Post & Core Lab from China

Post and Core FAQ Guide

1. What is post and core?

A post and core is a method of restoring a tooth. When the amount of tooth tissue is insufficient, a post and core crown are required to preserve the traditional crown. A post is fixed in the prepared root canal, retaining the core restoration and retaining the final crown. Post and Core is used when a natural tooth (usually a molar) has a large carious area. Crowns cannot be supported by the remaining tooth. An alternative to this repair is an implant system, but it is quite expensive and time-consuming.

In this case, a simpler approach is to build a post and core as the prepared tooth. So the tooth can have enough area to support the crown or bridge. Post and core is a dental restoration treatment, sometimes performed after root canal treatment.

When most of the tooth’s structure has been removed, the column and nucleus can help hold the crown in place. Crowns are placed on teeth to protect them from further damage or infection.

2. When to use post and core?

In post and core surgery, the root canal must be free of the cavity or cavity that was originally filled with pulp (the root is still present). During root canal treatment, this post is sealed inside the root canal. So this post and core are done after root canal treatment.

Normally, dentists only recommend post and core surgery when more than 50 percent of the tooth’s original structure has been removed. In these cases, the column helps to mechanically fix the crown and nucleus. Post and core surgery should not be performed if there is enough remaining tooth structure to secure the crown.

3. What is the working mechanism of the post and core?

Post and core is a dental restoration when the tooth structure is insufficient to support conventional restorations. A small rod, usually metal, is inserted into the root space (root canal) of the tooth and protrudes a few millimeters from the root. This pole is called a post. This post is then used to hold the packing or core in place. Without this post, there would not be enough tooth structure to support the desired filling. Most of the time, this procedure is performed after the tooth has had root canal surgery, which requires a post-crown.

Considering that the tooth is ready for full coverage restoration, there needs to be sufficient residual tooth structure to preserve the restoration core. Columns are used when core recovery does not have sufficient retention. It’s important to remember that the purpose of this post is to preserve core recovery only. Instead of strengthening the tooth, this post weakens it by potentially causing a fracture of the remaining tooth structure. Exceptions may be when there is a thin remaining coronal structure on the tooth with the risk of the fracture using a post. In this particular case, it could be argued that a rigid post actually prevented the rupture of the thin crown structure.

Direct core repair involves the use of prefabricated piles to complete the core repair in one pass. These posts come in several forms: parallel-walled smooth cylindrical, parallel-walled helical, and helical. The posts are made of stainless steel, titanium, composites, and fibers. Precast piles can be divided into two broad categories: passive and active. Passive piles do not apply any stress to the roots when they are inserted, while active piles apply stress to the roots when they are inserted. The use of posts is associated with tooth fractures and eventual failure: more teeth with posts occur than teeth without posts.

With this in mind, we must take into account that the purpose of the post is to preserve the core while minimizing the risk of tooth fracture. Compared to screws that actively drive into the tooth and apply pressure to the remaining tooth structure, parallel-wall passive-fit posts are thought to minimize the chance of fracture, thereby increasing the risk of fracture. When choosing a post, it is important to keep in mind that the root will taper as the canal preparation moves towards the apex. Care should be taken not to over-prepare the apical part and preserve as much tooth structure as possible.

4. What are the pros and cons of post and core?

Below are the pros and cons of the post and core programs.

• Pros: The post-and-core procedure allows you to preserve your teeth, eliminating the need to extract and replace teeth, which can be expensive.
• Cons: Post and core procedures do not reinforce or strengthen teeth. In some cases, a post can stress or weaken your teeth over time.

5. How to prepare for post and core surgery?

You may need to stop taking certain medicines, such as aspirin (Bayer, Beverage), pain relievers, and blood thinners a few weeks before surgery. Most dentists recommend not smoking or drinking alcohol for at least 24 hours before surgery.

Your doctor may give you antibiotics before surgery to reduce the chance of infection.

You should also arrange for someone to take you home after your surgery. The anesthesia, sedation, or other drugs you receive during surgery may affect your reaction time. This means it may not be safe for you to drive afterward.

Follow your doctor’s specific instructions to prepare for your surgery.

6. What are the concerns of applying post and core?

The benefit of root canal implantation is improved crown retention. However, there are drawbacks, there is a risk of perforation during the preparation of the post space, the post also makes the tooth more prone to fracture, it makes future orthodontic root canal treatment more difficult, and finally, it is very destructive and requires Extensive removal of tooth tissue. The presence of the ferrule can increase the fracture resistance of the pile.

7. How long is a post and core?

In the manufacture of posts and cores, in order to provide adequate retention, the length of the post must be reduced to at least two-thirds of the length of the root canal (or not less than the height of the crown). The width of the pile should take into account the maximum strength and fracture resistance, but not be too wide, otherwise, it will lead to side penetration and root fractures.

It is important to leave at least 4 mm-5 mm of azalea glue at the apex of the root canal, even at the expense of longer posts, because the apical apex glue is anastomosed with the outer surface of the root within 4 mm of the root canal apex. If these lateral canals are not blocked by Dolby glue and the cement in which the Dolby glue is placed, the chances of microleakage and microbial penetration are greatly increased, thereby increasing the likelihood of root canal treatment failure.

It is not the length of the endodontic post that determines the retention of the core and eventual crown, but the length of the endodontic post that determines the length of the root structure of the surrounding bone. If the post is 16 mm long but extends only 4 mm into the root structure surrounded by solid bone, the prognosis for the repair is poor. Crown-to-root ratio consideration is essential for evaluating tooth crown lengthening procedures.

8. What is the process for applying for posts and cores?

Step 1 – Create a post space.

As a first step, your dentist will need to create a location (“alveolar space”) within your tooth where the socket will be nailed.

This prepared area will be inside the tooth’s root canal, which is filled (sealed) with a rubber-like compound called gutta-percha during root canal treatment.

Step 2 – Install the uprights.

Once the post space within the tooth has been created, the dentist must assess whether the particular post they choose to place will fit in the prepared socket.

Step 3 – Cement Pile.

Once the fit of the post has been checked, it’s time to glue it inside the tooth.

• What kind of material is used on post and core?

Historically, the type of cement used by dentists has rarely helped post-retention. The cement fills the perimeter of the posts but does not adhere to the posts or the teeth.

Dentists now have many different types of adhesives to choose from. However, even so, the physical characteristics of the post (its length, it’s own staying within its post space, etc…) still play a major role in achieving adequate post retention. (Using adhesives is unlikely to overcome the pitfalls of poorly designed piling systems.)

• How are the post and core applied?

This step is simple. Mix the cement well and apply it to all sides of the post. Your dentist may also apply a layer of cement to the walls of the tooth column inside the tooth.

The coated post is then gently inserted into the tooth so that it is fully seated in the space created for it. (Too fast or too much force can put too much pressure inside the tooth.)

Any excess cement is squeezed out. However, the timing of this step (before, after or during the cement setting period) varies depending on the type of cement used.

Step 4 – Add the core part of the post and core repair.

Once the cement of the column has been set, the core stacking portion of the restoration can be added to complete the crown stacking of the tooth.

The materials most commonly used for dental cores are simply conventional dental restorative materials, the most common being dental amalgam (silver filling material) or composite resin (dental bonding material).

Step 5 – Complete the tooth reconstruction.

Once the post and core placement process is complete, the tooth’s crown can be made just like any other tooth.

With this procedure, the size of the post that’s placed isn’t as much of a concern as the goal of minimizing the amount of internal tooth structure that must be removed to place it.

A smaller diameter post, and therefore a thicker root structure, reduces fracture risk for the tooth. In general, a post shouldn’t be larger than 1/3 the diameter of its root.

The post’s retention (resistance to being dislodged) generally correlates with the length it extends into the tooth’s root.

Ideally, the post should extend at least as far as the height of the crown. Ideally, it should extend about two-thirds of the root’s length. Nevertheless, 3/16ths of an inch or so of gutta-percha should remain undisturbed at the root’s tip in order to maintain a satisfactory endodontic seal.

Achieving all of the above (post diameter, post length) while avoiding procedural harm There can be challenges for dentists when dealing with these situations (root perforation, loss of endodontic seal integrity). Particularly when the root is small, curved, or has a noncircular cross-section.

9. What are the key factors leading to the success of post-core surgery?

As technology and research have advanced, this process has improved. The post was once cemented with zinc phosphate bone cement; now, with cement-based cement, the retention of the post is increased and the entire system is strengthened. While metal posts can be cemented with a variety of cement, the cementation of fiber posts within the pipe is advantageous as this can increase the strength of the system.

Other improvements to the post system include the materials used for posts. Traditionally, columns have been fabricated from dissimilar metals; however, current technology allows columns to be fabricated from resin and fibrous materials. These stakes can be used to set bone cement through the stake itself, which is more aesthetically pleasing and closer to the elastic modulus of the teeth. Also, some tout the flexibility of the postal system.

In any case, the keys to successful post and core repair revolve around certain fundamental factors. Posts should passively fit into a well-prepared post preparation of the appropriate length, preserving the most tooth structure possible. The column space should be clean and dry, and the column should be properly bonded with an adhesive system. The core is to be established to meet the requirements of preparing the tooth for restoration. Even with post and core restorations, the key to a successful full coverage restoration is to ensure that there is adequate ferrule over the remaining healthy tooth structure. While pillars and cores are important for the preservation of full coverage restorations, ultimately the remaining tooth structure will determine the success of the restoration.

Post and core have many variables in terms of systems, materials, and techniques used. Research supports different techniques and is somewhat vague in determining the ideal position and what the core needs. This is understandable because ultimately, the stakes and cores will be determined by each clinical situation presented. Dentists can use existing techniques and materials to create posts and cores that will best help preserve a full-coverage restoration and minimize damage to the teeth. As materials continue to evolve, our ability as dentists to create a better post and core systems will improve.

10. How are post and core created?

1) By using a drill.

Most dentists use (slow) dental drills to create the desired channel for the column.

Because gutta-percha is as vicious as soft rubber, the dentist’s drill will usually follow the path of the root canal through the gutta-percha without much resistance and without going off track.

To aid this process, the dentist may touch the gutta-percha with a heated instrument to soften it so that the process of drilling the tooth is easier and easier to perform.

2) Manual work.

A more cautious approach is for the dentist to heat the gums to soften them, then scrape them out with hand tools. The shape of the empty root canal is then improved by using a root canal file or dental drill.

This is a safer method because when the drill is used by itself to create post space, it always has a chance of going off track. In the worst case, a perforation (a hole drilled through the side of the root) may develop.

11. What are the common post and core in the market?

When a post and core are necessary, many factors are involved in determining how types are used and how the program is done. One of the oldest and most predictable techniques involves the use of indirect monolithic posts and cores. Posts and cores of this type are typically cast metal, which tends to be a precious metal such as gold. This pattern is created directly in the mouth with resin or wax. After the pipe is ready, use a starter stake in the pipe and surround it with pattern material to create a snug-fitting stake. Then, create a coronal section in the pattern material and shape it to the desired profile. The entire post and core pattern are removed from the tooth. A monolithic strut and core are then cast and glued to the teeth.

The advantages of this type of post and core include the fact that the post fits snugly in the tube space even if the tube is not round. The fact that the post and the core are one-piece ensures that the core cannot be separated from the post. However, indirect posts and cores require multiple visits and involve the use of non-aesthetic metallic materials, possibly manifested by ceramic restorations. The current trend is to use direct one-access post and core technology.

Precast posts and post cores take less time to place because they do not involve any laboratory work, and once the root canal treatment is complete, the post space is cleared of glue and can be inserted as soon as it is decided to use them. Once the prefabricated post is properly bonded into the post space, a core material such as dental composite can be filled around the bonded post. After the material has cured or has had a chance to set and properly form the crown preparation, an impression can be taken to create a false crown.

Metal prefabricated post systems are being replaced by fiber-reinforced composite resin post systems that are better able to resist untreated fractures of the dental substrate, such as vertical root fractures.

In cases where the post space is not a good match for prefabricated posts, cast posts and cores can be custom fabricated with teeth. Resin patterns are created by placing prefabricated plastic “burnt-out” posts into post spaces and a resinous material, such as Duralay resin, is used to build the teeth to the proper size. Once complete, the resin/plastic post pattern is removed from the tooth structure and attached to the gate former just like the crown wax pattern, so that it can be fabricated using lost wax techniques in gold, titanium or other metals A single cast post and core. Alternatively, plastic posts and polyvinyl siloxane impression materials can be used to make impressions of post spaces and dental arches and use to construct suitable posts in the dental laboratory.

12. What materials can be used for making post and core?

Posts can be made of non-metallic materials and metals.

In general, non-metallic piles have the ability to resist high stress without permanent deformation and fracture, so the incidence of root fracture is low. Non-metallic posts should not be used if there is not enough tooth tissue (ferrules). Healthy tooth tissue should be at least 1.5 mm from the nucleus. Non-metallic posts are also more aesthetically pleasing than metal posts because metal posts will glow in all-ceramic restorations, and non-metallic posts are optically closer to the tooth tissue (except for carbon fiber posts, because the material is darker). Non-metallic posts are easier to remove from teeth than metal posts if needed. Direct use of non-metallic columns is the most common use, but they can also be built in the laboratory.

Zirconia columns have high strength. However, they are brittle and have high modulus, which can lead to root fracture. It’s hard to delete these posts if needed. The zirconium pillars cannot be etched, resulting in difficulty in retaining the composite core.

Ceramic pillars are made of brittle material. Too strong these posts can cause root fractures. Removing a ceramic post can be difficult, if not impossible.

Fiber-reinforced resin is a form of non-metallic post that includes carbon fiber, glass fiber, and woven polyethylene tape reinforced composites. These columns are more flexible and aesthetically pleasing, and they have dentin-like properties. However, they should only be used if there is enough tooth tissue remaining, as they can delaminate when exposed to moisture, which can lead to later failure.

The carbon fiber post deforms very little and can absorb and transmit forces like dentin. However, these posts can be dark, which can lead to an unsightly result as the posts can glow through the teeth.

Fiberglass / Fiberglass

Fiberglass posts are more brittle than ceramic posts. Columns with unidirectional fibers are the strongest. However, this material is difficult to produce because the fiber bundles need to be impregnated and wetted with resin. This process often leaves voids on the fiber surface, resulting in a weakened structure.

Conventional metal columns are used due to their good corrosion resistance and high yield strength.

Prefabricated columns are available in stainless steel, titanium, titanium alloys and gold alloys. These types of piles are usually placed in the space of the pile and the core is constructed with direct repair core material.

There are also prefabricated columns, on which their cores are cast. These columns are typically made of type IV gold alloys (containing gold, platinum, palladium, and iridium) or platinum, gold, and iridium alloys and are compatible with palladium and silver free alloys or platinum, gold, palladium, and silver alloys.

Metal alloys, such as type IV gold alloys, are usually used.

13. What is the price of post and core?

A post and core usually cost between $350 and $650. It may vary depending on the material of the post and core you choose.

14. Other questions related to post and core:

1) What happens without posts and cores?

If a dentist attaches a crown to your severely decayed tooth, that tooth will further weaken and break. If the fracture is severe, or if the tooth becomes infected, you may lose the tooth.

Your dentist will need to replace it with dental implants and crowns – which are more expensive than dental posts and dental cores. A single implant surgery costs more than $1,500. In addition, there are additional costs associated with implants, including surgery, sedation, implant crowns, and more.

Your dentist is after advice and at the heart of protecting your oral health and limiting your long-term out-of-pocket costs. Listen to your dentist, not your dental insurance company.

2) How to choose a post?

While dentists usually have a bunch of sizes to choose from, it’s easy for them to know which one to try first from the variety.

The size of the post (diameter and taper) usually matches the size of the drill and file (the instruments used to create the post space).

3) After placing the post and core, how long does it take to complete the crown?

Depending on the materials chosen for the crown post and core formation, the dentist may begin the crowning process of the tooth at the same time.

When this is not possible, the dentist may rely on the completed post and core to act as a temporary (temporary) restoration of the tooth.

If so, ask your dentist what precautions to take (such as avoiding severe bite force and generally good for the teeth) and the acceptable time frame before you should start wearing a new crown.

4) How long will the post and core processes take?

If a prefabricated post is placed, and additional treatment of the tooth is performed at the same time as the crown is formed, the post and core can be built in about 15 minutes.

If the process is a separate process, your appointment may take around 30 minutes.

In cases where a cast/milled/indirect post and core is planned, the process typically takes two separate appointments, with a period of about a week or two in between. In order to fabricate your restoration, a dental laboratory will need a certain amount of time.

5）Does having a post and core placed hurt? Will you require an anesthetic?

Usually not. By definition, post & cores are only placed in end odontically treated teeth (teeth whose nerve tissue has been removed). So, there’s literally no nerve inside your tooth to register pain. Vibrations associated with the procedure (such as those from the dentist’s drill) may be felt, but pain should not be experienced.

However, your dentist might still numb you up anyway for some reasons.

• In most cases, the tooth has broken off at or below the gum line. As a result, your dentist may prod or poke at your gum tissue during their work, It may be necessary to numb you up before the procedure.
• Rubber dams may also be used to protect your dentist during this procedure. (So the interior of the tooth isn’t exposed to saliva and contaminants.To prevent you from swallowing items.)

6) How did you feel during the post and core placement process?

Whether or not your procedure used anesthesia, you’ll feel a slight vibration during the drilling process, or you’ll use hand tools as your dentist creates space for the post inside the tooth.

Likewise, when core parts are constructed, this may involve tooth trimming, pin placement, and restorative molding/contouring.