Read the article to know about screw and cement-retained restorations and how they come with their own advantages and limitations.
The routine fixed dental implant prosthesis (FDP) is either a cement-retained crown (using a crown cemented over an abutment into the implant head) or a screw-retained crown (direct prosthetic retention screwed into the implant head). Over the past four decades, implant-supported fixed prostheses (ISFP) treatment has undergone tremendous growth and has become standard dental care. This success is attributed to the immense evolution of implant surfaces and designs, prosthetic components, clinical techniques, and dental materials.
Various clinical and laboratory procedures are involved in the fabrication of implant-supported reconstructions, including numerous decisions related to the use of implant components, materials, etc. During the treatment phase, the clinicians and the technician must decide the retention mode (i.e., screw or cement-retained) since both retention methods have their own advantages and limitations.
Advantages And Disadvantages of Cement-Retained Restorations:
Cement-retained restoration has benefits such as:
The main disadvantage is difficulty in removing excess cement, which is one of the primary causes for the development of peri-implant mucositis and peri-implantitis.
Advantages And Disadvantages of Screw-Retained Restorations:
Screw-retained fixed dental prostheses (FDP) has the following benefits:
The disadvantages are:
Both fixations influenced clinical outcomes in different ways. The screw-retained restoration was more easily retrievable than a cemented one. Therefore, these reconstructions are preferable technically and eventually for their biological compatibility.
PICO Strategy for Cement Vs. Screw Abutments:
The PICO (population, interventions, comparisons, and outcome) strategy was used by researchers to question and analyze the complications (including technical and biological ) of implant-supported full-arch dentures in patients treated with either screw-retained or cement-retained reconstructions.
The technical complications include:
The biological complications include:
Both types of fixations of the implant-supported prostheses influence the clinical outcomes in their own way. None of the fixation methods are clearly advantageous over the other. Overall, cement-retained prostheses exhibited more biological problems, implant failure, or marginal bone loss than screw-retained constructions.
A high success rate was found in screw-retained cases using all-4 concepts and preferred in full arch restorations. Screw-retained prostheses are easily retrievable; therefore, technical complications can be repaired more easily. This type of rehabilitation also seems preferable from a biological perspective.
All-On-4 Concept for Full-Arch Restorations:
The all-on-4 concept (Nobel Biocare) is an immediate loading protocol for full-arch rehabilitation of edentulous arches. Four implants (two posterior tilted implants and two anterior axial implants) are placed without any bone augmentation in cases of minimum bone volume. The surgical planning software with cone-beam CT(CBCT) and digital imaging and communications in medicine (DICOM) files from CT scans helps convert data into three-dimensional (3D) images to accurately perform virtual planning of the exact direction and position of the implants.
There are some contraindications to these techniques:
1) In case of a high smile line where bone reduction is necessary in the maxilla or in cases of a thin and irregular crest in the arches, which prevents proper treatment.
2) It provides enough implant and prosthetic space.
Failure of Implant Crown Prosthesis:
The cluster pattern of the implant loss may have been related to the smoking habits of the patients. Titanium frameworks have shown more problems with fracture of veneer compared with gold-alloy frameworks. It has been suggested that an inner-occlusal metal should be delivered on the palatal side for grinding and overloading. Also, increased functional load in the posterior quadrants is an essential factor, which results in implant failure.
Implant failure tends to cluster within-subjects, suggesting that heterogeneous risks may exist among the patient population. Patient-related factors may be a possibility, which would affect the survival of all implants within a given patient population and cause multiple implant failures.
Wearing CDs in the maxilla was associated with more significant implant failure in the mandible due to increased local closing and chewing forces bilaterally in the distal direction of mandibular implant-supported cross arch prostheses occluding with CDs. Masticatory forces are better distributed when the prostheses antagonize nature dentition or a fixed restoration instead of a removable denture. However, a combination of smoking, poor oral hygiene, and a history of periodontitis increases the risk of implant failure. Patients should be informed that smoking during the initial healing phase following implant insertion or a history of significant smoking increases the risk for implant failure.
In the case of cementation of fixed prostheses, proper removal of excess cement is crucial to prevent biological complications. More failure was found in both screw and cement-retained prostheses with metal-resin framework than metal-ceramic or fiber-reinforced acrylic resin bridges. There was a high risk for peri-implant bone loss in the IL-1 composite genotype-positive and smoking patients. Therefore, it is essential to consider the incidence of these kinds of complications during the development of a treatment plan.
Screw retained restorations are more advantageous biologically than the cement-retained prosthesis. Still, both can fail eventually if there is negligence of oral hygiene or has associated risk factors like smoking habit or local patient factors like heavy masticatory forces and increased functional loads. The dental implantologist or surgeon should consider the necessary elements before planning the treatment for a fixed dental prosthesis (FDP).
A small spatula is used to place cement into the inner side of the crown. Later the crown is seated to the abutment. The Teflon tape must be removed immediately from the hole, and the excess cement must be cleaned. It is left to cure for six minutes. Finally, a silicon high-shine rubber wheel is used to remove the excess cement at the margin after curing.
The major reasons for the failure of fixed prosthetic cementation are over tapered preparations, excessive amounts of cement, short clinical crowns, and leakage or open margin.
A cement-retained implant crown refers to the abutment upon which the implant crown is cemented. The advantage of a cement-retained implant crown is it compensates for improperly inclined implants. A passive fit is achieved because of the intervention layer of cement between the reconstruction and the implant abutment.
Cemented crowns can be retrieved if the correct amount of cement is used while cementing. Adding a water-soluble gel to the cement can ease the removal of the crown. But it is easier in the case of screw-retained implant crowns as the major advantage of a screw-retained crown is retrievability.
Screw-retained crowns are prosthetic components that connect directly to the endosseous dental implants, intended to aid the prosthetic rehabilitation of missing teeth.
Gutta-percha is used to block the darkness inside the crown. Then the porcelain is etched with 9% hydrofluoric acid for 3 to 4 minutes and later rinsed and dried thoroughly. Silanate the porcelain, followed by the application of unfilled resin. Then light-cured for20 seconds. Later application of pink opaque followed by application of opaque that matches the vita shade of the crown and light-cured for 20 seconds. Then composites are applied in increments and light-cured for 20 seconds every increment. Finally, tints are applied to the occlusal surface to create a natural look.
Screw-retained implant bridges are prosthetic components that replace the missing teeth by inserting two or more titanium roots into the jawbone and attaching crowns over them.
When excess cement is left over, it becomes a major problem. It can result in soft tissue damage, bone loss, and chronic inflammation.
Screw retained dentures are prostheses that serve as an aid to replace the missing teeth. The replacement teeth are mounted on a pink resin base formed over a metal structure to have the exact fit over the existing gums. They are placed by inserting titanium roots into the supporting bone.
With appropriate oral hygiene such as regular brushing and flossing, the implant screws can last a lifetime, whereas the crowns can last for about 10 to 15 years. Later it may need a replacement due to wear and tear. This duration is calculated assuming that the patient has regular dental check-ups every six months.
Even if dental implants have a high success rate, there are some disadvantages. The main disadvantage is that implants are a costly procedure, and they cannot be covered under insurance, pain, swelling, and infection. There can also be some anesthesia complications like persistent numbness, nausea, and drowsiness.
Both the snap-on dentures and dental implants bridges use titanium roots as a replacement for the missing teeth, but the significant difference is that dental implant-supported bridges are permanent, whereas snap-on dentures are not. Snap-on dentures can be removed or connected with your hands by giving some pressure. Snap-on dentures are attached to the implants, whereas fixed dental implant-supported bridges are sealed using dental cement.
Generally, snap-on dentures are not painful as the procedure is done under local anesthesia. The discomfort from this procedure is typically very low.
Last reviewed at:
15 Oct 2021 - 4 min read
Article Overview: Dental implants are the most reliable and well-established option for the replacement of missing teeth. Read the article to know the conditions and risk factors that can interfere with the integration of an implant into the jaw bone, along with the relevant management by the dental surgeon. Read Article
Introduction: According to the dental surgeon or implantologist, the key factor for a successful implant is the right or appropriate patient selection suitable for an implant prosthesis. Like all surgical procedures, a dental implant procedure can be performed only after verifying the patient's med... Read Article
Query: Hi doctor, What are the ramifications if you lose 20 pounds with new dental implants? I have lost seven pounds since this month. Also, having immediate dentures over implants, my dentist gave me a water pik and said it is fine to leave the immediate dentures in for a month while my extraction area ... Read Full »
Most Popular Articles
Do you have a question on Dental Implant Failure or Denture Implant?Ask a Doctor Online