Effects of metformin on the bioactivity and osseointegration of dental implants: A systematic review.

Dental implants are prosthetic devices that are surgically placed in direct contact with the jawbone to support intra-oral functions and esthetics. Diabetes mellitus may contribute to peri-implant bone loss. During the last few years, there have been attempts to reduce this bone loss and improve the survival rate of implants. Metformin, an anti-diabetic drug known for its osteogenic properties, is thought to prevent peri-implant bone loss in diabetic patients. Although several studies have been conducted to study metformin's effect on diabetic and non-diabetic study models, no systematic review has analyzed and summarized these studies critically. Therefore, the objectives of this systematic review were to summarize the outcomes of these studies and critically appraise them. Seven studies were included in this systematic review. Four studies used only animal models, two used both animal and cell culture models, and one used only cell culture studies. The general characteristics and outcomes of the included studies were summarized, and Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines were used to assess the quality of the animal studies. In vitro studies indicate that metformin may induce stem cells to undergo osteoblastic differentiation to produce a higher amount of bone and may also improve osseointegration. Nevertheless, several studies had potential sources of bias. Therefore, it is recommended that emphasis be placed on increasing the quality of future animal studies and human trials to determine the effects of metformin on the osseointegration of dental implants. Future studies are needed with adequate follow-up to evaluate the efficacy of metformin in improving the osseointegration of dental implants.

Recrudescence of severe polyneuropathy after receiving Pfizer-BioNTech COVID-19 vaccine in a patient with a history of eosinophilic granulomatosis with polyangiitis.

A middle age man with a history of diabetes mellitus type 2, hypertension, migraine and eosinophilic granulomatosis with polyangiitis (EGPA) with polyneuropathy in remission presented with paresthesia and motor weakness soon after receiving the Pfizer-BioNTech COVID-19 messanger RNA (mRNA) vaccine. The patient had polyneuropathy 10 years ago secondary to EGPA, which had resolved. EGPA was diagnosed on the basis of typical symptoms and positive sural nerve biopsy. Five days after receiving the first dose of COVID-19 vaccine, he developed heaviness and reduced dexterity of both the upper extremities, which progressed to patchy and asymmetric motor weakness of all four extremities. Given the lack of clear alternative explanation after a thorough work up, recrudescence of underlying asymptomatic polyneuropathy due to a possible reaction to COVID-19 mRNA vaccine was considered although a temporal association with vaccine dose does not prove causality. He was treated with corticosteroids with slow improvement of his symptoms.

Sternalis. An anatomic variant of chest wall musculature.

OBJECTIVE: To study the prevalence of sternalis muscle in the Kingdom of Saudi Arabia (KSA) and resolve the question of its genesis by studying the innervation of this uncommon variant of anterior chest wall musculature. METHODS: A morphological study of 75 adult cadavers of both sexes was carried out over a 5-year period by macroscopic dissection. We also retrospectively studied the medical records of 1580 adult females who had undergone screening and diagnostic mammographic imaging at King Khalid University Hospital, Riyadh, KSA, from 1997 to 2001. RESULTS: Out of 75 cadavers studied, 3 cases of sternalis muscle were observed. Two adult male cadavers had well developed bilateral sternalis muscles whereas one female cadaver exhibited right sided unilateral sternalis. All 5 sternalis muscles were positioned vertically, in a parasternal position superficial to the medial part of pectoralis major and innervated by branches of intercostal nerves. None of the 1580 women, however, who had undergone mammographic imaging were found to be sternalis positive. CONCLUSION: Consistent with other geographic populations of the world, the frequency of sternalis in KSA is approximately 4%; however, its innervation by the intercostal nerves, as observed in our study is not common. This study highlights the need for familiarity with sternalis, which may mimic a focal density in medial breast craniocaudal mammograms and may be encountered during reconstructive surgery of breast and chest wall.

Variations in the subclavian-axillary arterial system.

OBJECTIVE: The objective of this study is to report on the subclavian axillary arterial system variations observed in the dissecting room. METHODS: The morphological study of 106 formalin fixed upper limbs of adult human cadavers of both sexes was carried out at human anatomy laboratory of College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia over a 5 year period, to observe the distribution pattern of the subclavian axillary arterial system. RESULTS: The arterial variations in the upper extremities are quite common and may occur at the level of the thoracic outlet, axilla, arm, cubital fossa and the hand. In the present study, the anomalous topographic pattern of the subclavian axillary arterial system was revealed in 7.5% of the cadavers, whereas 92.5% exhibited classical pattern of the regional arterial anatomy. The study showed: 1. An aberrant right subclavian artery arising from the arch of aorta, distal to the left subclavian artery. 2. A bilateral common subscapular-circumflex humeral trunk (3.8%) emerging from the 3rd part of the axillary artery (branching into the circumflex humeral and thoracodorsal arteries. 3. A bilateral thoracohumeral trunk arising from the 2nd part of the axillary artery (1.9%) and branching into the lateral thoracic, circumflex humeral, subscapular and thoracodorsal arteries. These anomalies were accompanied by anomalous insertion of flexor digitorum superficialis muscle, a bilateral digastric muscle formed by the abductor pollicis longus and brevis, and an anomalous formation of median nerve by 3 roots. CONCLUSION: The aberrant right subclavian artery associated with right non-recurrent laryngeal nerve and variant branching pattern of the axillary artery are of interest to anatomists, surgeons and radiologists and suggested that these anomalies must be evaluated pre-operatively.

Variations in the subclavian-axillary arterial system.

OBJECTIVE: The objective of this study is to report on the subclavian axillary arterial system variations observed in the dissecting room. METHODS: The morphological study of 106 formalin fixed upper limbs of adult human cadavers of both sexes was carried out at human anatomy laboratory of College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia over a 5 year period, to observe the distribution pattern of the subclavian axillary arterial system. RESULTS: The arterial variations in the upper extremities are quite common and may occur at the level of the thoracic outlet, axilla, arm, cubital fossa and the hand. In the present study, the anomalous topographic pattern of the subclavian axillary arterial system was revealed in 7.5% of the cadavers, whereas 92.5% exhibited classical pattern of the regional arterial anatomy. The study showed: 1. An aberrant right subclavian artery arising from the arch of aorta, distal to the left subclavian artery. 2. A bilateral common subscapular-circumflex humeral trunk (3.8%) emerging from the 3rd part of the axillary artery (branching into the circumflex humeral and thoracodorsal arteries. 3. A bilateral thoracohumeral trunk arising from the 2nd part of the axillary artery (1.9%) and branching into the lateral thoracic, circumflex humeral, subscapular and thoracodorsal arteries. These anomalies were accompanied by anomalous insertion of flexor digitorum superficialis muscle, a bilateral digastric muscle formed by the abductor pollicis longus and brevis, and an anomalous formation of median nerve by 3 roots. CONCLUSION: The aberrant right subclavian artery associated with right non-recurrent laryngeal nerve and variant branching pattern of the axillary artery are of interest to anatomists, surgeons and radiologists and suggested that these anomalies must be evaluated pre-operatively.

Sternalis. An anatomic variant of chest wall musculature.

OBJECTIVE: To study the prevalence of sternalis muscle in the Kingdom of Saudi Arabia (KSA) and resolve the question of its genesis by studying the innervation of this uncommon variant of anterior chest wall musculature. METHODS: A morphological study of 75 adult cadavers of both sexes was carried out over a 5-year period by macroscopic dissection. We also retrospectively studied the medical records of 1580 adult females who had undergone screening and diagnostic mammographic imaging at King Khalid University Hospital, Riyadh, KSA, from 1997 to 2001. RESULTS: Out of 75 cadavers studied, 3 cases of sternalis muscle were observed. Two adult male cadavers had well developed bilateral sternalis muscles whereas one female cadaver exhibited right sided unilateral sternalis. All 5 sternalis muscles were positioned vertically, in a parasternal position superficial to the medial part of pectoralis major and innervated by branches of intercostal nerves. None of the 1580 women, however, who had undergone mammographic imaging were found to be sternalis positive. CONCLUSION: Consistent with other geographic populations of the world, the frequency of sternalis in KSA is approximately 4%; however, its innervation by the intercostal nerves, as observed in our study is not common. This study highlights the need for familiarity with sternalis, which may mimic a focal density in medial breast craniocaudal mammograms and may be encountered during reconstructive surgery of breast and chest wall.