Pulpitis

No. Where the pulp is diagnosed as reversibly inflamed, removing the cause, treating the decay, replacing a failing restoration, addressing the source of irritation, may allow it to settle without root canal treatment. Where it is diagnosed as irreversible, root canal treatment or extraction are the usual options. The diagnosis determines the treatment, which is why the testing matters.

Not necessarily, and this is one of the more dangerous assumptions in dentistry. Pain from pulpitis can cease because the pulp has died, at which point the tooth is not healed but the source of the pain has stopped signalling. Infection can then progress into the surrounding bone with few symptoms for a period. A tooth that has hurt significantly warrants assessment even if the pain has gone.

By combining information: your history of the pain, its character and duration, response to cold and heat, electric pulp testing, response to tapping, examination for decay and cracks, and radiographs. No single test decides it. Combining several tests is also why the diagnosis is sometimes provisional, with a plan to reassess, which is a legitimate approach instead of uncertainty.

Antibiotics do not treat inflammation of the pulp. The pulp is inside the tooth with limited blood supply. The problem is mechanical and infective at a site antibiotics do not reach effectively. Treatment addresses the tooth itself. Antibiotics have a role in specific circumstances such as spreading infection, but they are not a treatment for pulpitis and do not remove the need for definitive treatment.

Several factors are commonly suggested, including lying flat and fewer distractions from the sensation. Night pain like this is a recognized pattern instead of an unusual one, and it is one of the features associated with irreversible pulpitis. If pain is waking you, that is worth mentioning specifically when you describe the history, because it is diagnostically relevant.

Yes: trauma, a crack that isn't visible on examination, cumulative effects of a deep old restoration, or wear exposing dentine can all inflame the pulp without an obvious cavity present, which is exactly why diagnosis relies on testing and history, not assuming a visible cavity must be present for pulpitis to be the explanation for pain.

Not reliably at home: both can produce pain affecting upper back teeth, and distinguishing them properly requires the same testing a dentist performs (cold testing individual teeth, checking for congestion patterns, examining for dental causes), so self-diagnosis risks missing the actual source. An assessment is the only reliable way to sort out which is responsible.

The response depends on the stage. Some severely inflamed or already-dying pulp can show a diminished or absent response to cold testing compared with a healthy tooth, which is itself diagnostically informative, so the pattern of response (or its complete absence) across several tests is what a clinician is assessing instead of a single simple pass-or-fail result.

Molars are somewhat more frequently affected simply because they carry more, and often older, restorations from a lifetime of chewing forces and are more prone to decay in their deep grooves. Pulpitis can develop in any tooth given the right cause, deep decay, a crack, trauma, so tooth position is a risk factor tied to typical causes instead of an inherent vulnerability of molars specifically.

Yes, in principle: sustained heavy forces from grinding can contribute to microscopic cracking or cumulative stress on a tooth that eventually irritates the pulp even without decay being the primary driver, which is one more reason unmanaged grinding is worth addressing generally, though it is a less common standalone cause compared with decay, cracks and trauma.

Not directly, since pulpitis in one tooth is generally caused by something specific to that tooth (its own decay, its own crack, its own restoration history), not a contagious or spreading process, though if the underlying risk factor is broader, such as generalized decay risk from diet or dry mouth, that same risk factor could independently affect multiple teeth over time.

Pain perception generally can be influenced by stress and anxiety, which may make an already painful pulpitis episode feel more intense or harder to cope with, though stress itself is not a cause of the underlying pulp inflammation: addressing the dental cause remains the actual treatment, with stress management being, at most, a supportive comfort measure alongside it.