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Bacterial infections of the tooth and the surrounding tissues progress rather slowly,

but every step is so much more severe than the previous one.

Cariogenic bacteria will first tear enamel down.

Then they'll bore through dentin.

When they or their toxic waste get into the pulp, pulpitis occurs.

Without immediate treatment, pulpitis can cause irreversible damage and require a root

canal.

If no treatment is performed, the pulp will eventually die off through necrosis.

At that point, the tooth is considered dead, and in essence, it becomes a staging area

for bacteria to spread further.

Our immune system will, at that point, try to stage a defense around the apices of the

dental root.

We call that "battlefield" apical periodontitis, which is one of the periapical lesions.

The primary form of defense our body has against infection is the polymorphonuclear leukocyte,

also known as the neutrophil.

It is the finest soldier serving our body, and its task is to locate and destroy microbes

that intrude into the body, wherever that might be.

This is usually a very effective force, and most of the times sufficient.

When an infection occurs, neutrophils will mobilize in huge numbers, head to the site

of infection, and leave the circulatory system, searching for bacteria to destroy.

They achieve this through three methods.

First is degranulation, where neutrophils release a bunch of granules containing various

enzymes, that hurt bacteria.

Then, they will use neutrophil extracellular traps, or NETs, to immobilize the wounded

bacteria.

These are actually nets, made out of neutrophil DNA!

Finally, neutrophils will then gobble up the bacteria through phagocytosis as a final means

of its destruction.

All of this works really well, most of the time.

But, fighting infection is a bloody affair and many of the neutrophils perish during

the fight.

Macroscopically, the battlefield, containing neutrophil remains, released enzymes, NETs

and dead bacteria, makes up pus.

And a lot of it can accumulate, given the severity of the infection.

Enzymes from the pus will irritate the surrounding tissues, creating an acute phase of apical

periodontitis.

The accumulation of pus is called a periapical abscess, as it surrounds the root.

This abscess can eventually form a sinus tract, which is a narrow passageway that extends

from the abscess to the mouth, through which the pus can drain out.

The periapical abscess can also progress into a periapical cyst, which is when fibrous tissue

and immune cells surround an area of chronic infection containing pus.

In less fortunate cases of periapical lesions on the maxillary teeth, the cyst can form

a fistula to the maxillary sinus, causing a severe case of sinusitis.

If the external drainage fails to happen, and the cyst or abscess continues to grow,

the lesion might progress to osteomyelitis, which is the inflammation of the underlying

bone, or cellulitis, which is the inflammation of the throat.

One severe form of cellulitis is called Ludwig's angina, where the inflammation of soft tissues

is so severe, it may lead to death through suffocation.

Treatment of periapical lesions usually involves antibiotics to curb the infection.

Then, an endodontic therapy is performed where the decaying pulp is removed and the abscess

is drained.

The pulp space gets thoroughly cleaned and disinfected, while the tooth crown is repaired,

allowing the dead tooth to continue doing its mechanical function of chewing.

Endodontic therapy has a high success rate, however, the treated tooth can sometimes reinfect

and an extraction may be required.

All right, as a quick recap.

Periapical lesions are inflammatory in origin, and involve apical periodontitis, which may

evolve into periapical abscess or a periapical cyst.

Abscesses can drain into the mouth or cause cellulitis.

Treatment involves antibiotics, pus drainage, endodontic treatment of the tooth, and failing

all that, extraction of the affected tooth.

For more infomation >> Periapical lesions - causes, symptoms, diagnosis, treatment, pathology - Duration: 5:26.

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Arsenal legend says fans may turn on Unai Emery over treatment of one player - News Today - Duration: 1:55.

Unai Emery is running the risk of making Arsenal fans "twitchy" over a lack of progress in the Mesut Ozil situation, according to former Gunner Lee Dixon

The German has only made one start for the club since Boxing Day, with a variety of illness and injury issues blamed for his absences

Emery has challenged the playmaker to produce the consistency required to keep him in the side but Dixon thinks that, having already proven that he isn't going to be pushed around by Ozil, Emery now has to get hold of the situation

"It's going to take time," Dixon told the 5 Live Football Daily podcast . "I know it's an easy thing to say, but a new manager coming in has got to be given time as well and he's had his handcuffs on as well behind his back, he's got the problem with Ozil

"I thought he's dealt with the Ozil situation pretty well, to be honest, with the media situation and how it's been

How he's talked about it and how he's left him out. "But now the fans have started to get twitchy saying: 'look, you've done that little bit of keeping him out the side and then trying to educate him on what is needed to get in the side, but we don't care anymore

"We just want some quality in there. "Because they've seen the likes of Alexis [Sanchez] leaving the club, and they've seen Ramsey leaving in the summer, and they're now looking and saying: 'where is the creativity from midfield?' "That's a real big problem for Arsenal at the moment

" Read More Mirror Football's Top Stories

For more infomation >> Arsenal legend says fans may turn on Unai Emery over treatment of one player - News Today - Duration: 1:55.

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New breakthrough treatment for women with hardest-to-treat breast cancer - Duration: 9:08.

New breakthrough treatment for women with hardest-to-treat breast cancer

An experimental 'magic bullet' drug has the potential to change the way women are treated for one of the most deadly forms of breast cancer, an expert has said.

Sacituzumab, is an antibody that zeroes in on cancer cells. Like a homing missile, it delivers a 'warhead' in the form of a potent chemotherapy drug. Since it directly targets tumours while avoiding healthy cells, side effects are kept to a minimum.

In a clinical trial involving 108 women with triple-negative breast cancer that had spread around the body, the infused drug caused 'significant' tumour shrinkage, researchers reported.

The women had all previously failed to respond to two or more previous treatments. All had a poor prognosis. Overall, a third of the patients responded to the drug and typical survival time was 13 months.

Nine long-term responders remained free of any disease progression for more than a year.

Senior investigator Dr Kevin Kalinsky, from Columbia University, New York, said: 'I think this drug has the potential to change practice, because the data looks so compelling, even with the relatively small number of patients in the trial.

There's an unmet need for patients with metastatic (spreading) triple-negative breast cancer, and we see significant tumour shrinkage with this new therapy. Triple negative breast cancers are notoriously hard to treat.

They are impervious to normal types of hormone therapy and drugs that target the cancer-fuelling HER-2 protein.

The new drug is also being tested against other types of breast cancer as well as bladder and prostate cancers, said researchers writing in the New England Journal of Medicine.

During the trial only 3 percent of patients stopped taking the drug due to adverse side effects. The main effects seen were hair loss, diarrhoea and fatigue.

Dr Kalinsky added: 'Having smaller tumours can be incredibly meaningful to a patient's quality of life. When tumours shrink, patients are more likely to experience improvement in symptoms, like pain.'.