This studypretends to evaluate the beneficial effects of the treatmentwith growth hormone(compassive off-label use)on bone regeneration and osseointegration of dental implant surgeriesin elderly people.A total of 140 patients, between 35 and 82 years of age, undergoing dental surgery, receiving a total of 402 dentalimplants have been investigated. Informed consent was signed by all of them. From this group, 58 patients(31 malesand 27 females) received a total of 209 implants and weretreated with local growth hormone in the surgical bed during the procedure, and in 29 implants of this group,when surgical beds were more extensive also with daily systemic application for one month.

Another 82 patients between 35 and 82 years of age (39 males and 43 female) werealso submitted to implant surgery and received a total of 193 implants without growthhormone treatment. For the evaluation of results, a simple apical radiography was used.Osseointegration was determined by bone neoformation and density between and around theimplant coils. Study showed that growth hormone treatment was able to induce a statisticallysignificant decrease in the average time between the surgical approach and osseointegration of theimplant. The median value for treated patients was 82 days whereas the untreated needed amedian of 140 days. No differences were observed either regarding gender or groups ofage.

It was concluded that in all age and gender groups the reduction of theosseointegration time was very significant when growth hormone treatment was used.

Keywords:growth hormone, implants, osseointegration

GH, Growth hormone; PTH, parathyroid hormone; OPG, osteoprotegerin; PRGF, plasma rich in growth factors

The great desire of nearly all people is to have a long and healthy life, which does not meanto add more years to the lifespan, but also to increase the quality of life in said years. Starting from the age of 40 a decrease in several hormones can be observed that seems to be related to the aging process. The replacement therapy with these hormones at physiological doses and after an individual evaluation to prove that the beneficial effects¹ are always greater than the possible adverse effects could be a strategy to delay the consequences of aging. Although no hormone can be recognized undoubtedly as a "rejuvenating" agent or that it may prolong life, some of its actions may be beneficial.² The possible treatment of elderly people usingreplacement therapy with growth hormone (GH) was first demonstrated in the paper of Rudman et al.³ Actuallythe possibilities of GH replacement therapy for the aging process  is showing a steady increase.

GH promotes body growth during infancy through puberty, inducing fundamentally an increase inthe length of long bones acting on the chondrocytes of the conjugation cartilage (or growth plate), although it also stimulates the growth of soft tissues. In childhood, a deficit in the secretion of GH leads to pituitary dwarfism, whereas its hypersecretion causes gigantism. In adults, excessive production of GH leads to acromegaly, whereas its deficit leads to a syndrome characterized by a set of factors leading to early atherosclerosis and an increased risk of cardiovascular diseases.⁴ 

Pulsatilesecretion of GH reaches a peak during puberty, a period in which its pulse amplitude is greatest during slow-wave sleep.³ This phase is the most important of all stages of sleep due to its influence in the GH increase. With aging, sleep fragmentation occurs and changes in circadian rhythms appear, which leads to a decrease in slow-wave sleep. This leads to a decrease in melatonin, GH andInsulin-Like Growth Factor1 (IGF-1) levels.⁵ From the fourth decade of life onwards a decrease of GH secretion levels can be observed, converting the majority of elderly people into GH deficient individuals (SDGA). 

One of the actions of GH is the stimulation of the formation and/or remodelling of bone tissue, and the increase of bone density. Recent studies justifies that GH can be used in the treatment of osteoporosis in adults with GH deficiency or also during a period of healthy aging.⁶ In addition, it has been shown that continuous treatment over a period of time in patients with GH deficiency is also able to increase bone mineral density and is therefore recommended as a treatment to obtain bone maturation in children in need of it.⁷ Another possibility of GH administration is to contribute to accelerate the process of osseointegration in fractures.⁸

Among the actions performed by GH are the formation and remodelling of the bone tissue. The overproduction of GH (achromegaly) is accompanied by an increase in bone mass⁹ whereas in adults with GH deficiency the bone mineral density is decreased,¹⁰ and these patients develop a higher risk of osteoporosis.¹¹ In fact, both local¹²and systemic⁸ GH administration is able to accelerate the bone remodelling process. 

Several studies have demonstrated the possible utility of GH as a coadjuvant in the consolidation of fractures. Thus, the administration of exogenous GH to rats in which an experimental tibial fracture had occurred was capable of increasing the rigidity and load capacity of the fractured bone.^13,14These positive effects are also observed in older animals.^15,16All these data allow hope for its potential role in the consolidation of complicated fractures, either by nature of injury or because the individual responds poorly to conventional treatment when having advanced age or osteoporosis.^17,18,19 

There are many studies that have proposed the administration of GH for the treatment of osteoporosis, since it has been proven that it is able to accelerate bone remodelling both in patients with adult GH deficiency and in healthy elderly.^20,21Still with better results given in combination with Parathyroid Hormone (PTH).²² The administration of GH alone or combined with estrogens, is also able to reverse vertebral osteopenia in ovariectomized rats.²³ Also, in women in which osteoporosis is a serious problem, this beneficial effect has been observed, since the administration of GH in postmenopausal osteopenic women increases bone mineral density and markers of bone formation within 7 days of treatment. Similarly, replacement therapy for 12 months²⁴ or 24 months²⁵ in adults with GH deficiency also increases bone mineral density and remodelling markers. There is a recent and very important paper which followed menopausal women with osteoporosis for ten years, in which a very important effect has been observed with the treatment with GH.²⁶All this suggests that, probably in the near future, GH will be used alone or in combination with other drugs forthe treatment of osteoporosis.  

Similarly, several studies have shown that local administration of GH at the time of surgery favours the transcortical osseointegration of titanium implants in rabbits, both osteoporotic and non-osteoporotic,²⁷ allowing a glimpse of its use in the field of dentistry.

209 implants were placed using local GH in the surgical wound in 58 patients (31 men and 27 women) and 193 implants without GH in 82control patients, (39 men and 43 women)for comparison, in people between 35 and 82 years of age. 

Threaded implants of various diameters and lengths were used, both in external and internal connection, a single dose in local application in the alveolus of GH 2mg implantation (Somatropin - 10mg/1.5ml). In 29 implants with more extensive surgeries, systemic GH of 1mg (Somatropin 10mg/1.5mg) per day was administered 10 days before surgery and for 20 days afterwards.

When there was a need for bone growth or filling of empty spaces, agglomerated regeneration biomaterials were applied in a Plasma Rich in Growth Factors (PRGF) autologous fibrin clot. All the implants were placed with an open flap technique on the first time and on the second time, with an exposure of the implant, with the punch technique. 

All patients signed an informed consent, both in the placement of simple implants (without GH) and in those in which GH was administered.They were all informed about the benefits and the possible risks of the compassionate off label use of GH. 

For the evaluation of the results, the simple apical radiography was used, always with the same apparatus, film positioner, the same intensity to be as accured and standardized as possible, assessing the osseointegration by the neoformation and bone density around and between the turns of the implant's threading. Osseointegration occurs when the image shows a similar density to normal bone, with absence of hypodense zones; some hyperdense areas due to ankylosing might be present. 

A statistical analysis was carried out using the “t-student modified" adapted to situations of non-equality of underline sub population variances. The statistical analysis of the comparison of the three averages of the groups, by resorting to a model of analysis of variance to a factor (age) is not revealed feasible due to the small number of observations in the group over 70 years old. 

When GHadministration in single or multiple implant placement surgeries is used, the healing and osseointegration process is faster in time, (median time, 82 days vs 140 days) as compared to controls in which GHwas not used, as shown in Table 1.

In each of the Box Plot, Figure 1, three cases of “outliers" patients are identified in the right parts of the data distribution. The clinical study of the patients that generate these observed cases, revealed that there were other factors that could explain the relatively high time margin between placement and osseointegration. 

Figure 1 Box plot of the two situations, with or without GH-comparative analysis.

For the other patients, no deterministic factors were found to explain the remaining extreme values of time, observed between placement and osteointegration.

Consequently, robust estimates of average time and variance of the sample were obtained, between the various times of osseointegration, recalculating mean time and variance “truncated to the right” by excluding the three outlier cases, in each of the samples under study.

The exploratory analysis of Table 2 indicates that

1. The use of GH decreases theaverage time between implant placement and osseointegration.
2. There is a visible discrepancyin the evaluation of the absolute dispersion of the data in each of the situations
3. In eachcase the coefficient of asymmetry is less than one, which means, the data has a high degree of 

It can be seen that there is a very significant influence of the use of GH in the reduction of the osseointegration time of the implant (P< 10^-5),Table 3.

Comparative statistical study of ages with application of GH 

The previous analysis of these data seems to reveal a small but not significant difference in the effect of age on the mean times between placement and osseointegration when using GH, Figure 2. And the inter-quartile range is quite similarly for the tow first age group.

From Table 4, it can be concluded that there are nodifferences in the degree of reduction of the osseointegration time by GH in the different age groups, population of up to 50 years μ₁ and μ₂ in the group of 51 to 70 years.

Figure 2 Box-plot of the three age groups, with GH-comparative analysis.

Additionally, Table 5 shows the significant reduction of osteointegration times inall ages groups patients treated with GH, as compared whit those without GH, around 60 days.

Statistical comparative study of gender with application of GH 

When we compare women with less than or equal to 50 years of ageand women over 50 years of age on the action of GH taking into consideration that it is generally in this age group that hormonal alterations are likely to influence osseointegration, the data points to a non-significantdifference in the time of osseointegration in these age groups when subjected to treatment with GH, (p­­-value >0,10), Table 6.

Placement of implants with not enough bone 

Placing the implant in the bone cortex, but having aminimum amount of marrow, even if only on one side, the bone growth was verified both on the side that had marrow and on the other side, having bone growth both in thickness as in height (Figure 3). Where was placed 4 implants.

Figure 3 Bone growth around the implant with the use of GH.

Recovery of implants with Peri Implantitis 

In conjunction with biomaterials and PRGF, bone neoformation was verified, whether in growth or in vertical filling (Figure 4) around an implant with Peri Implantitis. Surgeries were performed on 6 implants.

Figure 4 Recovery of implant with periimpantitis.

Treatments with several stages 

In the 1st stage GH was not used and external scarring occurred in about 1 month and complete osseointegration at the end of 6 months, in the 2nd stage local GH was used and external scarring occurred in close to one week and complete osseointegration at the end of 2 months, in the 3rd stage local GH was used in the surgery and systemic GH (10 days before the surgery and 20 days after it , (in the case of  very extensive surgery of the upper hemiarcade with extractions and immediate placement of implants) external healing occurred in two weeks and osseointegration in 3 months (Figure 5). Twenty-nine implants were placed in 5 patients.

Figure 5 Use of GH at various stages of treatment.

Dental extraction and implant placement

External scarring and complete osseointegration is faster even when there is no complete closure of the wound due to lack of gingiva. There were 13 implants placed.The scarring and osseointegration is much slower (previous statistics) and vertical bone growth is not verified in premises with less bone, sometimes causing serious problems (Figure 6), and even when it has been years since the placement of the implants in areas of less bone, there is no bone neoformation or complete osseointegration (Figure 7).

Figure 6 Problems when implants are placed with lack of bone and without GH.

Figure 7 There is no new bone formation without GH.

Placement of implants with infectious lesions

GH treatment very quickly accelerates the growth and developmentof old lesions that were latent or hidden, generating a rapid rejection of the implant with bone loss in the corresponding space. This happened in 5 implants of 3 patients. 

It is known that from the fourth decade of life onwards there is a decrease in GH levels, making the majority of elderly people physiologically GHdeficient which is associated with muscle weakness, atherosclerosis, osteoporosis, etc.²⁸

GH and mainly IGF-I promotes bone growth, in a dose-dependent manner, by direct stimulation of metaphyseal chondrocytes.^29,30When GH is administered locally, it takes action on the chondroprogenitor cells, promoting their differentiation and proliferation, whereas IGF-I acts on already mature chondrocytes, stimulating both their proliferation and matrix synthesis.³¹ IGF-I and II are the most abundant growth factors in bone and are able to stimulate the proliferation and differentiation of osteoblasts,³²At the same time as they enhance collagen synthesis and inhibit its degradation. The actions of these IGFs are regulated to a certain extend by the Insulin-Like Growth Factor-Binding Protein 3 (IGFBP-3), whose in vivo production is under the direct control of GH.³¹

It has been often observed that both resorption and bone formation show high values in young subjects with high levels of GH,^8,21concluding that GH activates bone remodelling, by increasing the differentiation of osteoclasts and osteoblasts, and the same can be obtained with the treatment with GH.

GH is very important in the longitudinal growth of bone acting on the growth plates and stimulating the differentiation and proliferation of osteoblasts. However, in the osseointegrationprocess of titaniumimplants placed in situations of osteopenia/osteoporosis, its effects haven’t been studied much. The systemic application of the hormone on bone physiology has been widely evaluated in animals^33–39with satisfactory results in fracture healing, bone distraction, situations of osteopenia and osteoporosis, and in GH deficiencies.

GH is an anabolic hormone that stimulates not only osteoblasts proliferation and differentiation,⁴⁰ but also osteoclasts,⁴¹ thus, GH is capable of stimulating bone turnover.⁸ GH is also able to enhance bone fracture repair, both in young^16,42and old animals,¹³ when given systemically. Hedner et al.⁴³applied GH in jaws of rats with bone defects, demonstrating that there was an increase in bone formation with application of local GH for 4 weeks. In case of fractures or osteotomy, GH has shown also positive effects on the repair, as proven by Cacciafesta et al.,⁴⁴which have shown that in the animals treated with GH there is a significant increase almost doubling the volume of newformed bone as compared with the placebo group,Actually  GH administration could be effective in the consolidation of hip fractures in humans.⁴⁵

Several authors have found an increase in cortical thickness after treatment with GH not only in normal rats,⁴⁶ but also in aged rats,^15,16in ovariectomized rats,²³ and also in old ovariectomized rats^35,47Accordingly, with Andreassen and Oxlund,¹⁸ GH treatment does not seem to have effects on trabecular bone in absence of linear growth.

In addition, when GH administration has been associated with other hormones, such as PTH, additive effects on vertebrae have been observed in old ovariectomized rats, in which an increase in both cortical and trabecular mass was also seen. GH seems to induce a subperiosteal apposition whereas PTH induces an endosteal and cancellous deposition.¹⁷

Elena Martin Monge in her study in 2009⁴⁸ valued the local application of growth hormone on the process of osseointegration of a titanium implant of threaded surface in the tibia of ovariectomized rabbits submitted toa hypo-calcic diet (experimental osteoporosis) and in the tibia of healthy rabbits.The "impulse effect" of the application of local GH would produce an initial acceleration of intracortical remodelling, starting with resorption and continuing with bone formation. Following the model proposed by Tresguerres et al (In which 4 U.I. of rhGH were applied in the surgical process of inserting titanium plates, and in other casesbicortical screw implants).Local application of GH increases osteoid tissue formation and bone growth in animal models.^49–54

Oxlund & Andreassen⁵⁵injected for 14 days, 2 or 20mg/Kg/day of rhGH on the surface of the diaphysis of the intact tibia of ten month old rats and ina fracture healing process.After 21 days an increase in bone load capacity and strength was found, as well as in the size and volume of the fracture callus; after 98 days, the ability of bone loading, versus a control group, remained increased.

In humans, the application of GH activates bone remodelling units, increasing the differentiation of osteoclasts and osteoblasts, and once activated, they go through a "complete" remodelling cycle⁵⁶. It is known that the effect of treatment with GH in adults, not only markedly accelerates bone turnover by increasing the activation of new bone metabolic units, but also stimulates periosteal bone apposition, which entails the enlargement of the bone width.

The combination of these two different effects can, simultaneously, increase both the bone mineral content and the bone projection area.

The systemic application of the hormone has been studied in humans^56–60 with satisfactory results in fracture healing, osteodistraction, situations of osteopenia and osteoporosis, and GH deficiencies.Already in 1998, Wüster et al.⁵⁶carried out a review on the application of GH in healthy individuals; in patients with osteoporosis, in elderly people and in cases of GH deficiency (GHD) (in which the bone mass is decreased). They observed that after administering GH to the patients with GHD there was an increase in bone turnover (remodulation), mineral density initially decreased, during the first year of treatment, due to the increase in bone remodelling.

In the same way as other authors^52–54the local application of lyophilized GH was carried out directly on the implant bed, soaking with the blood clot. In addition, since administration is in a single dose, side effects would not occur.

Data obtained in the present study are consistent with previous ones showing improvements achieved by GH administration regarding biomechanical properties of the bone.^18,35,46

If we try to investigate the pathways by which GH is able to stimulate bone formation, it has been demonstrated that it is able to stimulate the differentiation from mesenchymal stem cells towards the osteoblast lineage, even in aged animals.⁶¹

In addition, GH seems to modulate the activity of Runx2, a transcription factor that is needed for chondrocyte maturation and osteoblasts differentiation.⁶²

 GH is able to enhance osteoclast activity,⁶³but it is also capable to increase osteoprotegerin (OPG), an endogenous inhibitor of osteoclast differentiation and activation. The effect is exerted through its binding to RANKL, preventing its union to RANK and leading to a decrease of osteoclastogenesis.⁶⁴

The age related decline in GH levels observed with aging, could lead to reduced plasma calcium levels, resulting in a compensatory increase of PTH, leading to an increase in bone resorption. Administration of GH could reduce the secondary hyperparathyroidism, since it can increase the intestinal calcium reabsorption,⁶⁵ increasing calcium availability by the bone. Furthermore, GH administration could also restore PTH levels, as demonstrated by Joseph et al.⁶⁶ in postmenopausal women with osteoporosis.

GH is able to stimulate angiogenesis,^67,68which is the first step in the osteogenic process. In another study from our group, GH was able to reduce in the aorta of old animal’s medium layer cross-sectional area that showed an increase, and to increase its relaxing responses which showed a reduction.⁶⁹

Also, Landin-Wilhelmsen et al.,⁵⁷ did find significant differences in BMD or BMC at the end of the study with 80 osteoporotic women who had previously received Hormone Replacement Therapy, and who were given for 18 months 1 u/day of GH, or 2.5U/day. They concluded that GH produced a delayed, prolonged and dose-dependent effect in postmenopausal osteoporosis, and that it could be used as an anabolic agent in the treatment of this disease.More recently Krantz et al.²⁶demonstrated also very positive effects of GH treatment for 10 years in osteoporosis of menopausal women.

In the reviewed papers, we have not found any study of the use of GH in osteoporotic subjects in which implants were placed with any type of surface covered.

In the scant literature found on local application of GH, this is done in the form of an osmotic pump or local subcutaneous injection^43,55,70and when used with implants, the authors consulted impregnated the surface of the implant, either titanium or ceramic, with the GH^49,51,71Downes et al.⁵⁰used a polymethylmethacrylate cement for local application, obtaining good results, but in their case, titanium implants were not used.

The safety of potential GH administration in aged people is controversial. Since the very important paper of Rudman et al.⁷²many elderly people have been treated with GH, mainly in the USA, for several “off label” indications including aging itself, and no report to our knowledge about any increase in cancer appearance has appeared until today.However, some side effects have been detected with GH treatment in adults as an increased risk for carpal tunnel syndrome, fluid retention or insulin resistance, but only when high doses of the hormone were used.^73,74

In this work carried out in dental implantology, it can undoubtedly be concluded that the use of GH is beneficial in healing and osseointegration, both locally and systemically, as demonstrated in the statistical study presented.In addition, the analysis by age groups showed a small difference, statistically significant, with slightly longer average times between implantation and osseointegration in the age group of 50 to 70 years.

In the comparative analysis of implant placement with or without GH, there is great evidence for the three age groups regarding the reduction of osseointegration times in patients treated with GH (p-value close to zero).In addition, a very similarly central spread of osseointegration time is verified for the first two age groups (patients aged <50 years and between 50 and 70 years). Which means, its application would be more advisable in the age group over 50 years.

When specifically studying women of over 50 years old, we observed that without GH there is a significant difference between the times of osseointegration and when GH is used, that difference does not exist, because the use of GH will compensate for its deficit that is verified from the fourth decade of life making its use more beneficial in this group of people.

However, it was also observed in this study for Clinical practice that with previous injuries the use of GH also exacerbated them more quickly. In the remaining situations there are indications of the beneficial influence of the GH in decreasing the average time of osseointegration, but the sample is very small in statistical terms, to do it with reliability, lacking studies that can be more statistically concluding.

None.

None.

None.

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