The purpose of this study is to compare esthetic, functional and biological properties of two restoration materials used to fill cavities. One material is called "Filtek™ Supreme" which is a traditional tooth colored resin composite that is placed in the cavity in layers and hardened with UV light. The second material is called "SonicFill™ 2," which is a bulk fill composite that uses an ultrasonic hand piece to change the material from a solid into a liquid in order to place it into the cavity. This material can be placed in the cavity in 1 layer, and is hardened using UV light. Both materials have been FDA approved as non-significant risk devices for filling cavities.

In each subject, one tooth with a cavity will be randomly selected to receive one filling material, and a second tooth with a cavity will be randomly selected to receive the second material. The fillings will be observed over a two year period to determine clinical acceptability.

This study is a randomized, split-mouth, controlled, examiner-blinded clinical evaluation of Class II restorations using a new bulk-fill composite (SonicFill™ 2) and comparing it to Filtek™ Supreme resin composite placed in the traditional incremental technique.

The primary objective of this study is to evaluate the clinical performance of a sonic-activated, bulk fill composite, SonicFill™ 2, by comparing it to Filtek™ Supreme in the following categories:

Esthetic Properties

• Surface luster
• Staining - surface
• Staining - margin
• Color match and translucency
• Esthetic anatomical form

Functional Properties

• Fracture of material and retention
• Marginal adaptation
• Approximate anatomical form - contact point
• Radio-graphic examination (when applicable)
• Patient's view

Biological Properties

• Postoperative (hyper-)sensitivity and tooth vitality
• Recurrence of caries, erosion, abfraction
• Tooth integrity (enamel cracks, tooth fractures)
• Adjacent mucosa

The hypothesis to be tested is that the sonic-activated, bulk fill composite, SonicFill™ 2, will have comparable results to the traditional incremental technique composite, Filtek™ Supreme, in overall clinical acceptability and in all compared categories

Inclusion Criteria:

• Is at least 18 years of age
• Is willing to provide voluntary written informed consent
• Is in good medical health and able to tolerate the dental procedures
• Has at least 1 pair of qualifying molars or premolars that require Class II restorations.
• Restorations must have a buccal to lingual/palatal width equal to or greater than 1/3 the distance from buccal to lingual/palatal cusp tips
• Study teeth must be in occlusal function and must also be in contact with the neighboring tooth on at least one surface
• Study teeth must be vital (i.e., free of clinical signs and symptoms of periapical pathology)

Exclusion Criteria:

• Is currently taking part in an evaluation of other dental restorative materials
• Has chronic periodontitis or rampant caries
• Teeth exhibiting clinical signs of periapical pathology
• Teeth with a history of self-reported preoperative pulpal problems
• Women who are pregnant (self-reported). It is standard of care to post-pone routine dental procedures and radiographed until after pregnancy.
• Women who are breast feeding.
• Known allergy to resin composites or local anesthetics.
• Abnormal oral soft tissue findings (e.g., open sores, lesions)
• An employee of the sponsor or members of their immediate family.
• Condition affecting salivary flow (e.g., salivary gland disorder, Sjögren's Syndrome)
• Any restorative treatment of the teeth involved in the study in the last 12 months.
• Are unwilling or unable to have dental radiographs or photographs taken of their dentition and soft tissues
• Any other condition which is the view of the investigator may affect the ability of a patient to complete the study.

Each participants contributed 2 randomly selected teeth for each study group therefore 1 participant contributing 2 study teeth in each case. Therefore total number of participants is 45 and total number of units is 90.

Through study completion, an average of 24 months.

Other (Not Including Serious) Adverse Events: Adverse events that are not Serious Adverse Events.