Utilization of Er:YAG Laser in Retrieving and Reusing of Lithium Disilicate and Zirconia Monolithic Crowns in Natural Teeth: An In Vitro Study

Round 1

Reviewer 1 Report

Comments to the authors.

General considerations.

The study is interesting and has been well-conducted from the methodological perspective. In particular. I’ve appreciated the attempt to reproduce conditions such as using a typodont mounted in a manikin head to simulate clinicians’ gesture and posture which can affect the irradiation process.

I’ve not major concerns and in my opinion the manuscript is suitable for publication in the journal. However, I would recommend:

1. A revision of the scientific english language since in some parts the text needs to be streamlined
2. In the introduction section, it would be interesting to report a brief paragraph explaining the physical properties and clinical effects and side-effects of Er:YAGand wavelenght in this range (2940 nm)

Author Response

Reviewer #1

The study is interesting and has been well-conducted from the methodological perspective. In particular. I’ve appreciated the attempt to reproduce conditions such as using a typodont mounted in a manikin head to simulate clinicians’ gesture and posture which can affect the irradiation process.

I’ve not major concerns and in my opinion the manuscript is suitable for publication in the journal. However, I would recommend:

A revision of the scientific English language since in some parts the text needs to be streamlined

RESPONSE: We appreciate the insight.

TEXT CHANGES: The manuscript is being re-read and edited accordingly.

In the introduction section, it would be interesting to report a brief paragraph explaining the physical properties and clinical effects and side-effects of Er:YAGand wavelenght in this range (2940 nm)

RESPONSE: We appreciate the input.

TEXT CHANGES: The following effects of Er:YAG laser at 2940 nm to the crowns and implant abutments from previous studies were summarized in the introduction.

“When applying Er:YAG laser at 2940 nanometer (nm) wavelength to remove lithium disilicate crowns from dental implant abutments, the removal time ranged from ~3-5 minutes (min),[23,24] and the temperature of the crowns appeared to increase by 4-6°C. [23,24]. When similar set up and laser was used to remove zirconia crowns from implant abutments, the average removal time increased to almost 6 min, while the temperature increased by 3-7°C.[25] The Er:YAG laser at 2940 nm wavelength does not seem to have any adverse effects toward lithium disilicate or zirconia crown or implant abutment materials.[23–25] However, repeated Er:YAG laser assisted crown retrieval seems to increase the amount of remaining cement in the implant crown[24,25], and increase the surface roughness through roughening of feldspathic glaze porcelain on the zirconia implant crown surface.[25]”

Reviewer 2 Report

The manuscript is nicely written, clear and very informative. All my compliments for this. 

Please find some suggestions below:

. Table 1, the legend should mention (sec) and not (min).

. Please consider that the laser parameters were effective when using the thickness of materials indicated in your study. You should mention in the Discussion section that thicker materials might need other parameters (we tested this and with thicker materials it does not work ... or it is so slow that clinically it is not feasible)

Author Response

Reviewer #2

The manuscript is nicely written, clear and very informative. All my compliments for this.

Please find some suggestions below:

. Table 1, the legend should mention (sec) and not (min).

RESPONSE: We appreciate the kind comment.

TEXT CHANGES: The legend of the Table 1 is now sec.

. Please consider that the laser parameters were effective when using the thickness of materials indicated in your study. You should mention in the Discussion section that thicker materials might need other parameters (we tested this and with thicker materials it does not work ... or it is so slow that clinically it is not feasible)

RESPONSE: We appreciate the kind comment. We agree that different thickness of materials may alter the effects of the laser.

TEXT CHANGES: We added the material thickness in our study’s limitations and future studies. The texts were amended as followed.

“Finally, only one cement and one crown thickness (of 1-1.5 mm) were used in this study, different variations of cements and cementation protocols may alter the retrieval results. Future studies should focus on in vivo experiments to evaluate the retrieval time, different cementation protocols, different material thicknesses as well as clinical challenges and possibly patient’s perceptions.”