INTRODUCTION

Bone regeneration in the human body has been studied over the past century with a wide variety of purposes, approaches and surgical materials¹. Bone grafts are indicated in medical and dental practice for restoring compromised function and aesthetics due to bone defects². In oral surgery, bone grafts contribute to the treatment of small to moderate bone defects resulting from periodontal or endodontic disease, dental socket filling after extraction, maxillary sinus lifting or rehabilitation of bone atrophy prior to implants, and even large bone defects caused by traumas, congenital deformities, pathologies and infections involving the maxillofacial complex³.

The choice of a bone substitute should be guided by its physicochemical, mechanical and biological characteristics, including architecture, porosity, resistance, biocompatibility, biodegradability, osteoconduction, osteoinduction and/or osteogenesis, in order to mimic the bone tissue to be repaired⁴. Biomaterials can be classified according to their origin (autogenous, allogeneic, xenogeneic or alloplastic), composition (metals and alloys, ceramics and bio-glass, polymers or composites) or interaction with the biological environment (bioinert, bioabsorbable or bioactive)⁵.

There are advantages and limitations in the use of bone grafts. Higher success rates have been achieved with autogenous bone, despite its limited supply and higher morbidity^5,6. Donated allografts are more readily available, having been reported over the last sixty years and used increasingly Europe. However, difficulties in processing the biomaterial and risk of an immunogenic inflammatory response may reflect delay or decrease in osteogenesis⁶. Xenografts have been popular since the 1960s, especially bovine bone, despite the controversies with relation to the risk of transmission of xenozoonoses, which, in fact, have never been documented in dental practice⁷. Currently, animal byproducts could subsidize the generation of natural materials and contribute to the consolidation of a sustainable industry⁸. Alloplastic materials are satisfactory alternatives to natural materials, but face the challenge of controlling the great variability of results depending on their composition, associated with resorption and inflammatory or repair responses⁹. In view of this evidence, there is still no ultimate or single biomaterial for bone reconstruction, which motivates the biotechnological development of the sector¹⁰.

The growth of the industry and the consumer market for bone substitute materials for dental use converges with the higher life expectancy of the population and the increase in purchasing power in developing countries¹¹. This market is markedly significant in North America, followed by Europe, Asia, Latin America, Oceania and Africa¹². A worldwide increase of 4.4%¹³ to 9.5%¹² is estimated for the period from 2018 to 2026 in guided bone regeneration procedures involving bone grafts and membranes, which may be associated with greater clinical demand from both professionals and patients seeking better results¹³. In the United States and Europe, more than half a million people annually receive treatment for bone defect repair, and the international bone graft market moved USD 493 million in 2018 and expects to generate USD 931 million by 2025¹⁴. In Latin America, this market was valued at USD 116.8 million in 2018¹⁵. In Brazil, the political and economic crisis in the country and the bureaucracy involved in opening new companies are expected to delay the growth of this sector¹³. In a price-sensitive market, the costs and benefits of bone graft procedures should be considered for clinical choice¹⁶.

In this broad market scenario, there is a lack of evidence in the literature about the permeability to bone grafts in dental practice in medium and small cities. The city of Sobral, located in the interior of the State of Ceara, northeastern Brazil (3°41'42.0"S 40°20'28.3"W) is located 232 km from the state capital, Fortaleza. It has an estimated population of 208,935, being the fifth-largest city in this Brazilian state, with a rate of 24.6% of professional occupation, average of 2 minimum monthly wages, gross domestic product per capita of R$ 20,258.09 or USD 4,771.08, municipal human development index of 0.714, 88.35% of urban population, 67.83% in the 15- to 64-year age group and Gini index 0.56¹⁷. There are 39 outpatient units with dental care, 1 emergency facility with maxillofacial surgery¹⁷, 44 oral health teams in primary care, 2 dental specialty centers (1 municipal and 1 regional) in secondary care¹⁸ and 2 schools of dentistry (1 public and 1 privative) with dental care for the population. In the Sobral Campus of the Federal University of Ceara, it was estimated that in 2019, about 4,000 procedures involving oral surgery, periodontics or implantology were performed at the dental clinic.

Thus, the aim of this study was to assess the general profile of use of bone grafts in the perception of dentists in the Brazilian inland.

MATERIALS AND METHODS

RESULTS

Among the 233 dentists in the city of Sobral, a total 183 volunteers comprised the sample, equivalent to 78.54% of the city's professionals. Remarkably, the sample used in this study was greater than the size determined using statistical parameters as mentioned above. The representative sample of dentists in this study increases the level of confidence in the results found for the city of Sobral.

The prevalence of females (117 participants) was almost double that of males (66 participants) (Fig. 1A). Mean age±standard deviation was 35.37±10.21 years and there was prevalence of three quarters of the sample in the age group up to 40 years (Fig. 1B). The vast majority of the sample did not have any specialization or expertise in Orthodontics (Fig. 1C). Table 1 shows respondents' general knowledge about bone grafts. Most respondents sample had graduated up to 10 years previously and demonstrated significant familiarity with the subject. They had acquired such knowledge mainly at undergraduate level, in comparison to postgraduate studies and dental conferences. Among the natural or synthetic compositions mentioned, ceramics were the most prevalent, followed by composites, while there was little mention of polymers and glasses. Bovine mineral bone was the material most frequently cited by all participants.

Fig. 1 Profile of dentists in the city of Sobral, Brazil (n=183). 

Table 1 Knowledge about the subject of bone grafts among dentists in Sobral, Brazil (n=183). 

Table 2) shows that only a quarter of the respondents (45 or 24.59%) had performed bone grafts. Regardless of the intensity of use (from <10 to >100 cases), the most frequent bone graft applications were simultaneously with a dental implant, fresh dental sockets and maxillary sinus lifting, while the least frequent were periodontal use, paraendodontic use and extensive bone reconstruction. Autogenous and xenogeneic grafts were more often used than alloplastic and allogeneic grafts. Ceramics were the most frequently used composition of bone grafts and their association with membrane was more frequent than bone graft alone or associated with autologous fibrin.

Table 2 Specific use of bone grafts by dentists in Sobral, Brazil (n=45). 

Table 3) shows the high satisfaction of professionals and patients with bone grafts, with material or technical costs being considered moderate.

Table 3 Cost-effectiveness of bone grafts for dentists in Sobral, Brazil (n=45). 

However, the fact that professionals never or rarely include the patient in the choice of this form of treatment is remarkable. The reported country of origin of the bone graft used differed significantly according to how many bone grafts the respondent had performed: most of those who had performed up to 10 cases did not know country of origin or had used imported material, while respondents who had performed over 50 cases reported using imported or imported+national materials. Use of bone grafts was higher in the private service than in the public for most of the analyzed ranges.

Table 4) shows that professionals always follow datasheets and recommendations for the use of bone grafts. Respondents who had performed up to 50 cases did not overall report having patients with inflammatory or infectious complications after bone grafts, while the profile is significantly reversed for respondents who had performed more than 50 cases, although they reported feeling safe regarding the origin of the materials. In general, both the opinion of the professionals and their perception of the belief of their patients were more favorable to the use of bone grafts from animals than from humans. Within all three dental specialties, the low number of professionals registered in the Brazilian Transplant System for use of bone tissue banks confirms the low level of acceptance among professionals of allografts, with only 2 registered dentists in the specialties of Oral and Maxillofacial surgery or Implantodontics.

Table 4 Biosafety of bone grafts for dentists in Sobral, Brazil (n=45). 

DISCUSSION

The local register of 233 dentists for a population of 208,935 inhabitants in Sobral¹⁷ shows the ratio of 1 professional to 896 individuals, which is a lower rate than the Brazilian average of 1 dental professional to 668 inhabitants²⁰. Even in the face of favorable demand, the low number of experts would explain the generalist profile of dentists in the city and may explain the low use of bone grafts in the sample. Inorganic bioceramics were bone substitute materials most frequently cited and used by respondents, in agreement with most studies on the subject^9,21,22. This preference is supported by osteoconductive action, ability to carry osteogenic cells^9,21 or osteoinductive growth factors²³, versatility of concentrations, formats and particle sizes²² as well as the possible association of apatites with collagen or other polymers with the aim of achieving biological synergism^15,21,24. Thus, the basic understanding of the properties of biomaterials for bone regeneration and their appropriate applications is very important in making a good clinical choice¹⁹.

The most frequent clinical applications were simultaneous use with a dental implant, fresh dental sockets and maxillary sinus lifting, in agreement with the two most prevalent surgical beds in the dental literature^19,24,25. The present study found a higher frequency of bone graft in association with membranes or autologous fibrin than in isolated form, disagreeing with another Brazilian study¹⁹ and international reports, which state that dentists make less use of membranes next to the bone graft because it represents an additional cost to the patient^16,26. The adjunct use of autologous fibrin has been promising, as it has a high concentration of angiogenic and osteogenic growth factors, evidencing the evolution of bone regeneration techniques²⁷.

The prevalence of use of autogenous and xenogeneic grafts compared to alloplastic and allogeneic, associated with a more favorable perception of the use of bone grafts from animals than from humans, agrees with other studies on the topic^19,28. Autografts are a gold standard for the treatment ofbone defects²⁸, but the preference of professionals for xenografts and alloplastic grafts has increased gradually in Latin America¹⁵ and Brazil²⁶ for medical and dental applications^3,22. The advantages of xenografts and alloplastic grafts are biomimicry of human bone tissue²⁴ and absence of patient's donor bed, which explains their wide range of clinical uses^9,19,22. Stigmatization of the cadaverous source, lack of disclosure²⁹ and ethical, moral or religious values of users could explain low choice of allografts^30,31. Satisfaction with bone grafts in this study was high, confirming an Indian study with 59% of utilization³¹. Refusal rates to bone grafts has been more often associated to the geopopulational context than to age, gender, education and religion, ranging from 2% for alloplastic grafts to 20% for allografts in Chilean study³⁰ or from 11% for autografts to 67% for xenografts in Saudi Arabia²⁹.

The present study confirmed the existing knowledge on use ofmaterials ofimported^12,13 or national origin²⁴. Multinational companies, predominantly US, currently dominate the global market for dental bone grafts^12,13. Brazilian industry gains representation among companies already consolidated in the market, with 3 out of 5 institutions responsible for 65% of dental bone grafts in the country²⁶.

Costs were considered moderate by the respondents, predominantly from private practice in Sobral, a finding similar to those from a large city in southeastern Brazil¹⁹. However, the country suffers from chronic underfunding in public health³², where the costs of procedures can be substantial limitations^13,33 and only a small percentage of its population has undergone bone reconstruction procedures^16,34. In private practice, costs are associated to the loyalty of dentists to the use of bone grafts³³.

Dentists may select therapeutic options that involve high cost, based on their perception of the patient's profile and oral condition or on the patient's feedback regarding motivation or being able to afford the cost of the treatment³⁵. The current study highlighted the low level of patient participation in the choice of material to be grafted, in contrast to most international studies^29-31,35. This emphasizes the need to improve professional interaction with patients in order to make successful joint decisions regarding the use of bone graft.

High occurrence of inflammation or infection in grafted patients was proportional to high density of surgical care performed by the respondents. The rigid biosafety involved in processing, sterility and standardized validation tests of grafting^12,36 reduces fears regarding the transmission of animal or human diseases^30,31 and increases the safety perceived by dentists regarding their use³⁷. Nevertheless, grafting procedure failure can range from 5 to 10% as a result of infections or inappropriate graft stabilization¹⁵. Factors such as filling large bone defects with bone block, mixed grafts (autogenous + synthetic) and diabetes mellitus may also be associated with infections³⁸. To reduce potential out-of-office complications with bone grafting, it can be helpful to apply antibiotic therapy used sparingly³⁹ and intensification of care with oral hygiene habits³⁴. Although there is still little dental use of bone grafts in Sobral, their cost-effectiveness and biosafety are generally satisfactory and in accordance with the literature. This study confirms good acceptance by dentists and their knowledge of the subject of bone grafts in Sobral, a medium-sized city in the Brazilian inland, which constitutes a promising scenario for the development of the sector.