## 4 Discussion  
This cohort study conducted during the Master of Medicine, Surgery, and Oral Implantology course at the University of Barcelona on 192 patients treated with Bion horizons(r) dental implants concluded a 2.13% failure rate, in line with the percentages found in the literature [28; 29], with a 97.87% survival rate across a range of 6 months to 3 years, a figure within the values established by most previous works. However, other investigations exposed higher failure rates in postgraduate students, between 3.9% and 16% [27; 29]. The results found statistically significant values for implants that failed early (\(p<0.0001\)), coinciding with some authors, who stated that the early failure rate is greater than the late failure rate [30; 31]. This type of failure is attributed to the first phase of treatment, which covers variables such as patient condition, surgeon experience, the type of surgery, and post-operative care. The main causes include periodontal disease, smoking habit, surgical complications, surgeries at the same time as bone regeneration, a lack of primary stability, infections, high healing abutments, and immediate loads on occlusion [32; 33]. However, these variables were not significant in our study; this may be due to the percentage of the sample that presented the evaluated risk factors, unlike research with larger sample sizes. Implant failures relating to location on the arch did present statistically significant differences between the anterior/posterior sector and association with early failure, \(p=0.027\) and \(p=0.014\), respectively. There is no concordance between the prevalence of failure of implants based on location. There are studies to support the theory that the superior maxilla, on being a more porous bone and easier to reabsorb, presents more implant losses than the mandible [34; 35]. As opposed to other investigators who explained that a higher failure rate occurs in the mandible region over the short-term, this is down to the cortical thickness and limited mandible vascularization [9]. Among the factors studied in this study, no statistically significant differences were presented regarding patient gender. The average age (54.5 \(\pm\) 13 years old) is similar to the age in other retrospective studies conducted in universities with an average age of 54.4 years old [3; 29; 36], given that it corresponds to the patterns of incidence and prevalence when more tooth loss starts to occur [37]. As was already stated, the patient's systemic condition and habits play a key role in the survival of implants over the short- and long-term. No significant differences were found between bruxism and implant failure. Although this study showed that patients with a history of periodontal disease did not present a higher level of implant failure compared to patients without a history of periodontal disease, studies with a larger sample size have suggested that periodontal disease is a risk factor for implant failure [21; 22]. Our study did not find any statistically significant differences between patients that smoked <10/>10 cigarettes a day with implant failure and survival. However, investigation over time indicates a high risk of failure among patients with a frequency of over 15 cigarettes a day [3; 38]. Currently, studies have shown that patients allergic to penicillin present higher early implant failure due to a lack of osseointegration and infection due to the effects of clindamycin on bone cells [39; 40]. Although the results regarding patients allergic to penicillin were significant in our study, they should be treated with caution as the same patient presented allergy to all the studied drugs. As was already mentioned, bone regeneration is classified as a risk factor [12; 14]. The survival rate at 5 and 10 years for implants placed in regenerated regions drops from 90% to 79% compared to implants placed in native bone [41].