regenerated to prevent the ingrowth of soft tissue [7,8].

**Citation:** Torrejon-Moya, A.; Apalimova, A.; González-Navarro, B.; Zaera-Le Gal, R.; Marí-Roig, A.; López-López, J. Calcium Sulfate in Implantology (Biphasic Calcium Sul-Fate/Hydroxyapatite, BCS/HA, Bond Apatite®): Review of the Literature and Case Reports. *Coatings* **2022**, *12*, 1350. https://doi.org/ 10.3390/coatings12091350

Academic Editor: Jun-Beom Park

Received: 14 August 2022 Accepted: 12 September 2022 Published: 16 September 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Historically, the most widely used grafting material was autologous bone, both extraoral and intraoral [9,10]; however, obtaining autogenous bone has several negative aspects, such as increased morbidity for the patient, limited supply, and increased duration of the intervention [11,12].

We currently have different types of bone graft materials for dental applications. Depending on the origin, they are classified as autografts, allografts, xenografts, or alloplastic grafts and can be found in the form of granules, putties, gels, and pastes, or blocks [13].

One of these alloplastic grafts is calcium sulfate, which is a common bone substitute and with a history of clinical use spanning more than 100 years, the first report of its use as a bone graft material was by the German physician Dreesman in 1892 when it was used as a treatment to seal bone defects in the long bones of eight patients with tuberculosis, according to Pelteier et al., in their work from 1957 [14]. This material is highly biocompatible and osteoconductive, undergoing practically complete resorption in vivo, and can be used as a vehicle to administer antibiotics, pharmacological agents, and growth factors [14,15].

Therefore, calcium sulfate, which is a bioactive material that produces the release of abundant calcium ions, is used as a synthetic graft material in orthopedics, plastic surgery, oncological surgery, and dentistry, and it has been used in a variety of clinical applications, such as the repair of periodontal defects, the treatment of osteomyelitis, and maxillary sinus augmentation, and as a complement to the placement of dental implants [16–19].

However, despite its many indications, it has some deficiencies that have prevented its daily use in dentistry, highlighting its rapid and complete resorption and hardening difficulties in the presence of saliva and bleeding. In 2010, Dr. Amos Yahav presented Bond Apatite® (Augma Biomaterials Ltd., Caesara Industrial Park, Israel & Microdent, Santa Eulàlia de Ronçana, Barcelona, Spain), a biphasic calcium sulfate that has proven to be more stable and with better properties than classic calcium sulfate [20,21]. It is a bone graft material composed of 2/3 biphasic calcium sulfate and 1/3 synthetic hydroxyapatite of different granulometry. Being the only one available, it is made of calcium sulfate and having the addition of hydroxyapatite. Calcium sulfate is reabsorbed and it is the hydroxyapatite particles that maintain volume during the process of new bone formation [22–24].

According to the study carried out by Yahav et al. [24], the addition of HA prolongs the resorption time and remains within the practical timeframe for dental clinical applications; most of the graft material is converted into young bone within 3 to 6 months, and the remainder is resorbed shortly thereafter.

Recent studies [19,20] have demonstrated successful results in guided bone regeneration with the use of calcium sulfate, and in addition, based on histological analysis, the percentage of graft remaining was relatively low, with no evidence of inflammatory response or graft encapsulation.

In this preparation, there are several considerations of interest. In the first place, thanks to the Biphasic Calcium Sulfate formulation (hemihydrated/dihydrated), the setting process can be reduced from about 20 min to 3, facilitating clinical management. In addition, the synthetic hydroxyapatite particles decrease the rate of graft resorption, maintaining volume; the smaller ones (90 microns) are reabsorbed after 3–4 months and the larger ones (1 mm), which represent 10% of the total hydroxyapatite, are reabsorbed after 8 months. Finally, the high porosity of the product, greater than 46%, favors the infiltration of growth factors, osteoblasts, and angiogenesis [15,25,26].

Whereas with conventional graft materials there is integration with the graft particles resulting in 20%–25% vital bone formation, with Bond Apatite®, there is no integration between the newly formed bone, and the material is completely resorbed. Instead, new vital bone is formed at the end of the regeneration process.

Biphasic calcium sulfate serves as a cement, and its rigid structure after a quick setting prevents epithelial–conjunctive cell infiltration into the material, acting as a barrier membrane. However, connective cells can multiply on the material's surface, encouraging the rapid repair of the overlying soft tissue [24].

Bond Apatite® is presented as a powder in a double barrel syringe and a sodium chloride solution. With the help of a piston, the solution is poured over the powder, obtaining a mixture that can be easily deposited in the bone deficit, since the resulting product is adhesive. Subsequently, pressure must be exerted with a dry sterile gauze for a few seconds, thus eliminating excess liquid and favoring the setting of the product. In addition, the manufacturer recommends closing the flap under tension and it is not necessary to cover the graft with any type of membrane, since when it hardens it acts as a barrier preventing the penetration of epithelial–connective cells [25,26].

This study aims to review the existing literature on calcium sulfate in oral surgery and expose various clinical cases using Bond Apatite® as a bone graft material in different situations. Therefore, the following PICO (Patient, Intervention, Comparison, Outcome) question was: Does the use of calcium sulfate as a material in guided bone regeneration in dentistry have better results compared to other bone graft materials?


**Maria Jose Hernández-Serrano**

Department of Theory and History of Education, University of Salamanca, Salamanca, Spain

**1**

Section 1

Digital Evolution for Flexible

and Collaborative Learning

Environments


*4.2. Comparisons with the Existing Algorithms Based on the Shape of the Area of Interest*

Apart from the obstacle's densities, the shape of the area of intreat is also a relevant factor that can significantly impact the CPP algorithm performance. CPP over the regular shaped AOI is relatively easy compared to the irregular shaped AOI. The regular shaped AOI coverage can be obtained with the simple BF pattern. Meanwhile, the irregular shaped AOI coverage requires the concavities modification and hybrid motion patterns to achieve the full coverage. The CPP complexity varies with the shape of the target area and it requires obstacles' geometry knowledge to find the low cost solution for the coverage missions. To address this concern, we compared the proposed algorithm performance with the existing methods over five different types of the AOI to support generality. We performed rigorous experiments to verify the algorithm performance in relation with the shape of the AOI. The average computation time, path length and path overlapping are shown in Table 3.

**Table 3.** Proposed algorithm performance comparisons with varying shapes of the area of interest.

Through simulations and comparison with the two existing algorithms using five different shapes of the AOI, on average, our proposed algorithm reduces the computing time of pathfinding by 21.34%. From a path length point of view, it reduces path length by 8.98%. Additionally, the proposed algorithm has less path overlapping compared to the existing algorithms. We further compare our approach results of turning maneuvers with two existing methods in ten representative scenarios. Figure 9 shows the number of turns' comparisons between proposed and two existing algorithms. The proposed method shows 12.1% and 7.03% improvements in the number of turns as compared to BCDH-CPP and CA-CPP algorithm, respectively.

**Figure 9.** Turns comparisons: proposed algorithm versus BCDH-CPP and CA-CPP algorithms.

Apart from the numerical result, the proposed algorithm uses less number of sweeps compared to the decomposition based methods. Figure 10 shows the number of sweeps used by the proposed algorithm and decomposition based methods for the coverage of three cells (i.e., 5 to 7) of the AOI.

**Figure 10.** Footprints sweeps' comparisons with existing algorithms.

From the results, it can be observed that when the cell size is small and sufficient attention has not been paid to sensor/camera footprints size in area decomposition, the BCDH-CPP [53] and CA-CPP [54] algorithms (Figure 10b) need more sweeps compared to the proposed algorithm which can increase the path length in complex scenarios. In contrast, the proposed algorithm (Figure 10c) considers the sensor footprint as a coverage unit in the CPP and uses less sweeps to guarantee the perfect coverage.


*Article* **Read Like Me: An Intervention for Struggling Readers**

#### **Chase Young \*, Stacey Lagrone and Joyce McCauley**

School of Teaching and Learning, Sam Houston State University, Huntsville, TX 77304, USA<EMAIL_ADDRESS>(S.L<EMAIL_ADDRESS>(J.M.)

**\*** Correspondence<EMAIL_ADDRESS>
Received: 7 February 2020; Accepted: 21 February 2020; Published: 4 March 2020

**Abstract:** The current study reports on a reading intervention method titled Read Like Me. The intervention utilizes a stacked approach of research-based methods, including reading aloud, assisted reading, and repeated reading. The student involved was a second-grade boy reading below grade level who was identified as dyslexic and diagnosed with attention deficit hyperactive disorder. Using a single-case experimental design, the intervention was monitored in four phases, including a baseline, intervention coupled with regular schooling, intervention only, and a return to baseline. The results indicated that the intervention combined with regular schooling improved his reading expression and rate and also his decoding skills, word knowledge, and reading comprehension. In conclusion, the authors offer Read Like Me as one more intervention that may be a viable option for teachers in their effort to support developing readers.

**Keywords:** struggling readers; reading intervention; reading fluency; reading comprehension

#### **1. Read Like Me: An Intervention for Struggling Readers**

The theory of automaticity essentially purported that the more automatic readers become in word recognition, the more cognitive resources can be reallocated to higher-level reading processes, such as reading comprehension [1]. Stanovich [2] referred to the theory of automaticity as a critical precursor to many important reading theory developments. Decades later, it is still used to frame studies in reading, especially those that examine practiced-based methods [3–6]. The purpose of this study was to explore the effectiveness of a newly developed practice-based reading intervention for struggling elementary readers. The intervention, Read Like Me, is a multifaceted approach comprised of several researched interventions, including reading aloud, repeated readings, assisted reading, and the gradual release of responsibility. In light of the significant impact that the methods have on students' reading, the methods were combined to create a synergistic and potentially effective intervention.

Struggling readers need expert, research-based instruction [7] especially as the expectations grow for young readers. Students are increasingly required to read texts that are too difficult, a requirement that contradicts previous research [8,9]. Gradually, however, that perspective has changed [10], and students are frequently engaged in texts that are far more challenging. Allington [7] adamantly opposes this practice and reminds us that adults would likely refuse to read books at only 98%-word recognition accuracy, which would amount to approximately six unknown words per page. Regardless, here we are putting difficult texts into the hands of struggling readers.

Recently, Strong, Amendum, and Conradi Smith [11] described a similarly dim outlook on the current perspectives on text difficulty in modern reading education. However, the authors continued on to describe some of the research that may help educators consider the appropriate contexts for utilizing challenging texts. Before selecting a text, a teacher should consider the reader and also how much assistance will be provided. Thus, it might be possible for teachers to use difficult texts when administering interventions that provide sufficient supports for the reader.

Read Two Impress (R2I) [12] is an example of an intervention that calls for challenging texts, within approximately one year of the students' independent reading level. R2I is a hybrid of repeated readings [13] and the neurological impress method [14], both highly assistive methods for reading intervention. Read Two Impress has had large e ffects on students' reading fluency [15] reading comprehension [16] and independent reading level [17].

Young, Mohr, and Rasinski [15] claimed that the texts, however, were not frustrational, necessarily, but, rather, on the outer limits of the students' zone of proximal development [18] That is, adequate sca ffolds were applied, and the students were able to engage in successful reading. Furthermore, texts were modeled and then practiced, essentially following the tenets of the gradual release of responsibility [19]. Thus, in this case, the higher-level texts did not impede their reading growth but, rather, enhanced it. Similarly, researchers have found challenging texts optimal when engaging in close reading protocols [10]. Read Two Impress has had similar success with challenging text since its inception and first use with a third-grade boy named, Emilio (pseudonym).

Emilio started something back in 2009, though his story was not told until 2012 by Mohr, Dixon, and Young. He was a struggling third grader who did not respond to multiple reading interventions and intense guided reading instruction in the classroom. He was approaching a place where students rarely catch their peers in reading—the rich were getting richer, and Emilio was getting poorer [20].

The reading specialist then did some research and presented a few potential interventions to the students. Emilio chose repeated readings [13]. After several weeks, his reading rate and comprehension had improved, and his stagnant reading level shifted positively for the first time in a long while. However, he still read in a monotone voice and appeared to not enjoy reading, despite his progress. Because of his improvement, the reading specialist was hesitant to remove repeated readings as an intervention, and so, it was decided to add neurological impress [14] to improve his reading prosody. The methods were combined and appeared to have a synergistic e ffect on Emilio's reading. By the end of the ten-week intervention, Emilio was reading at grade level with adequate reading fluency and comprehension.

In addition, Emilio showed an interest in reading and claimed his favorite author was Je ff Kinney. This was important because he had no favorite authors or books at the beginning of the intervention [21]. It seemed that he was motivated by his progress, which is why the current study added an additional component to the R2I protocol, reading aloud. While R2I has been used successfully with struggling readers, it seemed there were two missing pieces, including a complete modeling of the text and an opportunity for the student to read the text aloud as a whole.

The genesis of Read Like Me resulted from the promising results of R2I, and while the method improved reading fluency and comprehension, it failed to improve students' attitude [16]. It was decided that the method, while powerful, lacked authenticity. Students were not given the opportunity to read the text as a whole and feel the success of reading a challenging text from beginning to end. Therefore, the researchers added a few other elements, a concept often used with struggling readers typically referred to as "stacked instruction". This approach takes multiple research-based interventions and stacks them to work in a more synergistic and powerful way [21].

Thus, the researchers framed Read Like Me based on a whole-part-whole instructional process in the hopes of adding authenticity while simultaneously stacking instruction. In Read Like Me, the tutor reads the entire text aloud and entertains the student with a prosodic read aloud, then the tutor and student use R2I to assist the student in developing mastery of the text, and finally, the student reads the entire text aloud—in the end, the student engages in successful authentic reading.

#### **2. The Benefits of Reading Aloud**

Reading aloud is one way to model how words printed on a page are converted into oral language with all of the variables of timing, phrasing, intonation, and emphasis (prosody) that speakers use. More simply, reading aloud models how the written word becomes the spoken word. The e ffects of good read alouds on literacy learning have been supported in the literature for many years [22–25]. These include fostering vocabulary growth [26,27], developing listening comprehension [28,29] and expanding an understanding of good sentence and story structure [30,31].

Beyond the cognitive benefits of read alouds (and perhaps more importantly) is the impact on a ffective factors. Choosing to read is determined by attitude and desire [32,33]. Reading aloud positively influences the attitudes of children toward reading and motivates them to want to read [23,34]. Hearing a story read in its entirety, being swept away by the words and the images they create, and experiencing the power of language to cause one to laugh or cry or wonder or hold your breath—all encourage youngsters to want more and, eventually, to be able to read it themselves. Having good models that bring text alive through the natural rhythm and beauty of language, encourages children to want to read just like that.

In Read Like Me, the interventionist begins the session with a powerful read aloud, allowing the child to hear the text in its entirety. Modeling the way language works to create vivid pictures of story, pulls the child into the text right from the start. As the text is revisited in smaller sections (using the impress method), the child is encouraged to use the same timing, phrasing, intonation, and emphasis. At the conclusion of the session, the child reads the whole book back.

As we know from years of research, perception of self as a reader, an a ffective factor, is an important determinate in reading success [35–37]. Using this intervention, Read Like Me, encourages children to see (and hear) themselves as good readers.

#### **3. Significance of the Study**

Early literacy was considered a hot topic and deemed the most important in the 2018 What's Hot What's Not survey [38]. Reading research has been conducted for centuries, but yet, there is still a need for additional reading interventions, as no one intervention will work for every student. Thus, teachers need access to a plethora of options to support young readers who find the process di fficult. This research aimed to describe a newly developed option for reading intervention and to track the growth of a second-grade student who has di fficulty reading for a variety of reasons. The research was guided by the following research question: What are the e ffects of Read Like Me as a supplemental and a standalone intervention for a second-grade student who struggles with reading?