The effects of sodium alendronate on socket healing after tooth extraction: a systematic review of animal studies

Abstract The aim of this systematic review was to answer the following question: “Does alendronate, a nitrogen-containing bisphosphonate, improve or impair alveolar socket healing after tooth extraction in animal models”? To this end, a systematic review of the literature was carried out in PubMed, Scopus, LILACS, Web of Science, as well as in the gray literature up to May 2023. Preclinical studies that evaluated alveolar healing after tooth extraction and the intake of sodium alendronate compared with placebo were included. Two investigators were responsible for screening the articles independently, extracting the data, and assessing their quality through the SYRCLE’s RoB tool for randomized trials in animal studies. The study selection process, study characteristics, risk of bias in studies, impact of alendronate on bone healing, and certainty of evidence were described in text and table formats. Methodological differences among the studies were restricted to the synthesis methods. The synthesis of qualitative results followed the Synthesis Without Meta-analysis (SWiM) reporting guideline. From the 19 included studies, five were considered to have low risk, three were of unclear risk, and eleven presented a high risk of bias. The studies were considered heterogeneous regarding alendronate posology, including its dosage and route of administration. Furthermore, a variety of animal species, different age ranges, diverse teeth extracted, and exposure or not to ovariectomy contributed to the lack of parity of the selected studies. Our results indicated that alendronate monotherapy negatively affects the early phase of wound healing after tooth extraction in preclinical studies, suggesting that the bone resorption process after tooth extraction in animals treated with alendronate might impair the bone healing process of the extraction socket. In conclusion, alendronate administration restrains bone resorption, thereby delaying alveolar socket healing . Future studies should be conducted to validate these findings and to better understand the effects of alendronate therapy on oral tissues.


Introduction
Alendronate has become the drug of choice for osteoporosis treatment because of its recognized anti-remodeling effect in most human skeletal Declaration of Interests: The authors certify that they have no commercial or associative interest that represents a conflict of interest in connection with the manuscript.
regions, including the hips, spine, femoral neck, tibia, and wrist. 1 All bisphosphonates (BPs) aim to reduce bone resorption, to improve bone mineral density, and to decrease the risk of fractures. 2The main therapeutic target of BPs is the osteoclast, whose inactivation inhibits osteoclastogenesis and prevents osteolysis. 3Among oral BPs, alendronate is the most efficient in slowing down skeletal remodeling and turnover.On the other hand, some serious side effects can occur in long-term BP treatment. 4][12][13][14][15] ONJ is the main adverse effect of orally administered BPs. 12,14ONJ cases associated with BP therapy have been increasingly reported in dental clinics since 2003. 16The incidence of ONJ related to alendronate ranged from 0.01 to 4%. 17 These pathological cases involve very high morbidity and treatment challenges, thus demanding a major effort in their prevention.It is still not fully understood how suppression of bone remodeling can affect the intrinsic properties of bone metabolism (mineralization, turnover rates, collagen crosslinks, microdamage, etc).Although ONJ has been documented to occur spontaneously, 12 it is most commonly associated with trauma induced by a dental procedure, such as tooth extraction and periodontal/periapical disease. 14,15 18 19Research studies have focused on elucidating the role of tooth extraction in triggering the onset of ONJ in patients treated with alendronate for long periods of time. 20o date, one cannot predict who is prone to develop ONJ, which represents a dilemma for clinicians dealing with risk assessment.Currently, there are no reliable biochemical markers to guide preventive strategies for ONJ.This condition is characterized by the presence of a non-healing exposed bone in the maxilla or in the mandible, persisting for more than 8 weeks in a patient who has received systemic BP treatment but has not received head and neck radiation therapy. 21,22Persistent jaw bone pain, bone enlargement, gingival swelling, jaw bone fractures, pus, and unpleasent mouth odor, are some clinical symptoms described in ONJ. 23][26] However, the following questions still need to be properly aswered: Can the antiresorptive effect of alendronate on the alveolar bone prevent crestal bone loss after a tooth extraction?Can we expect to find dead bone in this area?Does alendronate enhance bone fill in socket healing?What is the consequence of decreasing bone remodeling in a dynamic metabolic enviromnent?To deal with these questions, it is important to know the specific characteristics of the jaw bones: The cortical bone of the alveolar region has a high turnover rate of ~25% per year, compared to 1%-2% per year in the tibial or femoral diaphysis. 27A very thin mucosal layer covers the bones, which can break easily, leading to exposure in a bacteria-laden environment and a heightened risk of infection.While some authors consider alendronate the therapeutic solution to enhance bone healing and to prevent alveolar bone loss, 24,28 other studies posit that alendronate delays the socket healing processes and leads to non-vital bone accumulation. 6,29 dditionaly, the final mineralization process and the type of collagen cross-linking in newly formed bones are still not completely understood in the presence of BPs. 30,31  ud ie s u si ng a n i m a l model s to m i m ic experimental conditions are widely used in various human-related diseases.The use of experimental tooth extraction and ONJ models permits the study of the molecular mechanisms involved in the immunopathogenesis of diseases and in the healing process that occur after tooth extraction.The tooth extraction model in rabbits and rodents assist in the understanding of events that lead to bone resorption and remodeling resulting from dental extraction.The healing process after tooth extraction in animal models mimic the events that occur in humans and, consequently, are well indicated for the study of bone and soft tissue healing progression.These animal models also contribute to the development of new treatment strategies and supporting decisions about human clinical research.Systematic reviews of preclinical

Eligibility criteria
The controlled vocabulary (MeSH terms) and free keywords in the search strategy (Table 1) were defined based on the elements of the PICOS question: a).Population (P): Experimental laboratory animals (rat, mouse Only experimental animal trials that conducted tooth extraction under the effect of alendronate, in comparison to a placebo, were eligible.No miminum follow-up period was required.Despite the fact that the tested drug aimed to treat osteoporosis, ovariectomy or any other model to simulate postmenopausal phase-induced bone loss was not considered an inclusion criteria, neither was the sex of the animals.The primary outcome of this systematic review was the histopathologic results regarding the expression of alveolar socket healing in terms of quantity and/ or quality of soft tissues and bone.In addition, microcomputed tomography was also included.No restrictions on animal species or breed were established.The exclusion criteria were as follows: non-controlled experimental animal trials, editorial letters, pilot studies, historical reviews, and in vitro studies were excluded.Moreover, studies were excluded if the post-extraction alveolar socket was filled with any bone substitute material.Studies that utilized alendronate in combination with other drug and did not have a group of non-mixed drugs were also excluded.Dosage and route of administration were not considered exclusion criteria.

Information sources and search
Two authors (N.G.M.C. and R.S.M.), guided by a specialized librarian (D.M.T.P.), independently conducted an electronic search up to October 2023 (subsequently updated by alerts) in the PubMed/ MEDLINE, Scopus, Web of Science, Latin American and Caribbean Health Sciences Literature database (LILACS), Brazilian Library in Dentistry (BBO), and Cochrane Library (Table 1) to compile the reports for this systematic review.Additional publications were retrieved by manual search of the reference lists from primary studies.There were no restrictions on publication data and languages.The grey literature was utilized to identify eligible studies in the opengrey (opengrey.eu-Grey literature database) and Theses database.Table 1 presents the search strategies, which were appropriately modified for each database.

Selection process
The retrieved articles were exported to the Rayyan Reference Manager (https://www.rayyan.ai)and duplicates were removed by the program (perfect match) and manually.The selection process was conducted in two phases: In Phase 1, two researchers (N.G.M.C. and R.S.M.) independently examined the titles and abstracts of all retrieved references, applying the inclusion criteria; and in Phase 2, the same two reviewers independently applied the exclusion criteria during the full-text screening.The full texts were evaluated and judged in the entire document.Interrater reliability in the study selection process was determined by Cohen's kappa, assuming an acceptable threshold value of 0.80. 34The disagreement at any stage was resolved by discussion and mutual decision with a third reviewer (LCM).

Data collection process
Each included article was numbered and catalogued under the name of the first author and year of publication.A customized data extraction form was made to record all information necessary to validate the article in agreement with the eligibility criteria and with the research question.The following topics were used for data extraction: a) details of the study, including year of publication and authors; b) details of the participants, including type, age, and weight of the animals; c) details of the study methods, including study design, experimental groups, ovariectomy, tooth extracted, sample size, and follow-up period; d) details of drug posology, including allometric tests and clinical drug relevance; e) details of socket healing after tooth extraction, including timing of alendronate intervention and healing period; f) details of the outcomes, including histopathologic elements (osteoclast, osteoblast, alveolar bone fill, non-vital bone accumulation, bone remodeling, epithelial coverage, inflammation, blood vessels, collagen apposition, and osteonecrosis) and microcomputed tomography.

Risk of bias in individual studies
The SYRCLE's risk of bias tool for animal studies was employed to assess the methodological quality of the selected studies. 35Ten entries related to six domains of bias comprised this adapted version of the Cochrane RoB tool: selection bias, performance bias, detection bias, attrition bias, reporting bias, and During data extraction and risk of bias assessment, any disagreement between the reviewers was resolved through discussion, and whenever necessary, by consulting a third reviewer (LCM).The judgment of each entry involved recording 'yes' for low risk of bias, 'no' for high risk of bias, or 'unclear' for either lack of information or uncertainty about the potential for bias, as described in the SYRCLE's risk of bias tool.Studies were considered to have a 'low' risk of bias if there was adequate sequence generation and allocation concealment (key domains).When the study was judged as 'unclear' in its key domains, we tried to contact the authors to obtain more information and to allow a definitive judgment about 'yes' or 'no'.

Synthesis methods and effect measures
The study selection process, study characteristics, risk of bias in studies, impact of alendronate on bone healing, and certainty of evidence were described in text and table formats.Methodological differences among the studies were restricted to the synthesis methods.The synthesis of qualitative results followed the Synthesis Without Meta-analysis (SWiM) reporting guideline. 36

Risk of bias within studies
50,51 Twelve studies reported the randomization process for group allocation, but the sequence generation and the allocation concealment were not described in any of them. 11,37,39,40,42,44,45,47-49,52- 53In five 39,42,45,[52][53] studies, the authors described the characteristics of the animals in sufficient detail to consider the experimental groups to be similar at baseline and to judge the study as having "low"' risk of bias.0,51 The authors did not provide information about the random placement of cages or animals within the animal room/facility.So, all of them received an unclear score in this domain.Only two studies 37,42 reported that the investigator was blinded to the treatment allocation, and five studies stated that the outcome evaluator was blinded. 11,37,39,41,47The incomplete outcome data were adequately addressed in only three studies. 10,39,50All reports were unclear about selective outcome reporting, and four studies 39,43,45,49 were apparently free of other problems that could result in high risk of bias.

Characteristics of included articles and synthesis of the ressults
The characteristics of the 19 selected studies 10,11,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] are listed in Tables 3A and 3B.A total of 798 animals had been included in all eligible articles, distributed as 157 Spraguey-Dawley rats, 259 Wistar rats, 176 Holtzmann rats, 141 C57BL/6 mice, 12 mongrel dogs, 15 beagle dogs, and 38 New Zealand rabbits.The rat was the animal chosen in 15 out of 17 reports.In 12 studies, 10,11,37,38,[42][43][44]46,[49][50][51]53 the age of the animals at baseline ranged from 4 to 10 weeks, and in five studies, 39,40,45,47,48 at the end of the experiments, the animals were 12 weeks old or older. Two studiesdid not provide the age of the animals 41,52 and four studies 10,44,49,50 did not give the mean weight of the animals.The maxillary molars were extracted in eight reports, 37,39,43,44,46,47,49,51 the mandibular molars were extracted in eight reports, 10,11,38,41,42,45,48,50 and the mandibular and maxillary premolars were extracted in one study.40 Ovariectomy was performed in three studies.40,44,51 The clinically equivalent dose of the alendronate used in the animal studies were assessed by an allometric test, using a metabolic dose. 54 There was agreat variability in the doses given to the animals, when compared to human doses.One study 47 prescribed a dose 333-fold under the clinically equivalent dose, while another study 51 prescribed a dose 253-fold above it.Only four studies 39,40,45,52 were comparable to the 70 mg/ week oral dose in postmenopausal women, and nine studies 11,37,38,42,44,46,50,51,53 exceeded the principle of the tenfold safety factor, proposed by Freed (2006).55 The subcutaneous route of administration was used in 12 studies, 10,11,[37][38][39]41,43,44,46,[49][50][51] oral gavage was used in six studies, 40,42,45,47,52,53 and one study used local administration.48 The duration of alendronate therapy *Consider, if feasible to do so, reporting the number of records identified from each database or register searched (rather than the total number across all databases/registers). **If automation tools were used, indicate how many records were excluded by a human and how many were excluded by automation tools.ranged from 5 days 43 to one year 45 and the socket healing period ranged from 3 11,43,46,49 to 105 days.47 Histologic analyses were perfomed in all studies, except in two 40,44 (Tables 4A and 4B).In 11 out of 12 studies that measured bone fill, alendronate was associated with an early-stage delay in the healing process.10,11,38,[41][42][43]48,[50][51][52][53] For instance, a study conducted by Aguirre et al. 10 showed that moderate dosage of alendronate decreased 55% of woven bone volume compared to the control group, and reduced 75% of woven bone volume at high dosages.Alendronate also reduced the eroded surface of the interalveolar septum by 90%. Another study perormed by Conte Neto et al. 11 showed that animals treated with alendronate retained the interradicular septum, which was associated with bone necrosis and infection.Altundal et al. 38 showed that alendronate decreased bone fill and resulted in thicker buccal and lingual alveolar bone in the alveolar socket.Yamamoto-Silva et al. 50 stated that alendronate decreases bone formatio at day 7 (0%), 14 (≈ 10%), and 21 (≈ 20%). A small mount of new bone formation was observed compared to the control group at days 7 (≈ 40%), 14 (≈ 60%), and 21 (≈ 60%).On the other hand, Aguirre et al. 10 demonstrated that moderate and high doses of alendronate increased cancellous and cortical bone mass (35.94 ± 10.71 and 36.01 ± 10.08) compared to the control group (19.61  ± 4.32), presumably due to their inhibitory effect on bone resorption.Yamazaki et al. 51 showed that alendronate-treated rats exhibited a small amount of new immature bone in the extraction socket (≈25%) compared to the control group (≈ 50%) at day 7.After 14 days, newly formed bone in the socket had an irregular mesh and granulation tissue. Th newly formed bone (≈ 60%) lacks the bone-like fiber bundle compared to control animals (≈ 80%).Finally, at day 28, alendronate decreased bone formation (≈ 70%) compared to the control (≈ 100%).
2][53] For instance, the study made by Aguirre et al. 10 showed that in three out of nine alendronate-treated rats (33%), the interdental alveolar bone exceeded the superficial surface of the socket, which was occupied by inflammatory tissue and not covered by oral epithelium.In these cases, the interdental bone appeared to protrude into the oral cavity.These data were corroborated by a study made by Maahs et al., 47 which demonstrated that alendronate increased the loss of mucosal integrity by 72.7%.Previous studies have also shown that alendronate treatment impaired epithelial coverage with concomitant exposed bone to the oral environment. 11,41,42,45 Insix out of 10 studies, alendronate therapy postponed inflammation resolution 11,45,[50][51][52][53] by increasing the number of neutrophils and the inflammatory infiltrate. 11,45,49,500][51][52][53] For example, Altundal et al. 38 showed that the number of osteoclasts in animals treated with alendronate decreased compared to control animals, which is in agreement with a study c by Hikita et al. 43 Yamamoto-Silva et al. 50nd Yamazaki et al. 51 showed that alendronate therapy induces atypical osteoclast morphology and non-functional osteoclasts characterized by the lack of ruffled border and large distance from the bone surface.Recently, Isaias et al. 52 have also demonstrated that alendronate therapy induced osteoclast formation with signs of intracytoplasmic vacuolization at the doses of 5.0 and 7.5 mg/kg.
Regarding empty osteocytic lacunae and bone sequestra, Aguirre et al. 10 showed that animals treated with alendronate displayed a 2.5-fold increase in the percentage of empty osteocytic lacunae.Kim et al. 46 also showed that alendronate significantly increased empty osteocytic lacunae (74.33 ± 10.50) compared to the control (41.67 ± 15.50), which was corroborated by other studies. 41,42 45 49,50n four out of six studies, alendronate hindered angiogenesis 11,38,41,50 and inhibited lymph angiogenesis in one study. 49In three out of four studies, it reduced collagen apposition rates, [49][50][51] and in four out of five studies, it diminished the number or functions of osteoblasts. 10,38,50,51Socket healing was also investigated by microcomputed tomography in six studies. 40,42,43,46,51,53Three of them showed lower bone density in the alveolar socket at 7 46,51 and 30 days 51 of healing in the alendronate group.Hikita et al. 43 showed that the proportion of newly formed bone (BV/TV) increased in the alendronate group, ranging from 16.90 ± 8.66 at 3 days after tooth extraction to 74.99 ± 4.02 after 14 days.
No meta-analysis was conducted, due to the lack of homogeneous results for the construction of summary measures.

Discussion
The results of this systematic review indicate that alendronate monotherapy negatively affects the early phase of wound healing after tooth extraction in preclinical studies.Our findings suggest that alendronate administration restrains bone resorption, delaying the alveolar socket healing process .
The retrieved studies in this review used rats as the most frequent animal model to study socket healing after tooth extraction under alendronate administration.The advantages associated with this animal model include rapid bone turnover, convenient size, ease of housing house and care and, particularly, low purchasing and maitenance costs. 56On the other hand, some authors cited a few constraints related to the rat model for socket healing, such as limited alveolar bone content, high prevalence of root fractures during tooth extractions, dissimilar bone morphology compared to larger mammals with the absence of Haversian systems, and low rate of cortical bone remodeling.Furthermore, rats do not reach a true skeletal maturity due to their continuos growth throughout their lifespan. 57o better assess the therapeutic effects of antiosteoporotic drugs, the animal model should display a postmenopausal bone loss similar to that of humans.Bilateral ovariectomy is the most common techique for estrogen depletion, leading to bone loss and providing a useful model for the prevention and treatment of osteoporosis.Some authors feed the animals a low calcium and phosporous diet to optimize ovariectomy, 40,58,59 while others combine glucocorticoid therapy with ovariectomy and alendronate. 60Unfortunately, ovariectomy was performed in only three reports 40,44,51 and, accordingly, 16 out of 19 reports were not able to answer whether alendronate can reverse low bone density or prevent bone loss, presenting an osteoporosis-induced challenge.
Rats under 3 months of age do not reach the peak bone mass, so the assessement of bone loss can be misleading in such young animals.Considering the rapid growth of these animals, the lower bone mass could be due to impaired bone growth rather than to accelerated bone loss, as observed after menopause. 57In the 3-month-old mature rat model, bone growth slows down considerably, which allows for the simulation of menopausal experience.In this review, only three studies employed animals older than 3 months, which is considered an appropriate model for postmenopausal bone loss. 39,45,47nother important concern when exploring the effects of pharmaceutical drugs in animal models is the clinically equivalent dose.BPs are effective inhibitors of bone resorption, depending on the dosage. 2This reveals the researchers' general tendency to increase doses in experimental trials in order to obtain positive results, increasing the clinically equivalent dose and, consequently, drug toxicity.To avoid misleading results, investigators should normalize the medication through an allometric method. 54The metabolic dose is considered the best method to achieve a more reliable equivalent dose, but there is no universally accepted means to do that.To compare effective doses, Marie 61 states that we should use drug concentration in the circulating serum.In this review, only three studies 10,40,52 performed an allometric test (body mass), and four studies 10,39,45,52 reached the clinical dose of alendronate for osteoporosis treatment, 70 mg/week, 10 assessed by the metabolic dose.
The methodological bias and dosage limitations do not allow drawing conclusions about the efficiency of a drug.So, this should be the starting point of an animal study that aims to test the efficancy of a drug.At the alendronate dose of 0.05 mg/kg/ week by oral gavage, 47 animals were about 300-fold underexposed and at a dose of 2.5 mg/kg/ day given subcutaneously, 50 animals were 93-fold overexposed.Can we extrapolate these results to humans?Doses used in these studies were far from relevant to the effective dose used in humans.One very important aspect to consider in normalizing a drug dose is the absorption concentration in the bloodstream.Alendronate given subcutaneously is nearly 100% absorbed, while in oral gavage, its absorption is about 1%. 2,62Maahs et al. 47 did not reach the clinical dose conversion at the dose of 0.05 mg/ kg administered weekly, by oral gavage, referencing Lehman et al., 63 who employed the same dose daily instead of weekly.Researchers should be aware to establish the clinically equivalent drug dosage by a correct allometric test and, whenever possible, to assess the serum levels.
Seventeen out of nineteen studies performed h i stolog ic a ss e ss ement s. 10,11, 37-39,41-4 3,4 5 -53 Te n reports, 10,38,42,43,46,[49][50][51][52][53] which described osteoclast characteristcs, revealed some functional impairment with cell activity reduction caused by alendronate.Once adsorbed onto bone mineral surfaces, due to its high afinity for hydroxyapatite, BPs come in close extracellular contact with osteoclasts.During the bone resorption process, BPs dissociate from the bone surface, followed by intracellular intake into osteoclasts by fluid phase endocytosis. 64In the cytoplasm, alendronate blocks the formation of intermediates along the mevalonate biosynthesis pat hway.Sp e c i f ica l ly, it i n h ibit s fa r ne syl pyrophosphate synthase (FPPS), a key enzyme in the mevalonate pathway that generates isoprenoid lipids, farnesyl pyrophosphate (FPP), and geranylgeranyl diphosphate (GGPP), utilized in sterol synthesis and in the post-translational modification of small GTPbinding proteins, essential for osteoclast function.Inhibition of FPPS impairs the prenylation process, thus causing alterations in important osteoclast functions, including cytoskeletal arrangement, membrane ruffling, trafficking of intracellular vesicles, and apoptosis. 2he findings of this review corroborate those obtained for the toxicity effects of alendronate on osteoclasts.Osteoclast morphology alterations were seen at the socket healing site after alendronate intake, including smaller 51 and atypical 50 cells with abnormal nuclei 43,46,51 and lack of a ruffled border. 51Reduction in osteoclast number, 38,43,49 function, 10,38,43,46,[49][50][51] and resorbed lacunae on bone surface 10,38 were also described.Additionally, the increased number of apoptotic osteoclasts was verified in the alendronate group. 50In fact, bone remodeling is substancially affected by osteoclast impairment.Twelve studies 10,11,38,41,43,45,46,[49][50][51][52][53] showed that bones in the alendronate group became more dynamic in terms of bone remodeling and bone resorption, compared with the controls.As a consequence, there is retention of the interseptal bone height followed by a higher volume, 10,41 increased thickness of the buccal and lingual alveolar sockets, 38 and a detectable clear boundary between the alveolar bone and new bone. 41,51It is difficult to separate bone remodeling and bone apposition rates.This is because suppressed osteoclasts may directly or indirectly influence bone formation.2,53 Alendronate also reduced the eroded surface of interalveolar septum by 90%.
that the histologic analysis of the alendronate group revealed that the newly formed bone lacked the bone-like fiber bundle after 14 days of healing, and it was also revealed that collagen content was reduced in alendronate specimens at 21 days after extraction, suggesting a compromised collagen production. 51The woven bone was quantified in four studies. 10,43,46,50Three of them 10,43,46 detected less woven bone apposition rates at alveolar bone healing sites in alendronate-treated animals.Aguirre et al. 10 showed that alendronate intake decreased 55% and 75% of woven bone volume compared to the control group, at moderate and high dosages, respectively.Taking into account post-extraction socket healing, according to Araújo et al., 65 these findings suggest that alendronate therapy delays the socket healing process, extending the inflammatory phase and postponing the proliferative phase.Four reports 11,45,49,50 in this review corroborate the increased inflammatory response, posing a challenge to alendronate exposure in the early phase of socket healing.Impairment in vascular sprouts 10,11,41,50 and lymphatic vessels 49 may be the reasons for the delayed clearance and sterilization processes at the healing site, leading to a delayed tissue granulation production and its replacement by a provisional connective tissue matrix.Additionally, alendronate therapy also affected ephitelial coverage in seven reports, 11,41,45,47,50,52,53 leading to a loss of mucosal integrity associated with bacterial infection.The toxicity effect of alendronate on the oral epithelium has been described, 5 and this is one of the main reasons for ONJ development.Five studies out of seven 11, 41,42.45,50identified the presence of osteonecrosis at socket healing sites associated with alendronate after tooth extraction, and eight studies 10,37,41,42,45,46,50,52 showed higher levels of empty osteocyte lacunae in the socket walls and interseptal bone, which is related to suppressed bone remodeling. 27he quality assessment of eligible studies in this systematic review was very hard to accomplish due to the lack of information provided by the authors.Many details regarding sequence generation, allocation concealment, and animals losses, are often unreported and were not recovered.To improve evidence-based animal experimentation, the authors should utilize a collaboration tool based on the Cochrane RoB tool 66 for randomized clinical trials to enhance the efficiency of translating animal research results into clinical practice.
The results of this systematic review should be interpreted with caution mainly because the study design has some important limitations.For instance, this review included studies aimed at developing the BRONJ animal model utilizing the tooth extraction model and also articles dealing with management of bone remodeling after alendronate treatment.Therefore, of the wide variation in alendronate dosage and differences in the route of administration hinder the comparison of the effects of alendronate on the extraction socket.Besides, the heterogenous outcomes (animal age and strains, teeth extracted, measurements of outcomes, etc) of the included studies might also limit inferences about the effect of alendronate on socket healing.Therefore, more studies are needed to elucidate the potentially deleterious effect of alendronate on socket healing after tooth extraction in animal models.

Conclusion
In summary, this systematic review identified that alendronate monotherapy negatively affects the early phase of wound healing after tooth extraction.It seems that alendronate affects the oral skeleton differently from other regions of the body.The reasons for that remain unclear and future research is needed to better understand the effects of alendronate on socket healing.

Figure 1 .
Figure 1.Flowchart of the study according to the PRISMA statement (2020).

Table 2 .
List of studies excluded from phase 2. Histopathological Examination of the Effects of Local and Systemic Bisphosphonate Usage in Bone Graft Applications on Bone Healing.Journal of Maxillofacial and Oral Surgery.2021;20(1):144-8.

Table 3 .
Summary of the selected studies in this systematic review.

Table 4 .
Summary of the selected histologic assessment.The effects of sodium alendronate on socket healing after tooth extraction: a systematic review of animal studies Braz.Oral Res.2024;38:e038The effects of sodium alendronate on socket healing after tooth extraction: a systematic review of animal studies